SB2215E01
Oct.2001
Service Manual
G424 Gasoline/LP Engine
G424 LP Engine (Low Emission Version)
G20E-3, G25E-3, G30E-3
GC20E-3, GC25E-3, GC30E-3
Important Safety Information
Most accidents involving product operation, maintenance and repair are caused by failure to observe basic safety
rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an
accident occurs. A person must be alert to potential hazards. This person should also have the necessary
training, skills and tools to perform these functions properly.
Read and understand all safety precautions and warnings before operating or performing lubrication,
maintenance and repair on this product.
Basic safety precautions are listed in the “Safety” section of the Service or Technical Manual. Additional safety
precautions are listed in the “Safety” section of the owner/operation/maintenance publication.
Specific safety warnings for all these publications are provided in the description of operations where hazards
exist. WARNING labels have also been put on the product to provide instructions and to identify specific hazards.
If these hazard warnings are not heeded, bodily injury or death could occur to you or other persons. Warnings in
this publication and on the product labels are identified by the following symbol.
WARNING
Improper operation, lubrication, maintenance or repair of this product can be dangerous and could result
in injury or death.
Do not operate or perform any lubrication, maintenance or repair on this product, until you have read and
understood the operation, lubrication, maintenance and repair information.
Operations that may cause product damage are identified by NOTICE labels on the product and in this
publication.
DAEWOO cannot anticipate every possible circumstance that might involve a potential hazard. The warnings in
this publication and on the product are therefore not all inclusive. If a tool, procedure, work method or operating
technique not specifically recommended by DAEWOO is used, you must satisfy yourself that it is safe for you and
others. You should also ensure that the product will not be damaged or made unsafe by the operation, lubrication,
maintenance or repair procedures you choose.
The information, specifications, and illustrations in this publication are on the basis of information available at the
time it was written. The specifications, torques, pressures, measurements, adjustments, illustrations, and other
items can change at any time. These changes can affect the service given to the product. Obtain the complete
and most current information before starting any job. DAEWOO dealers have the most current information
available.
1
Index
GENERAL INFORMATION .......................................4
How to Read This Manual ....................................4
Precaution Before Service ....................................6
General .................................................................8
Tightening Torque .................................................9
Sealant ................................................................12
Alternator ............................................................47
IGNITION SYSTEM .................................................50
Breakerless Ignition System ...............................50
Distributor............................................................51
Removal and Installation ....................................54
Distributor, disassembly and reassembly ...........56
SPECIFICATIONS ...................................................13
General Specification ..........................................13
Service Specification ..........................................14
GASOLINE FUEL SYSTEM ....................................58
General Description ............................................58
Geasoline Carburetor, Operation........................59
Removal and Installation ....................................64
Gasoline Carburetor
Disassembly and Reassembly............................66
MAINTENANCE ......................................................17
Test Fuel System for Leaks ................................17
Check Engine Oil Level ......................................17
Inspect Engine for Fluid Leaks ...........................17
Change Engine Oil and Filter .............................17
Inspect Accessory Drive Belts ............................18
Inspect Electrical System....................................18
Inspect Vacuum lines and fitting .........................18
Check Coolant Level...........................................18
Inspect Coolant Hoses........................................18
Inspect Ignition System.......................................18
Replace Spark Plug ............................................18
Replace LP fuel filter element.............................19
Test Fuelock (electric) .........................................19
Replace Gasoline Fuel filter ...............................20
Inspect Gasoline Carburetor ...............................20
Inspect Pressure Regulator/Vaporizer ................20
Inspect LP Mixer (Standard LP Truck)................20
Inspect Variable Venturi Air/Fuel Mxer
(Low Emission LP Truck) ....................................20
Inspect Complete Exhaust System for
Leaks,damage ....................................................20
Engine Control Unit (ECU) and others
(Low Emission LP Truck) ....................................20
Maintenance Schedule .......................................21
LPG FUEL SYSTEM ...............................................73
General Description ............................................73
Electric Fuelock Model ..................................73
Converter .......................................................74
Fuel Tank .......................................................75
LP Relief Valve ..............................................75
Carburetor .....................................................76
Tests or Adjustments...........................................77
Carburetor Adjustment ..................................77
Fuel System Leak Check ..............................79
Recommendation for LP Fuel System ..........80
LP Converter - Check, Clean ........................81
Disassembly and Assembly ................................82
LPG Carburetor .............................................82
LP Gas Fuelock.............................................84
LP Gas Converter..........................................85
LPG FUEL SYSTEM (LOW EMISSION VERSION)..87
General Description ............................................87
LP Carburetor ................................................89
Vacuum switch (MAP) ...................................90
Vacuum switch ..............................................90
LP Converter .................................................91
Fuel Control Valve .........................................92
Fuelock Valve ................................................92
Engine Control Unit (ECU) ............................93
Oxygen Sensor..............................................94
Catalytic Muffler.............................................95
Tests or Adjustments...........................................96
LP Carburetor - Check, Clean.......................97
LP Converter-Check,Clean ...........................97
Inspection of Fuelock Valve ..........................97
Inspection of Fuel Control Valve ...................97
Inspection of Vacuum switch.........................97
Inspection of Vacuum switch (MAP)..............97
Inspection of Oxygen sensor.........................98
Disassembly and Assembly ................................99
LPG Carburetor .............................................99
LP Gas Converter........................................101
ENGINE SYSTEM ...................................................22
Engine Overview .................................................22
Timing System ....................................................25
Silent Shaft Mechanism ......................................26
Auto Lash Adjuster..............................................27
Intake and Exhaust System ................................28
Electrical System ................................................30
STARTING SYSTEM ...............................................32
General Description ............................................32
Start Relay Test ..................................................35
Start Motor ..........................................................36
Operation .......................................................36
Removal and Installation ...............................39
Disassembly and Reassembly ......................42
CHARGING SYSTEM..............................................47
General Description ............................................47
G424 Service Manual
2
Index
DUAL FUEL SYSTEM ...........................................102
General ..................................................187
Engine ....................................................189
Carburetor ..............................................190
Electrical Components ...........................192
GOVERNING SYSTEM .........................................103
General Description ..........................................103
Governor,Disassembly and Reassembly ..........104
SPECIAL TOOLS ..................................................195
LUBRICATION SYSTEM .......................................106
General Description ..........................................106
Testing and Adjusting ........................................107
Engine Oil...............................................107
Lubrication System Problem ..................107
Oil Pressure Check ................................109
COOLING SYSTEM ...............................................110
General Description ..........................................110
Testing and Adjusting ........................................111
Cooling System Visual Inspection ...............111
Cooling System Tests ..................................111
Thermostat...................................................113
Cooling system Heat Problem .....................114
Cooling System Recommendation ..............114
Belt Adjustment............................................116
V-belt Diagnosis...........................................116
Serivce Procedure ............................................117
Draining and Filling Cooling System ...........117
Flushing the Cooling System.......................118
Radiator Service ..........................................118
Removal & Install Water Temperature Sender ..119
BASE ENGINE SERVICE PROCEDURE .............120
Timing Belt ........................................................120
Intake Manifold .................................................129
Exhaust Manifold and Water Pump ..................130
Rocker Arms and Camshaft ..............................133
Cylinder Head and Valves ................................139
Front Case and Oil Pan ....................................145
Piston and Connecting Rod ..............................154
Crankshaft and Cylinder Block .........................162
ADJUSTMENT AND TROUBLESHOOTING ........169
Adjustment ........................................................169
Valve Clearnce Adjustment .........................169
Ignition Timing Adjustment ..........................169
Idle Speed Adjustment ................................171
Air Governor Adjustment .............................171
Anti-Hunting Adjustment ..............................171
Troubleshooting ................................................172
Engine Performance....................................172
Engine Starting Problems ...........................172
Charging System Problems ........................173
Instrument Problems ...................................173
Engine Noise ...............................................174
Oil Pressure Diagnostics .............................176
Oil Pressure Problems ................................177
Water in Engine ...........................................178
Engine Overheting.......................................179
LP Fuel System
(Standard and/or Low Emission Version)....180
Troubleshooting Flow Chart ........................187
G424 Service Manual
3
Index
GENERAL INFORMATION
How To Read This Manual
Scope of Explanation
This book describes the service procedures for the engine removed from the vehicle.
For procedures concerning removal of the engine from the vehicle and on-vehicle inspection and servicing, refer
to the appropriate service manuals separately prepared for the individual models.
Maintenance and Servicing Procedures
(1) A diagram of the component parts is provided
near the front each section in order to give the
reader a better understanding of the installed
condition of component parts.
(2) The numbers provided within the diagram
indicate the sequence for maintenance and
servicing procedures; the symbol N indicates a
non-reusable part; the tightening torque is
provided where applicable.
• Removal steps:
The part designation number corresponds to the
number in the illustration to indicate removal steps.
• Installation steps:
Specified in case installation impossible in reverse
order of removal steps. Omitted if installation is
possible in reverse order of removal steps.
• Disassembly steps:
The part designation number corresponds to the number
in the illustration to indicates disassembly steps.
• Reassembly steps.
Specified in case reassembly is impossible in
reverse order of disassembly steps. Omitted if
reassembly is possible in reverse order of
disassembly steps.
Classification of Major Maintenance/Service points
When there are major points relative to maintenance and servicing procedures (such as essential
maintenance and service points, maintenance and service standard values, information regarding the
use of special tools, etc.), these are arranged together as major maintenance and service points and
explained in detail.
A
: Indicates that there are essential points for removal or disassembly.
B
: Indicates that there are essential points for installation or reassembly.
Symbols for Lubrication, Sealants and
Adhesives
Information concerning the locations for
lubrication and for application of sealants and
adhesives if provided, by using symbols, in the
diagram of component parts, or on the page
following the component parts page, and
explained.
.... Sealant or adhesive
.... Engine oil or gear oil
Inspection
Only the inspections to be performed by using special tools or measuring instruments are covered. General
service procedures not covered in this manual, such as visual inspections and cleaning of parts, however, should
always be performed during actual service operations.
G424 Service Manual
4
General Information
FRONT CASE AND OIL PAN
REMOVAL AND INSTALLATION
6EN1898
Removal steps
N
M
A
L
K
B
J
C
I
H
1. Oil filter
2. Oil pressure switch
3. Drain plug
4. Drain plug gasket
5. Oil pan
6. Oil screen
7. Oil screen gasket
8. Plug
9. O-ring
10. Flang bolt
11. Relief plug
12. Gasket
13. Relief spring
14. Relief plunger
15. Oil filter bracket
16. Oil filter bracket gasket
MD998727
G
G
G
F
E
D
D
E
E
C
B
A
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
Oil pump case assembly
Front case gasket
Oil pump cover
Oil pump drive gear
Oil pump driven gear
Crankshaft front oil seal
Oil pump oil seal
Counterbalance shaft oil seal
Front case
Counterbalance shaft, left
Counterbalance shaft, right
Counterbalance shaft, front bearing
Counterbalance shaft, rear bearing, left
Counterbalance shaft, rear bearing, right
REMOVAL SERVICE POINTS
A
Oil pan removal
(1) Remove the all oil pan bolts.
(2) Drive in the special tool between the cylinder block and oil pan.
(3) Side the tool by striking the edge of the special tool to separate the oil
pan from the cylinder block.
6EN0698
This alphabetical letter corresponds to the one assigned
to a part in the removal, installation, disassembly or
reassembly steps that are indicated in the drawing on the
first page of each section.
G424 Service Manual
Operating procedures, cautions, etc.
on removal, installation, disassembly
and reassembly are described
5
General Information
Precautions Before Servce
Removal and Disassembly
For prevention of wrong installation or reassembly and for
ease of operation, put mating marks to the parts where no
function is adversely affected.
1EN0018
Special Tool
Be sure to use Special Tools when their use is specified for
the operation.
Use of substitute tools will result in malfunction of the part
or damage it.
1EN0019
Tightening Torque
Tighten the part properly to specified torque.
1EN0020
SE
AL
AN
T
Sealant
Use specified brand of sealant.
Use of sealant other than specified sealant may cause
water or oil leaks.
1EN0021
G424 Service Manual
6
General Information
Replacement Part
When oil seal, O-ring, packing and gasket have been
removed, be sure to replace them with new parts.
However, rocker cover gasket may be reused if it is not
damaged.
1EN0022
Rubber Parts
Do not stain timing belt and V-belt with oil or water.
Therefore, do not clean the pulley and sprocket with
detergent.
1EN0023
Oil and Grease
Before reassembly, apply specified oil to the rotating and
sliding parts.
1EN0024
Genuine Part
When the part is to be replaced, be sure to use genuine
part.
For selection of appropriate parts, refer to the Parts
Catalog.
1EN0025
G424 Service Manual
7
General Information
General
Engine models and numbers
Engine model
Fuel type
G424
Gasoline, LPG, LPG (Low Emission Version)
Indication of engine model and number
The engine model and serial number are stamped on the right side of cylinder block surface.
Engine model
Engine number
4G64
AA0001 to YY9999
6EN1916
G424 Service Manual
8
General Information
Tightening Torque
Major Bolts and Nuts
Torque
Item
Remarks
kg•m
lb•ft
N•m
Water pump pulley bolt
0.9
6.5
9
Crankshaft pulley bolt
2.5
18.1
25
Spark plug
2.5
18.1
25
Distributor nut
1.2
8.7
12
Timing belt cover bolt
1.1
8.0
11
0.9
6.5
9
Tensioner spring spacer
4.9
35.4
48
Tensioner bolt
4.9
35.4
48
Oil pump sprocket nut
5.5
39.8
54
Crankshaft bolt
12.0
86.8
118
Tensioner B bolt
1.9
13.7
19
Counterbalance shaft
4.6
33.3
45
Engine support bracket bolt
3.6
26.0
35
Camshaft sprocket bolt
9.0
65.1
88
Timing belt rear bolt
1.4
10.1
14
Fuel system
Carburetor nut
1.2
8.7
12
carburetor
Air horn nut
1.2
8.7
12
Stud
1.2
8.7
12
Fuel pump
1.1
8.0
11
LPG carburetor nut
1.2
8.7
12
LPG carburetor Fuel pump cover
1.1
8.0
11
Intake manifold Water outlet bolt
1.4
10.1
14
Intake manifold bolt/nut
1.8
13.0
18
Exhaust
Oil level gauge guide bolt
1.4
10.1
14
manifold
Heat protector bolt
0.9
6.5
9
Exhaust manifold nut
3.5
25.3
34
Water inlet pipe bolt
1.4
10.1
14
Water pump bolt
1.4
10.1
14
Rocker cover bolt
0.6
4.3
6
M8 B 25
2.4
17.4
24
M6 B 65
2.0
14.5
20
Ignition system
Tensioner belt
Fuel system
Rocker arm
and camshaft
Bearing cap bolt
Cylinder head,
valve
Cylinder head bolt
G424 Service Manual
8.0 kgf•m(57.9 lb•ft)[78 N•m]+ 0 +
2.0 kgf•m(14.5 lb•ft)[20 N•m]+
1/4 turn + 1/4 turn
9
General Information
Torque
Item
Remarks
kg•m
lb•ft
N•m
Drain plug
4.0
28.9
39
Oil pan bolt
0.7
5.1
7
Oil screen bolt/nut
1.9
13.7
19
Oil pressure switch
1.0
7.2
10
Front case,
Plug
2.4
17.4
24
doil pan
Flange bolt
3.7
26.8
36
Relief plug
45
32.5
44
Oil filter bracket
1.9
13.7
19
Oil pump cover bolt
1.7
12.3
17
Oil pump cover screw
1.0
7.2
10
Front case bolt
2.4
17.4
24
Piston,
Connecting rod bearing nut
connecting rod.
Flywheel bolt
Crankshaft,
cylinder block
13.5
97.6
132
0.9
6.5
9
6.0
43.4
59
Rear plate cover
1.1
8.0
11
Oil seal case bolt
1.1
8.0
11
Rear plate bolt
Bearing cap bolt
Starter motor
2.0 kg•m(14.5 lb•ft) [20 N•m]+ 1/4 turn
Starter motor bolt
G424 Service Manual
2.0 kg•m(14.5 lb•ft) [20 N•m]+ 1/4 turn
2.7
19.5
10
26
General Information
General Bolts and Nuts Tightening Torque
Standard Bolts and Nuts
Torque, kg•m (lb•ft) [N•m]
Nominal
diameter
Pitch
Bolt, stud, nut (with spring washer)
Flange bolt, flange nut
Head mark 4
Head mark 7
Head mark 10
Head mark 4
Head mark 7
M5
M5
-
0.5 (0.5) [3.6]
-
-
0.6 (4.3) [5.9]
M6
M6
-
0.9 (6.5) [8.8]
1.2 (8.7) [12]
-
1.0 (7.2) [9.8]
M7
M7
1.2 (8.7) [12]
2.2 (15.9) [22]
3.0 (21.7) [29]
1.3 (9.4) [13]
2.4 (17.4) [24]
M8
M8
2.5 (18.1) [25]
4.5 (32.5) [44]
6.0 (43.4) [59]
2.6 (18.8) [25]
5.0 (36.2) [49]
M9
M9
4.2 (30.4) [41]
8.6 (60.0) [81]
10.7 (77.4) [105]
4.7 (34.0) [46]
9.5 (68.7) [93]
M10
M10
7.3 (52.8) [72]
14.0 (101.3) [137]
14.5 (104.9) [142]
-
-
Tapered Threads
Torque, kg•m (lb•ft) [N•m]
Size
Material of internal threads:
Material of internal threads:
Aluminum alloy
Cast iron or steel
NPTF 1/16
0.5 to 0.8 (3.6 to 5.8) [5 to 8]
0.8 to 1.2 (5.8 to 8.7) [8 to 11]
PT 1/8
0.8 to 1.2 (5.8 to 8.7) [8 to 11]
1.5 to 2.2 (10.8 to 15.9) [15 to 21]
PT 1/4
2.0 to 3.0 (14.5 to 21.7) [20 to 29]
3.5 to 4.5 (25.3 to 32.5) [34 to 44]
NPTF 1/4
2.0 to 3.0 (14.5 to 21.7) [20 to 29]
3.5 to 4.5 (25.3 to 32.5) [34 to 44]
PT 3/8
4.0 to 5.5 (28.9 to 39.8) [39 to 59]
5.5 to 7.5 (39.8 to 54.2) [54 to 73]
PT 1/2
7.0 to 10.0 (50.6 to 72.3) [69 to 98]
12.0 to 16.0 (86.8 to 115.7) [118 to 156]
New Tightening Method-By Use of Bolts to be Tightened in Plastic Area
A new type of bolts, to be tightened in plastic area, is currently used in some parts of the engine. The tightening
method for the bolts is different from the conventional one. Be sure to observe the method described in the text
when tightening the bolts.
Service limits are provided for the bolts. Make sure that the service limits described in the text are strictly
observed.
where the bolts are in use:
•Area
(1) Cylinder head bolts
(2) Main bearing cap bolts
(3) Connecting rod cap bolts
method
•Tightening
After tightening the bolts to the specified torque, tighten them another 90° or 180° (twice 90°). The tightening
method varies on different areas. Observe the tightening method described in the text.
G424 Service Manual
11
General Information
Sealant
Part to be Applied
Brand
TM
Semi circular packing
3M
AAD Part No.8672 or equivalent
Rocker cover
3MTM AAD Part No.8672 or equivalent
Oil pressure switch
3MTM AAD Part No.8672 or equivalent
Oil pan
Silicone RTV sealant or eguivalent
Rear oil seal case
Silicone RTV sealant or eguivalent
Rear plate bolt
3MTM AAD Part No.8672 or equivalent
Oil seal case bolt
3MTM AAD Part No.8672 or equivalent
From in Place Gasket (FIPG)
The engine has several areas where the from-in-place gasket(FIPG) is in use. To ensure that gasket fully serves
its purpose, it is necessary to observe some precautions when applying the gasket. Bead size, continuity and
location are of paramount importance. Too thin a bead could cause leaks. Too thick a bead, on the other hand,
could be squeezed out of location, causing blocking or narrowing of the fluid feed line. To eliminate the possibility
of leaks from a joint, therefore, it is absolutely necessary to apply the gasket evenly without a break, while
observing the correct bead size.
Since the FIPG used in the engine hardens as it reacts with the moisture in the atmospheric air, it is normally
used in the metallic flange areas.
Disassembly
The parts assembled with the FIPG can be easily disassembled without use of a special method. In some cases,
however, the sealant between the joined surfaces may have broken by lightly striking with a mallet or similar tool.
A flat and thin gasket scraper may be lightly hammered in between the joined surfaces. In this case, however,
care must be taken to prevent damage to the joined surfaces. For removal of the oil pan, the special tool “Oil Pan
Remover” (MD998727) is available. Be sure to use the special tool to remove the oil pan.
Surface preparation
Thoroughly remove all substances deposited on the gasket application surfaces, using a gasket scraper or wire
brush.
Check to ensure that the surfaces to which the FIPG is to be applied is flat. Make sure that there are no oils,
greases and foreign substances deposited on the application surfaces. Do not forget to remove the old FIPG
remaining in the bolt holes.
From-in-place gasket Application
Applied FIPG bead should be of the specified size and without breaks. Also be sure to encircle the bolt hole
circumference with a completely continuous bead. The FIPG can be wiped away unless it is hardened. While the
FIPG is still moist (in less than 15 minutes), mount the parts in position. When the parts are mounted, make sure
that the gasket is applied to the required area only.
The FIPG application procedure may vary on different areas. Observe the procedure described in the text when
applying the FIPG.
G424 Service Manual
12
General Information
SPECIFICATIONS
General Specifications
Engine model
Item
G424
Type
Water-cooled, 4-cycle, gasoline-powered and L.P.G.-powered
No. of cylinders and arrangement
4, in-line
Combustion chamber type
Semi-spherical
Valve mechanism
OHC
3
Total displacement, cm (cc) [cu in.]
2350 (2350) [143]
Bore x stroke, mm (in.)
86.5 B 100 (3.41 B 3.94)
Dry weight, kg (lb)
146 (322)
Compression ratio
8.6
2
Compression pressure, kPa (kgf/cm ) [psi]
Valve timing
1128 (11.5) [163.5]
Intake
Open
12° BTDC
valve
Close
40° ABDC
Exhaust
Open
54° BBDC
valve
Close
6° ATDC
Firing order
1-3-4-2
Ignition timing, BTDC/rpm
4°/740 (gasoline), 9°/740 (L.P.G.), 4˚/740(dual fuel)
Fuel pump
Gasoline
Mechanical (diaphragm type)
Carburetor
Down-draft type
Governor
Air flow type
Lubrication system
Pressure feed, full-flow filtration type
Oil pump
Gear, driven by timing belt
Oil filter
Filter paper, cartridge type
Cooling system
Water-cooled, forced circulation
Water pump
Centrifugal, driven by V-belt
Thermostat
Wax type
Electrical system
12V DC, negative ground
Alternator, (12V-61A)
Alternator current, built-in fan and regulator
Starter motor, (12V-1.2kW)
Reduction drive
Distributor
Equipped with automatic timing controller, breaker less type
Spark plug (NGK)
Gasoline
BPR4ES
L. P. G.
BPR5ES
3
Quantity of lubricating oil, cm (liter) [U.S.gal]
4000(4.0) [1.06 ]( including 300 cm3(0.3 liter)[0.08 U.S.gal ]in oil filter
Quantity of coolant, cm3 (liter) [U.S.gal]
IDLE RPM
G424 Service Manual
LOW (RPM)
3100 (3.1) [0.82] (in engine proper)
700 L 25
HIGH (RPM)
2700 L 50
13
Specifications
Service Specifications
Unit : mm(in.)
Standard value
Item
Flatness of gasket surface
Total resurfacing
depth of both
0.2 (0.008)
cylinder head and
cylinder block
Cylinder head
Camshaft
Overall height
89.9 to 90.1 (3.539 to 3.547)
Oversize rework
dimensions of valve
guide hole
0.05 (0.0020)
13.05 to 13.07 (0.5138 to 0.5146)
0.25 (0.0098)
13.25 to 13.27 (0.5217 to 0.5224)
0.50 (0.0197)
13.50 to 13.57 (0.5315 to 0.5343)
Intake
Oversize
rework
dimensions of
Exhaust
valve seat
ring hole
0.30 (0.0118)
47.30 to 47.33 (1.8622 to 1.8634)
0.60 (0.0236)
47.60 to 47.63 (1.8740 to 1.8752)
0.30 (0.0118)
40.30 to 40.33 (1.5866 to 1.5878)
0.60 (0.0236)
40.60 to 40.63 (1.5984 to 1.5996)
Intake
41.62 (1.6386)
41.12 (1.6189)
Exhaust
41.62 (1.6386)
41.12 (1.6189)
Journal diameter
33.935 to 33.950 (1.33602 to 1.33661)
Oil clearance
Overall length
0.05 to 0.09 (0.0020 to 0.0035)
Intake
106.6 (4.197)
106.1 (4.126)
Exhaust
105.2 (4.142)
104.7 (4.122)
42.05 (1.6555)
42.55 (1.6752)
Valve stem projection
Piston Valve seat Valve guide Valve spring
Valve
Stem diameter
Intake
7.960 to 7.975 (0.31339 to 0.31398)
Exhaust
7.930 to 7.950 (0.31220 to 0.31299)
Face angle
45° to 45.5°
Thickness of valve
Intake
head (margin)
Exhaust
Stem-to-guide
Intake
0.025 to 0.058 (0.00098 to 0.00228)
clearance
Exhaust
0.050 to 0.088 (0.00197 to 0.00346)
1.2 (0.047)
2.0 (0.079)
Free height
48.0 (1.89)
Load/installed height
Inner diameter
Valve contact width
2° or less
Intake
47 (1.85)
Exhaust
52 (2.05)
4°
8.000 to 8.018 (0.31496 to 0.31567)
0.9 to 1.3 (0.035 to 0.051)
Sinkage
0.2 (0.008)
Outside diameter
86.47 to 86.50 (3.4043 to 3.4055)
Piston clearance
0.02 to 0.04 (0.0008 to 0.0016)
G424 Service Manual
47.0 (1.85)
176.5N (18kg) [39.7lbf]/40.4 (1.591)
Out-of-squareness
Overall length
Remarks
0.03 (0.0012)
Grinding limit
Cam height
Limit
14
Specifications
Unit : mm(in.)
Item
Standard value
Limit
No. 1 ring
0.25 to 0.40 (0.0098 to 0.0157)
0.8 (0.031)
No. 2 ring
0.45 to 0.60 (0.0177 to 0.0236)
0.8 (0.031)
Oil ring
0.20 to 0.60 (0.0079 to 0.0236)
1.0 (0.039)
Ring-to-ring groove
No. 1
0.03 to 0.07 (0.0012 to 0.0028)
clearance
No. 2
Crankshaft
Connecting rod
Piston pin
Piston ring
End gap
Outside diameter
Press-in load
7350 to 17160
(at room temperature),
(750 to 1750)
N (kg) [lbf]
[1650 to 3860]
Big end center-to small end center
Bend
0.05 (0.0020)
Twist
0.10 (0.0039)
Big end thrust clearance
0.10 to 0.25 (0.0039 to 0.0098)
End play
0.05 to 0.18 (0.0020 to 0.0071)
Journal outside diameter
56.982 to 57.000 (2.24338 to 2.24409)
Pin Outside diameter
44.985 to 45.000 (1.77106 to 1.77165)
Out-of-roundness and taper of
journal and pin
Concentricity journal and pin
Cylinder block
0.005 (0.00020)
0.03 (0.0012)
0.02 to 0.04 (0.0008 to 0.0016)
0.02 to 0.05 (0.0008 to 0.0020)
Cylinder inner diameter
86.50 to 86.53 (3.4055 to 3.4067)
Flatness of gasket surface
0.05 (0.0020)
Total resurfacing
depth of both
0.2 (0.008)
cylinder head and
cylinder block
Grinding limit
Overall height
Oil pump
149.9 to 150.0 (5.902 to 5.906)
length
Oil clearance of pin
Drive
belt
0.03 to 0.07 (0.0012 to 0.0028)
22.002 to 22.005 (0.86622 to 0.86634)
Oil clearance of journal
Side clearance
Deflection
289.9 to 290.1 (11.413 to 11.421)
Drive gear
0.08 to 0.14 (0.031 to 0.0055)
Drive gear
0.06 to 0.12 (0.0024 to 0.0047)
New belt
7.0 to 10.0 (0.28 to 0.39)
Used belt
10 (0.39)
Throttle bore diameter
Carburetor
Remarks
32 (1.26)
Outer venturi diameter
24 (0.94)
Inner venturi diameter
9 to 12 (0.35 to 0.47)
Main jet (Symbol Size)
132.5
Main air jet diameter
Pilot jet diameter
0.9 (0.035)
0.55 (0.0217)
Pilot air jet diameter
1.6 (0.063)
Primary throtle valve to throtle
bore clearance
1.1(0.043)
G424 Service Manual
15
Specifications
Unit : mm(in.)
Item
Standard value
Starter motor
Nominal output, kW
No-load characterstics
11.0
Current, A
90 or less
3000
Outer diameter
Runout
29.4 (1.16)
28.8 (1.13)
0.05 (0.0020)
0.1 (0.0039)
0.5 (0.020)
0.2 (0.008)
Undercut
Pinion gap
0.5 to 2.0 (0.020 to 0.079)
Tahermostat Spark plug Ignitio n coil Distributor
Brush length
Wear limit line
Centrifugal advance crank
Start
0°/1000
angle/engine speed, °/rpm
End
20°/5000
Vacuum advance crank
End
0°/80
angle/vacuum, °/mmHg
Start
23°/280
Primary coil resistance, Ω
1.08 to 1.32
Secondary coil resistance, Ω
22.1 to 29.9
0.7 to 0.8 (0.028 to 0.031)
Plug gap
Valve opening temperature, °C (˚F)
82 (180)
Fully opening temperature, ˚C (˚F)
95 (203)
Valve lift
Oil Pressure
G424 Service Manual
Remarks
1.2
Voltage, V
Speed, rpm
Commutator
Limit
8 (0.31) or more
Low Idle
50 kPa(7psi)
High Idle
450 kPa(65psi)
16
Specifications
1. Stop engine if in use.
MAINTENANCE
G424
engine
requires
a
certain
amount
2. Allow sufficient time (approximately 2 minutes) for
the oil to drain back into the oil pan.
of
maintenance. Suggested maintenance requirements
3. Remove dipstick. Wipe clean and reinstall. Push
dipstick all the way into the dipstick tube.
are contained in this section. The owner should,
however, develop his own maintenance schedule
4. Remove dipstick and note the oil level.
using the requirements listed in this section and any
5. Oil level must be between the "MAX" and "MIN"
marks.
other necessary requirements resulting from optional
additions to the engine system.
6. If the oil level is below the "MIN" mark, proceed to
Steps 7 and 8, and reinstall dipstick into the dipstick
tube.
Test Fuel System for Leaks
7. Remove oil filler cap from the valve rocker arm
cover.
• Obtain a pump spray bottle.
• Fill with an approved leak test solution or a mixture
of water and dish soap.
8. Add required amount of oil to bring level up to, but
not over, the "MAX" mark on dipstick.
• Spray a generous amount of the solution on the
entire fuel system including the fuel storage
container and fuel lines.
• Wait approximately 15-60 seconds then perform a
visual inspection of entire fuel system.
• Leaks will cause the soapy solution to bubble.
• Repair any leaks before continuing.
• Crank the engine through several revolutions. This
will energize the fuel lock and allow fuel to flow to the
pressure regulator/vaporizer. Apply additional leak
test solution to this portion of the fuel system and
inspect as above.
NOTE: When refill engine oil, refill same oil as that
used before.
• Repair any fuel leaks before continuing.
Inspect Engine for Fluid Leaks
• Start engine and bring up to operating temperature.
• Turn engine off.
• Inspect entire engine for oil and/or coolant leaks.
• Repair any/all leaks before continuing.
Change Engine Oil &Filter
• Start engine.
• Bring up to operating temperature.
• Shut down engine.
• Remove oil fill cap located in valve cover.
• Place drain pan under engine oil pan.
Check Engine Oil Level
• Remove oil drain plug located at bottom of oil pan
and allow engine oil to drain.
IMPORTANT : Care must be taken when checking
CAUTION : OIL WILL BE HOT.
engine oil level. Oil level must be main-tained between
• Remove engine oil filter. Make sure the oil filter
gasket does not stick to engine.
the "MIN" mark and the "MAX" mark on the dipstick. To
ensure that you are not getting a false reading, make
CAUTION : OIL WILL BE HOT.
sure the following steps are taken before checking the
• Using a clean shop towel clean the engine oil filter
gasket mating surface.
oil level.
• Fill oil filter with engine oil.
G424 Service Manual
17
Maintenance
• Lube oil filter gasket with engine oil.
• On open systems carefully remove cooling system
pressure cap. Coolant level will be approximately 3040 mm below pressure cap sealing surface. If level is
low replace pressure cap and repair any/all other
leaks.
• Install oil filter as per filter manufacturers
instructions. DO NOT OVER TIGHTEN
• Fill crankcase with engine oil.
• Start engine & run approximately 60 seconds.
• Shut down engine, wait approximately 2 - 5 minutes
and then check oil level.
Inspect Coolant Hoses
• When oil level is satisfactory start engine and check
for any possible leaks.
• Visually inspect coolant hoses and clamps.
• Replace any hose that shows signs of swelling,
cracking, abrasion hardening or any other
damage/deterioration.
• Repair any/all leaks before returning unit to service.
• Top-up cooling system with approved coolant.
NOTE
Engine Oil Specification : See, Lubrication System
section
Inspect Ignition System
• Remove and inspect spark plugs. Replace as
required.
Inspect Accessory Drive Belts
• Test secondary wires with an Ohmmeter. Maximum
resistance repair replace as required.
See, "Testing & Adjusting" of Cooling System Section.
• Remove distributor cap and perform visual inspection
of distributor cap and rotor. Replace cap & rotor if
corrosion is found on contacts.
Inspect electrical system
• Inspect distributor breaker unit and housing for signs
of corrosion. Repair replace as required.
• Clean battery outer surfaces with a mixture of baking
soda and water.
• Inspect battery outer surfaces for damage. Replace
as required.
Replace Spark Plugs
• Remove battery cables and clean.
• Utilizing a gentle twisting motion remove the
secondary high voltage leads from the spark plugs.
Replace any damaged leads.
• Inspect battery cables for worn or missing insulation,
frayed wire and/or corrosion. Replace as required.
• Remove the spark plugs.
Inspect Vacuum Lines and Fittings
• Gap new spark plugs to proper specs.
• Apply anti-seize compound to spark plug threads.
• Visually inspect vacuum lines and fittings for physical
damage such as brittleness, cracks, kinks and
misrouting. Repair/replace as required.
• Install spark plugs.
• Do not over tighten.
• Solvent damage may cause vacuum lines to become
soft. Vacuum lines damaged by oil and/or other
solvents may collapse when the engine is running
effectively closing the passage inside the line.
• Install secondary high voltage leads.
Check Coolant Level
• Engine must be off and cold.
• NEVER REMOVE THE PRESSURE CAP ON A HOT
ENGINE.
• The coolant level should be equal to the "COLD"
mark on the coolant recovery tank. Periodically
remove the cooling system pressure cap and check
coolant level inside system. The coolant level should
be equal to the sealing surface of the pressure cap.
If level is low replace pressure cap and repair any/all
other leaks.
• On closed systems visually inspect the coolant
recovery tank and hoses for physical damage
G424 Service Manual
18
Maintenance
Replace LP Fuel Filter Element
Park the lift truck in an authorized refueling area with
the forks lowered, parking beake applled and the
transmission in NEUTRAL.
5
4
3
1
2
6
4. Remove cover (5), magnet (4), spring (3) and
filter element (2) from bottom cover (1).
5. Replace the filter element (2).
6. Check bottom cover O-ring seal (6) for damage.
Replace it if necessary.
7. Install the filter element (2), spring (3), magnet
(4) and cover (5) on bottom cover (1). Align the
scribe line on the covers.
1. Close the fuel shutoff valve on the LP-Gas tank.
Run the engine until fuel in the line runs out and the
engine stops. Turn off the ignition switch and
disconnect switch (if equipped).
8. Install the cover retaining screws. Tighten the
screws in a sequence opposite each other.
9. Open the fuel valve by slowly turning the valve
counterclockwise.
10. Crank the engine only enough to produce a
vacuum at the fuelock. Turn the ignition key
switch off.
11. Check the fuel lines and fittings for leaks with a
soap solution. Make repairs if necessary.
Test Fuel Lock (Electric)
• Start engine.
• Locate electrical connector for fuel lock.
• Disconnect electrical connector.
• Engine will run out of fuel and stop in a short period
of time. (The length of time increases with any
increase in distance between the fuel lock and the
pressure regulator).
2. Scribe a line across the filter housing covers.
3.Remove the cover retaining screws.
G424 Service Manual
19
Maintenance
Replace Gasoline Fuel Filter
(Gasoline Truck and Dual
Fuel Truck)
Inspect Complete Exhaust
System for Leaks, Damage
• Perform visual inspection of exhaust system.
• Repair any/all leaks found.
WARNING
Fuel leaked or spilled onto hot surfaces or
electrical components can cause a fire.
Engine Control Unit(ECU)
and others
(Low Emission LP Truck)
Turn the disconnect switch OFF if fitted or
disconnect the battery when changing fuel
filters
The commander, oxygen sensor and vacuum control
solenoid are not serviceable. If faulty, they must be
replaced. See Trouble Shooting Section
1
3
2
1. Raise the hood and seat assembly.
2. Loosen Bolt(1) and clamps(2)(3).
3. Replace old fuel filter with new filter.
4. Fasten Bolt(1) and clamps(2)(3).
Inspect Gasoline Carburetor
See, gasoline carburetor in Gasoline fuel system
section.
Inspect Pressure
Regulator/Vaporizer
See, pressure regulator/vaporizer in LP fuel system
section.
Inspect LP Mixer
(Standard LP Truck)
See, LP mixer in LP fuel system section.
Inspect Variable Venturi
Air/Fuel Mixer
(Low Emission LP Truck)
See, Variable Venturi Air/Fuel Mixer in LP fuel
system(Low emission version) section.
G424 Service Manual
20
Maintenance
Maintenance Schedule
Interval Hours
Daily
CHECK POINT
Every
Every
Every
Every
Every
250hrs 500hrs 1000hrs 2000hrs 1000hrs
or
or
or
or
or
a month 3 months 6 months a year 18 months
General Maintenance Section
Test fuel system for leaks
Prior to any service of maintenance activity
Inspect engine for fluid leaks
O
Check engine oil and filter
O
Change engine oil and filter
O
Inspect accessory drive belts
O
Inspect electrical system
O
Inspect all vacuum lines and fittings
O
Inspect all fuel fittings and hoses
O
Replace timing belt and counter balance shaft belt.
Check engine compression pressure
Engine Coolant Section
Check coolant level
O
Change coolant
O
Inspect coolant hoses for leaks, cracks swelling, or deterioration
O
Engine Ignition Section
Inspect battery for case damage and corroded Cables
O
Inspect ignition system
O
Check ignition timing-adjust as necessary
O
Replace spark plugs
O
Fuel Lock-Off/Filter Section
Replace LP fuel filter element
O
Replce gasoline fuel filter
O
Inspect lock-off and filter for fuel leaks
O
Ensure lock-off stops fuel flow when engine is off
O
Pressure Regulator Section
Test regulator pressures
O
Inspect pressure regulator for oil build-up
O
Inspect pressure regulator assembly for fuel/coolant leaks
O
Carburetor Section
Check for air leaks in filter system
O
Check for vacuum leaks on complete intake system
O
Inspect air/gas valve assembly
O
Inspect air/fuel mixture throat
O
Inspect gasoline carburetor
O
Check air cleaner indicator
O
Inspect air cleaner
O
Replace air filter element
O
Engine Exhaust Section (Low Emission Version only)
Inspect exhaust manifold for leaks
O
Inspect manifold-to-catalyst exhaust piping and Connections for leaks
O
Inspect catalyst inlet and outlet and leaks
O
G424 Service Manual
21
O
O
Maintenance
ENGINE SYSTEM
Engine Overview
The cylinder blocks are made of the special cast iron
and employ 5-bearing, deep skirt system.
The cylinder heads have hemisphere combustion
chambers, are of cross flow type arranged with V-type
valves and high efficient combustion is intended.
G424 Service Manual
The camshaft is located on the top of the cylinder
heads and driven by cog type timing belt.
Dual type exhaust manifold is employed in order to
reduce output loss by exhaust interference.
22
Engine System
Gasoline Engine
G424 Service Manual
23
Engine System
LPG Engine ( Low Emission Version)
G424 Service Manual
24
Engine System
Timing System
The timing belt is meshed with the sprockets, the
crankshaft sprocket becomes the drive sprocket, and
thus functions to drive the camshaft and oil pump.
Timing belt
The timing belt is the cogged type, using rubber as its basic
material, and it employs a high-strength glass fiber core
which does not expand or contract.
The features of the cogged-type belt compared to a chin are
no expansion/contraction, low noise level, no necessity for
lubrication, light weight, etc.
G424 Service Manual
25
Engine System
Silent Shaft Mechanism
The silent shaft mechanism function mainly to
eliminate, by the action of the silent shafts
incorporated at both sides of the cylinder block, the
vertical vibromotive force of the engine as well as the
vibromotive moment in the rolling direction, thus
making possible quieter operation of the vehicle.
The two silent shafts are arranged as shown in the
G424 Service Manual
figure below. The right silent shaft rotates in the same
direction as the crankshaft, and the left silent shaft
rotates in the opposites direction. Both of these silent
shafts rotate at speed twice that of the crankshaft.
Right silent shaft is driven by timing belt B, and the left
silent shaft is driven by drive gear.
26
Engine System
Auto Lash Adjuster
Construction
These engines have auto lash adjusters that eliminate
the need for valve clearance adjustment and reduce
noises of the valve system. The auto lash adjuster
automatically absorbs change in the valve clearance
caused by engine temperature change or wear of
parts and adjusts the valve clearance always to zero.
Operation of Auto Lash Adjuster
(1) At Start of Valve Lift
When the cam lifts up the rocker arm, the hydraulic
pressure immediately forces the ball in the high pressure
chamber against the seat, closing the high pressure
chamber.
(2) During Valve Lift
A small amount of oil leaks from the high pressure
chamber through a clearance between the body inside
and the plunger outside.
(3) At end of Valve Lift
The plunger spring forces the body back to the initial
position and oil is supplied to the high pressure chamber
to make up for the leaked oil.
G424 Service Manual
27
Engine System
Intake and Exhaust System
Gasoline Engine
The intake manifold employs the shape having good
intake performance.
The exhaust manifold employs a dual type and intend
the reduction of output loss due to exhaust
interference.
G424 Service Manual
28
Engine System
LPG Engine (Low Emission Version)
G424 Service Manual
29
Engine System
Electrical System
Wiring Diagram
(Gasoline Engine)
Stating motor is of the gear reduction type.
Distributor is of a breakerless type and employs the
ignition advancer which uses jointly centrifugal type
and vacuum type.
G424 Service Manual
30
Engine System
Wiring Diagram (LPG Engine, Low Emission Version)
G424 Service Manual
31
Engine System
STARTING SYSTEM
General Description
The starting motor is used to turn the engine flywheel
fast enough to make the engine run. The starting
motor has a solenoid. When the ignition switch is
activated, voltage from the electrical system will cause
the solenoid to move the pinion toward the flywheel
ring gear of the engine. The electrical contacts in the
solenoid close the circuit between the battery and the
starting motor just before the pinion engages the ring
gear. This causes the starting motor to rotate. This
type of motor "turn on" is a positive shift starting motor.
When the engine begins to run, the overrunning clutch
portion of the pinion drive prevents damage to the
armature caused by excessive speeds. The clutch
does this by breaking the mechanical connection. The
pinion will stay meshed with the ring gear until the
ignition switch is released. A return spring in the
overrunning clutch returns the clutch to its rest
position.
G424 Service Manual
32
Starting System
1
2
START
SWITC.H
WH
START
RELAP
W
X
3
4
RD/WH
MTR
BAT
STARTER
MOTOR
BATTERY
5
Typical 12 Volt Starting Circuit
(1) Test point. (2) Test point. (3) Test Point. (4) Test Point. (5) Test Point. (X) Hold-in coil. (W) Pull-in coil.
Diagnosis Procedure
2. Is a high current switch rated about 1000 amps that
actually turns on the starting motor.
The following simplified procedure is intended to help
the serviceman determine if a starting motor needs to
be removed and replaced or repaired. It is not
intended to cover all possible problems and
conditions, but to serve only as a guide. The most
common 12 volt circuit is shown and discussed.
The starting motor solenoid has two coils. Pull-in coil
(W) draws about 40 amps and hold-in coil (X) requires
about 5 amps. The instant the start relay closes, both
coils (W) and (X) receive power. Battery voltage is
applied to the high end of both coils, at test point (3)
which is the start (S) terminal. The low end of hold-in
coil (X) is permanently grounded to the ground post or
motor housing of the starting motor. Grounding for the
low end, test point (4), of pull-in coil (W) is momentary,
and takes place through the DC resistance of the
starting motor. As soon as magnetic force builds in
both coils, the pinion moves toward the flywheel ring
gear. The pinion will stop short of engagement of the
flywheel ring gear. Only then will the solenoid contacts
close to power the starting motor. This temporarily
removes the ground from pull-in coil (W), and puts
battery voltage on both ends of it while the starting
motor cranks. During this period, the pull-in coil is out
of the circuit. Cranking continues until power to the
solenoid is broken by releasing the ignition switch.
General Information
All starting systems are made up of four elements.
They are the ignition switch, start relay, the starting
motor solenoid and starting motor.
Start switches are relatively low current devices. They
are rated to switch approximately 5 to 20 amps.
Because the coil of a start relay [between test point (1)
and (2)] draws about 1 amp, the start switch can easily
turn on the start relay and have long life.
The switch contacts of a typical start relay are rated to
switch 30 amps. Because the solenoid requires 5 to 20
amps the start relay can easily switch this load.
The starting motor solenoid has two functions:
1. Engages the pinion with flywheel.
G424 Service Manual
33
Starting System
The result of these switches and relays is to permit a
5 amp dash-mounted switch to turn on a 500 to 1000
amp motor used to crank an engine.
If the starting motor cranks real slow or does not crank
at all, do the following procedure:
1. Measure battery voltage at the battery posts with
the multimeter while cranking or attempting to crank
the engine. Make sure to measure the battery
posts. Do not measure the cable post clamps.
Battery voltage (power) available during cranking
varies according to the temperature of the batteries.
The following chart is a guide as to what to expect
from a normal system.
2. Is battery voltage equal to or greater than shown in
Figure 1?
TYPICAL SYSTEM VOLTAGE DURING CRANKING
AT VARIOUS AMBIENT TEMPERATURES
Temperature
12V System
-23 to -7 C (-10 to 20 F)
6 to 8 Volts
-7 to 10 C (20 to 50 F)
7 to 9 Volts
10 to 27 C (50 to 80 F)
8 to 10 Volts
I
I
If the battery voltage is correct, go to Step 3.
If the battery voltage is too low, Charge or replace
the battery.
NOTE: A low battery can be caused by battery
condition or a shorted starting motor.
Figure 1
3. Measure current draw on the (+) battery cable
between the battery and the starting motor solenoid
with the clamp-on ammeter. The maximum current
draw allowed is 350 Amp. At temperatures below
27°C (80°F), the voltage will be less and the current
draw will be higer. If current draw is too much, the
starting motor has a problem and must be removed
for repair or replacement.
The next chart shows maximum acceptable voltage
loss in the high current battery circuit feeding the
starting motor. These values are maximums for
machines of approximately 2000 SMH and up. Newer
machines would be less than those shown.
MAXIMUM ACCEPTABLE SYSTEM VOLTAGE
DROPS DURING CRANKING
Circuit
12V System
Battery(-) post to starting motor
(-) terminal
0.7 Volts
Battery (+) post to solenoid (+) terminal
0.5 Volts
Solenoid Bat terminal to
solenoid Mtr terminal
0.4 Volts
NOTE: If voltage at the battery post is within
approximately 2 volts of the lowest value in the
applicable temperature range of Figure1 and if the
large starting motor cables get hot, then the starting
motor has a problem and the Ammeter test is not
needed.
4. Measure starting motor voltage from test point (4) to
(5) with the multimeter while cranking or attempting
to crank the engine.
Figure 2
Voltages greater than those shown are most often
caused by loose and/or corroded connections or
defective switch contacts.
5. Is voltage equal to or greater than shown in Figure
1?
Diagnosis Procedure
I
If the starting motor voltage is correct, the battery
and starting motor cables down to the motor are
within specifications. Go to Step 8.
TOOLS NEEDED
Digital Multimeter or Equivalent
1
DC Clamp-On Ammeter or Equivalent
1
I
If the starting motor voltage is low, the voltage drop
between the battery and the starting motor is too
great. Go to Step 6.
NOTICE
Do not operate the starting motor for more than 30
seconds at a time. After 30 seconds, the cranking
must be stopped for two minutes to allow the starting
motor to cool. This will prevent damage to the starting
motor due to excessive heat buildup.
G424 Service Manual
6. Measure the voltage drops in the cranking circuits
with the multimeter. Compare the results with
maximum voltage drops allowed in Figure 2.
34
Starting System
7. Are all the voltages within specifications ?
Start Relay Tests
I
I
If the voltage drops are correct, go to Step 8, to
check the engine.
D167422 Relay
1. Put the multimeter on the 200 ohm scale.
If the voltage drops are too high, repair and/or
replace the faulty electrical component.
2. Put the multimeter lead to the 85 and 86 terminals.
8. Rotate the crankshaft by hand to make sure it is not
locked up. Check oil viscosity and any external
loads that would affect engine rotation.
3. The indication on the meter must be 82 L 5 ohms.
If the indication is not correct, the start relay must
be replaced.
9. Is the engine locked up or hard to turn ?
4. Put the multimeter leads to the 30 and 87 terminals.
I
I
5. The indication must be "OL"(Over Load). If the
indication is not correct, the start relay must be
replaced.
If it is, repair the engine as required.
If the engine is not hard to turn, go to Step 10.
10. Does the starting motor crank?
6. Connect WH wire to 86 and BK wire to 85 terminal
with the ignition switch to start position. Put the
meter lead to 30 and 87 terminal.
I
I
If it does crank, remove the starting motor for repair
and/or replacement.
7. The indication must be Zero ohm. If the indication is
not correct the start relay must be replaced.
If it does not crank, check for blocked engagement
of the pinion and flywheel ring gear.
NOTE: Blocked engagement and open solenoid
contacts will give the same electrical symptoms.
G424 Service Manual
35
Starting System
Starter Motor
Planetary Gear Reduction Drive Type
The starter motor is small in size light weight and highoutput type.
Rotation of the motor are reduced by the reduction
gear, and high torque is transmitted to the pinion gear.
Operation
1. When the ignition key (IG-SW) is turned to the “ST”
position, current flows from the S terminal of the magnetic
switch to the pull-in coil and the holding coil.
Current from the pull-in coil passes through the M terminal,
flows to the starter’s brush, commutator, and armature,
and then the armature begins to gently turn.
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36
Starting System
2. The plunger of the magnetic switch is then attracted, and
the pinion is pushed out by the shift lever, meshing with the
ring gear.
As a result of the movement of the plunger, the contacts of
the magnetic switch close, and, as a result, the starter is
turned by the high current from the battery directly to the B
terminal, and the engine is activated.
When the contacts closes, the current flowing to the pull-in
coil stops flowing, and the magnetic force decreases. At
this time, what prevents the pinion from being returned by
the return spring is the magnetic force of the holding coil.
When the engine starts and the pinion is caused to rotate
by the ring gear, there is a possibility of damage, and for
that reason an over-running clutch is provided so that the
rotation from the engine is not transmitted.
3. Because the contacts are still closed at the moment when
the ignition key is turned to OFF, current from the battery
flows in the reverse direction from the M terminal and
through the pull-in coil, thus offsetting the magnetic force
of the holding coil, with the result that the pinion is returned
by the return spring, and the contacts are opened.
Construction of planetary gear type reduction drive
This reduction drive consists of a gear on the front end of the
armature shaft, three pinion gears, a gear shaft that supports
three pinion gears and work as the output shaft and the
internal gear that is fixed to the starter motor body. The unit
is called the simple planetary gear set.
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37
Starting System
When the internal gear is fixed as in the case of the starter
motor, the carrier rotates in the same direction as the sun
gear.
This may be used to determine the reduction ratio easily.
.
Namely, the carrier reduction ratio = (43 + 11) / 11 =. 4.9
Permanent magnet pole
Conventionally, the field coil wound around the pole is
energized to generate magnetic fluxes. This system uses a
permanent magnet (ferrite magnet) for the pole, eliminating
the field coil and reducing the size and weight.
The auxiliary pole helps generation of magnetic fluxes to
ensure stable rotation and output characteristics.
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38
Starting System
Removal and Installation
Removal steps
1. Bolt
2. Starter
6EN0867
Inspection
Pinion Gap Adjustment
(1) Disconnect the field coil wire from terminal M of the
magnetic switch.
(2) Connect a 12 V battery between terminal S and
starter motor body (positive terminal to terminal S).
S
Caution: This test must be performed quickly (in less
than 10 seconds) to prevent the coil from burning out.
Stopper
Pinion gap
Pinion
(3) Set switch to “ON”, and pinion will move out.
(4) Check pinion to stopper clearance (pinion gap)
with
a
thickness
gauge.
Pinion gap: 0.5 to 2.0 mm (0.0197 to 0.0787 in.)
6EN1918
(5) If the pinion gap is out of specification, adjust by
adding or removing gaskets between magnetic
switch and front bracket.
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39
Starting System
Pull-in Test of Magnetic Switch
S
(1) Disconnect field coil wire from terminal M of magnetic
switch.
(2) Connect a 12V battery between terminal S and terminal M.
M
Caution: This test must be performed quickly (in less than 10
seconds) to prevent coil from burning.
Disconnect
connector
6EN0871
(3) If pinion moves out, then pull-in coil is good. If it doesn’t.
replace magnetic switch.
Hold-in Test of Magnetic Switch
(1) Disconnect field coil wire from terminal M of magnetic
switch.
(2) Connect a 12V battery between terminal S and body.
S
Caution: This test must be performed quickly (in less than 10
seconds) to prevent coil from burning.
Disconnect
connector
6EN0872
(3) Manually pull out the pinion as far as the pinion stopper
position.
(4) If pinion remains out, everything is in order. If pinion
moves in, hold-in circuit is open. Replace magnetic
switch.
Return Test of Magnetic Switch
(1) Disconnect field coil wire from terminal M of magnetic
switch.
(2) Connect a 12V battery between terminal S and body.
M
Caution: This test must be performed quickly (in less than 10
seconds) to prevent coil from burning.
Disconnect
connector
6EN0873
(3) Pull pinion out and release. If pinion quickly returns to its
original position, everything is in order. If it doesn’t,
replace magnetic switch.
Caution: Be careful not to get your fingers caught when
pulling out the pinion.
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40
Starting System
Free Running Test
Variable resistance
M
Ammeter
Starter
motor
Battery
12
Voltmeter
6EN0874
(1) Place starter motor in a vise equipped with soft jaws and
connect a fully-charged 12-volt battery to starter motor as
follows:
(2) Connect a ammeter (100-ampere scale) and carbon pile
rheostat in series with battery positive post and starter
motor terminal.
(3) Connect a voltmeter (15-volt scale) across starter motor.
(4) Rotate carbon pile to full-resistance position.
(5) Connect battery cable from battery negative post to
starter motor body.
(6) Adjust the rheostat until the battery voltage shown by the
voltmeter is 11V.
(7) Confirm that the maximum amperage is within the
specifications and that the starter motor turns smoothly
and freely.
Current: max. 60 amps
Symptom
Possible cause
Current is too large, and starter motor
rotates at too low speeds.
( Motor output torque is insufficient.)
•Contaminated or oil stained metal
•Friction between armature core and pole piece
•Armature coil and/or field coil not properly grounded
•Armature coil short-circuited
Current is too large, and motor does
not rotate at all.
•Electromagnetic switch not properly grounded
•Armature coil and/or field coil not properly grounded
•Seizure of metal
No current is available, and motor
does not rotate.
•Armature coil and/or field coil open-circuited
•Brush and/or pigtail open-circuited
•Poor contact of brush and commutator due to contaminated
commutator, high mica, etc.
Current is too small, and motor rotates
at low speed. (Motor output torque is
insufficient.)
Loose field coil connections (If the shunt coil alone is
open-circuited or loosely connected, the motor will
rotate at a high speed.)
Current is too large, and motor rotates at
too high speeds. (Motor output torque is
insufficient.)
Field coil short-circuited
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41
Starting System
Disassembly And Reassembly
6EN1917
A
B
B
G424 Service Manual
Disassembly steps
1. Screw
2. Magnetic switch
3. Screw
4. Screw
5. Rear bracket
6. Brush holder
7. Brush
8. Rear bearing
9. Armature
10. Yoke assembly
11. Ball
C
C
42
A
A
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
Packing A
Packing B
Plate
Planetary gear
Lever
Snap ring
Stop ring
Overrunning clutch
Internal gear
Planetary gear holder
Front bracket
Starting System
Maguetic switch
Disassembly Service Points
“S” teminal
A
“B” terminal
“M” terminal
Fieldcoid wire
6EN0610
Disconnect the field coil wire from terminal M of the magnetic
switch
B
Armature/ball removal
Caution: When removing the armature, take care not to lose
the ball (Which is used as a bearing) in the armature end.
C
Socket
Magnetic switch removal
Snap ring/stop ring removal
(1) Press stop ring off snap ring with a suitable socket.
Stop ring
Pinion gear
Armature
Overrunning
clutch
6EN0611
(2) Remove snap ring with snap ring pliers and then remove
stop ring and overrunning clutch.
Snap ring
Pinion
gear
Overrunning
clutch
Snap ring
pliersa
Armature
6EN0612
Cleaning of Starter Motor Parts
Do not immerse the parts in cleaning solvent. Immersion of
the yoke, field coil assembly and/or armature will damage to
insulation.
Do not immerse the drive unit cleaning solvent.
Overrunning clutch is pre-lubricated at the factory and
solvent will wash lubricant form clutch.
The drive may be cleaned with a brush moistened with
cleaning solvent and wiped dry with a cloth.
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43
Starting System
Inspection
1. Commutator
(1) Place the armature on a pair of V-blocks and check the
runout using a dial gauge.
Standard value: 0.5 mm (0.020 in.)
Limit: 0.1 mm (0.004 in.)
1EN0298
(2) Check the outer diameter of the commutator.
Standard value: 29.4 mm (1.16 in.)
Limited: 28.8 mm (1.13 in.)
1EN0302
(3) Check depth of the undercuts between the segments.
Standard value: 0.5 mm (0.020 in.)
Limited: 0.2 mm (0.008 in.)
Under cut
Segment
Mica
1EN0296
2. Overrunning Clutch Check
Free
(1) While holing clutch housing, rotate the pinion. Drive
pinion should rotate smoothly in one direction, but should
not rotate in opposite direction. If clutch does not function
properly, replace overrunning clutch assembly.
(2) Inspect pinion for wear or burrs. If pinion is worn or
burred, replace overrunning clutch assembly. If pinion is
damaged, also inspect ring gear for wear or burrs.
3. Front And Rear Bracket Bushing Check
Inspect bushing for wear or burrs. If bushing is worn or
burred, replace front bracket assembly or rear bracket
assembly.
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44
Starting System
4. Brush
Wear
limit
line
(1) Brushes that are worn beyond wear limit line, or oil
soaked, should be replaced.
(2) When replacing ground brush, side the brush from brush
holder by prying retainer spring back.
1EN0292
5. Armature Coil Short Circuit Test
(1) Place armature on a growler.
(2) Hold a thin steel blade parallel and just above while
rotating armature slowly in growler. A shorted armature
will cause blade to vibrate and be attracted to the core.
Replace shorted armature.
6EN0600
6. Armature Coil Ground Test
Check the insulation between ground commutator segment
and the armature coil core. If there should be no continuity.
6EN0601
7. Armature Coil Open Circuit Check
Check the continuity between segments. If there should be
continuity.
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45
Starting System
Reassembly Service Points
A
Stop
Stop ring/snap ring Installation
Using a suitable pulling tool, pull overrunning clutch stop
ring over snap ring.
Overrunning
Stop ring
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46
Starting System
CHARGING SYSTEM
Alternators
General Description
The alternators used on these engines have three
phase, full-wave, rectified output. They are the brush
type. Refer to the Alternator Coverage chart for
detailed systems operation information
The alternator is an electrical and mechanical
components driven by a belt from engine rotation. It
is used to charge the storage battery during the
engine operation. The alternator is cooled by an
external fan mounted behind the pulley. The fan pulls
air through the holes in the back of the alternator.
The air exits the front of the alternator, cooling it in
the process. The Daewoo CS-121 series also has an
internal fan. This fan is mounted on the rotor. This
fan pulls air through the holes in the back of the
alternator to cool the rectifier bridge and regulator.
The air exits the front of the alternator.
ALTERNATOR COVERAGE
The alternator converts mechanical and magnetic
energy to alternating current (AC) and voltage. This
process is done by rotating a direct current (DC)
electromagnetic field (rotor) inside a three phase
stator. The alternating current and voltage (generated
by the stator) are changed to direct current by a
three phase, full wave rectifier system using six
silicone rectifier diodes. Some alternators have three
exciter diodes or a diode trio. They rectify the current
needed to start the charging process. Direct current
flows to the alternator output terminal.
Alternator
Manufacturer/
Part Number
Series
D167411
Daewoo/CS-121
D187478
MICO/K1 Sealed
IDES081P
Daewoo CS-121 Alternator
A solid state regulator is installed in or on the back of
the alternator. Two brushes conduct current, through
two slip rings, to the rotor field. Some alternators
have a capacitor mounted on them. The capacitor
protects the rectifier from high voltages. It also
suppresses electrical noise through a radio, if
equipped.
The alternator is connected to the battery through the
ignition switch for alternator turn on . Therefore,
alternator excitation occurs when the switch is turned
on.
IDES082P
Mico K1 Enclosed Alternator
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47
Charging System
D187478
Daewoo CS-121 Series
1
1
2
IDES044S
IDES043S
D167411
Rated voltage..................................................12 volts
Polarity is negative ground.
Rotation is clockwise.
Output at 6500 rpm (cold) .............................61 amps
Output voltage ...................................14.0 L 0.5 volts
(1) Torque for battery terminal nut.......3.6 L 0.8 NIm
(32 L 7 lbIin)
(2) Torque for pulley nut ...100 L 7 NIm (75 L 5 lbIft)
IDES045S
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48
Charging System
Remove & Install Alternator
NOTE : Hood, seat and dry air cleaner have been
removed for photographic purposes.
2
1
1. Disconnect wire (1) and wire (2)
3
5
4
2. Remove bolt and washer (3), and remove belt (4).
3. Remove alternator (5).
NOTE : For the installation of the alternator, reverse
the removal steps.
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49
Charging System
IGNITION SYSTEM
Breakerless Ignition System
Ignition System Schematic
(1) Battery. (2) Ignition switch. (3) Coil. (4) Distributor. (5) Spark Plug.
The ignition system has battery (1), ignition switch (2),
coil (3), distributor (4) with inner electronics
circuits and spark plugs (5). The battery and ignition
switch have terminals and closed contacts to permit
battery current flow through the ignition system. These
components
must
have
closed
current
connections to complete the operation of the ignition
circuit. Coil (3) and spark plugs (5) are of the standard
type. The ignition coil changes the low voltage current
into high voltage current to make a spark at the gap of
the spark plug. The coil has two windings around a
G424 Service Manual
soft iron core. The primary has a small number of turns
of heavy wire, and the secondary has many thousand
turns of a very fine wire.
The primary winding is on the outside of the secondary
windings.
50
Ignition System
Distributor
The distributor is the contactless type and is equipped
with a centrifugal advancer and vacuum advancer.
The distributor is installed at the front side surface of
the cylinder head, and is driven directly by the
camshaft.
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51
Ignition System
Governor advance mechanism
In the figure below, pin A rotates together with the
shaft. A governor weight is installed to this pin A.
There is a pin B on the governor weight which fits into
the oblong hole in the cam base. The governor spring
is attached to the spring hook of the governor weight,
pulling the governor weight to the fully closed position.
When the rotation speed increases, the governor
weight is subjected to centrifugal force which causes it
to open outward. When the centrifugal force becomes
stronger than the tensile force of the spring, the weight
opens, as shown by (b) in the figure below, thus
maintaining a balance with the force of the spring.
Because pin B of the weight is fit into the oblong hole
In the cam base, the movement of pin B becomes
rotation of the cam in the direction of rotation. In other
words, the cam advances in relation to the shaft.
When the rotation speed becomes sufficiently high,
pin B contacts the outer side of the oblong hole in the
cam base, and the weight opens no further. This
position is the fully advanced condition.
When the rotation speed decreases, the centrifugal
force of the weight becomes weaker and the weight is
closed by the force of the spring, thus returning to the
original condition.
The advance characteristic of the centrifugal-advance device
employed by the governor is as shown in the figure at the left.
Point A is the beginning of advance, and point B shows the
rotation speed at full advance.
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52
Ignition System
Vacuum advance mechanism
There is a diaphragm within the vacuum controller,
with a spring at the negative-pressure (vacuum) side
which pressure against the diaphragm. A link is
attached to the diaphragm and is connected to the
pickup plate. The pickup assy is installed on the
pickup plate, and can rotate together with the pickup
plate.
The negative pressure (vacuum) side of the vacuum
controller is connected to the vacuum port of the
carburetor by a tube.
When the throttle valve of the carburetor is closed, the
engine is in the idling condition, and there is no
vacuum inside the tube at this time. When the throttle
valve is partially open, the air within the tube is drawn
out by the air/fuel mixture flowing near the vacuum
port, thus resulting in a negative-pressure (vacuum)
condition. Because the tube is connected to the
negative-pressure (vacuum) port of the vacuum
controller, the diaphragm pressure against the spring,
and it moves in the direction of the arrow. Then the
link rotates the pickup plate and, because the position
of the pickup changes, the timing also changes. The
direction is the direction opposite to the direction of
signal rotor rotation, so that the projection of signal
rotor will pass the pickup quickly. In this way, then, the
ignition timing advances.
The figure at the left shows the advance characteristic curve
of the vacuum-advance mechanism. Point A is the start of
the advance, and point B is the end of the advance.
Because the magnitude of the degree of advance determined
by balance of the strength of the vacuum and the pressure of
the spring, if the spring is weak the degree of advance will be
great at a small vacuum.
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53
Ignition System
Removal and Installation
Removal steps
1. Drive belt
2. Water pump pulley
3. Crankshaft pulley
4. Spark plug cable
5. Spark plug
6. High tension cable
G424 Service Manual
A
54
7. Vacuum
8. Ignition
9. Harness
10. Distributor
Ignition System
Inspection
High voltage
terminal
Ignition Coil
Perform the following measurements. Replace the ignition
coil if the standard values are not met.
–
+
1EN0393
(1) Measure the resistance values of the primary and
secondary coils and of the external resistor with a tester.
If the readings are within the standard limits, it follows that
there is no short or open circuit in the ignition coil.
Standard value:
Primary coil resistance value: 1.08 to 1.32 Ω
Secondary coil resistance value: 22.1 to 29.9Ω
Spark Plug Cable/High Tension Cable
(1) Check the caps and covering for cracks.
(2) Measure the resistance values:
Standard value: 16 kΩ/m
Installation Service Points
A
Distributor installation
(1) Turn the crankshaft so that No. 1 cylinder is at top dead
center.
(2) Aligh the distributor housing and gear mating marks.
(3) Shift 1 tooth of gear to meet the pin with the mating mark
of distributor housing as shown in the illustration.
(4) Install the distributor to the engine while aligning mating
of distributor housings (groove) of the distributor’s
installation flange with the center of the distributor
installation stud.
(5) Removes distributor cap and confirms that the rotor
becomes as shown in the illustration.
(6) When the rotor is not in this position, redo from the
operation in step (2).
G424 Service Manual
55
Ignition System
Disassembly and Reassembly
A
G424 Service Manual
Disassembly steps
1. Distributor cap
2. Rotor
3. Cover
4. Signal rotor
5. Pickup coil assembly
6. Ignitor
7. Heat sink
8. Breaker assembly
9. Snap ring
10. Vacuum control
11. Connector assembly
12. O-ring
13. Distributor housing
56
Ignition System
Inspection
Pickup Coil
(1) Using a tester, check the resistance of the pickup coil.
Standard value: 420 to 540Ω
1EL0052
(2) Check to make sure the pointer of the tester oscillates
when the tip of a screwdriver is moved past by the core of
the pickup col assembly.
1EL0053
Signal rotor
Reassembly Procedure
A
Pickup coil assembly installation
Check the air gap between the signal rotor and pickup
assembly.
Standard value: 0.35 to 0.45 mm (0.0138 to 0.0177 in.)
1EL0054
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57
Ignition System
GASOLINE FUEL SYSTEM
General Description
The fuel pump pulls the fuel from fuel tank. The fuel
flows through filter, which is installed on top of the fuel
tank, to carburetor where the fuel is mixed with air at
the correct ratio. This air and fuel mixture then goes to
the inlet manifold. The air and fuel mixture takes in
heat and is completely changed to vapor as it goes
through the inlet manifold to the combustion chamber
of each cylinder. The fuel pump keeps a supply of fuel
to the carburetor at all conditions of operation and
speeds of operation. The output of the fuel pump is
controlled by the needs of the engine.
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58
Gasoline Fuel System
Gasoline Carburetor - Operation
Construction of Carburetor
(1) Float. (2) Front chamber cover. (3) Primary inner venturi. (4) Choke valve. (5) Accelerator pump nozzle. (6) Idle compensator.
(7) Membrane cover. (8) Enrichment jet. (9) Plug. (10) Throttle body. (11) Primary throttle valve. (12) Mixture adjusting screw.
(13) Bypass screw. (14) Primary main jet. (15) Body. (16) Pump inlet ball. (17) Pump lever. (18) Fuel cutoff solenoid.
(19) Pump outlet ball. (20) Primary pilot jet. (21) Valve weight. (22) Needle valve. (23) Fuel screen.
The carburetor is of the two-barrel, downdraft type
which performs well in every engine operation
ranging from slow idle to full speed.
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59
Gasoline Fuel System
1. Air system
Air passed through the air cleaner flows through the choke
bore and venturi into the clearance of the throttle valve and
supports idle running of the engine.
When engine speed increases to off-idle and more, intake
air is metered by the venturi. Air flow to be fed to the
cylinders is controlled by the throttle valve.
2. Float system
Float System
G424 Service Manual
The float maintains a constant fuel level in the float
chamber. Fuel from the fuel tank is pumped out by the fuel
pump and filtered by the strainer. Then, fuel enters the
float chamber through a needle valve.
With entrance of fuel in the float chamber, the float moves
up gradually. At last, the float pushes the needle valve to
shut off the fuel inlet.
When the fuel level lowers, the float moves down and
releases the needle so that the fuel inlet is opened. With
repetition of up-and-down movement of the float, fuel in
the float chamber is kept at an almost constant level during
engine operation.
60
Gasoline Fuel System
3. Idle system
This system provides adequate air-fuel-mixture
richness for smooth engine running ranging from slowidle to light-load operation.
Fuel from the float chamber is sent through the main
jet to the pilot jet where metering of fuel is made.
On the other hand, air entering the venturi air leak and
that entering the pilot air jet No.2 join at the pilot air jet
No.1 where metering of air is made. As a result of
metering, fuel mixes with air and flows through the airfuel-mixture passage to the pilot outlet. The flow of airfuel-mixture is adjusted properly by the bypass screw
and enters the air horn through the bypass hole or the
pilot outlet. It mixes with the small amount of air that
gets past the closed or slightly opened throttle valve.
The final mixture flows into the engine cylinders.
The mixture adjusting screw is used for adjusting the
G424 Service Manual
richness of air-fuel-mixture necessary for good idling.
The bypass screw is for the purpose of adjusting the
flow of primary air-fuel-mixture to the bypass hole so
as to provide sufficient mixture richness mainly for
engine operation ranging from “off idling” to a part of
medium-load operation.
The fuel cutoff solenoid in the idle system functions as
follows : When the key switch is turned to ON, the
solenoid attracts the needle valve to open the fuel feed
line. When the key switch is turned to OFF, the needle
valve protrudes to cut off the fuel feed line, thus
preventing spontaneous running of the engine which
is overheated.
61
Gasoline Fuel System
Idle Compensator
Main Metering System
The idle compensator uses a bimetal. When the
carbretor ambient temperature rises during idle or
“off idle” running, the bimetal bends enough to open
the compensator valve. Now additional air from the
choke bore can flow through the auxiliary air
passage to the intake manifold directly. It leans out
the mixture enough to make up for the proper
richness.
Fuel metered by the main jet is bled by air from the
main air jet and enters the bleed pipe through its
holes. The fuel is discharged from the main nozzle
and sucked by engine cylinders.
If percolation of fuel arises along the main well,
gasoline vapor can escape from the main air jet
through the relatively wide outside of the bleed
pipe. This prevents liquid fuel from spurting from the
main nozzle, thus assuring stable engine operation
and easy restarting.
To prevent percolation due to conduction of heat
from the engine, sufficient cooling of the float
chamber periphery is taken into consideration in
design of the carburetor.
4. Main metering system
The wider the throttle valve opens, the faster the air
flow in the venturi and the greater the vacuum in the
inner venturi will be. As the vacuum becomes
greater, additional fuel is discharged from the main
nozzle.
The main metering system is provided with the
bleed valve press-fitted to the inner venturi and the
main air jet.
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62
Gasoline Fuel System
5. Enrichment system
Enrichment and Accelerator-Pump systems
The enrichment system provides additional fuel
feed to the main metering system during highspeed large-torque operation.
This system use the membrane (diaphragm) which
is actuated by the intake manifold vacuum and
membrane spring to open or close the fuel feed
line.
During partial-throttle operation, a large manifold
vacuum is applied to the vacuum chamber through
the vacuum line and acts on the membrane to close
the valve against the membrane spring force.
When the throttle is opened wide, manifold vacuum
decreases.
This allows the membrane spring to open the valve.
Now, more fuel from the float chamber is metered
by the enrichment jet and can flow through the
valve into the primary main line leading to the main
metering system.
membrane is pushed by the pump lever linked to
the throttle valve and forces fuel to flow under
pressure. When the engine is decelerated, the
membrane is pushed back by the spring and the
pump chamber is refilled with fuel.
Pump delivery decreases with engine speed from
which acceleration is starred. It does not deliver fuel
at all when the angle of throttle valve from the idling
position exceeds the preset angle.
7. Stating system
The starting system consists of the choke valve,
lever assembly, choke connecting rod, and choke
operating lever. This system is provided for feeding
a very rich air-fuel mixture to the engine when the
engine is started (until the engine warms up) or
when a temporary increase of output is needed
during engine operation. When the engine is cold,
some throttle opening must be maintained so that
the engine idles faster then it would when warm.
This is done with “fast idle.” With the fast idle, the
choke valve is closed while the throttle valve is held
at a partially opened position most suitable to
warming-up run.
6. Accelerator-pump system
Rapid opening of the throttle for acceleration allows
a sudden inrush of air. Thus there is a sudden
demand for additional fuel. To provide this extra
fuel, the accelerator-pump system can feed fuel
immediately under pressure.
Fuel from the inlet check valve is sent to the pump
nozzle through the outlet check valve by
reciprocating movement of the membrane. The fuel
is then injected into the main bore.
When the engine is accelerated quickly, the
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63
Gasoline Fuel System
Removal and Installation
6EN1893
A
G424 Service Manual
Removal steps
1. Return set hose assembly
2. Oil seal
3. Air horn
4. Gasket
5. Carburetor
6. Air governor
7. Gasket
B
64
A
8. Fuel pipe
9. Fuel hose
10. Fuel pipe
11. Fuel pump
12. Gasket
13. Insulator
14. Push rod
Gasoline Fuel System
Removal Service Points
A
Carburetor removal
(1) Hold the carburetor in a level position while using care not
to let fuel spill, remove it from the intake manifold.
(2) Turn the carburetor upside down on a pan to drain fuel.
B
Fuel pump removal
Placing the piston in No.1 cylinder at TDC on the
compression stroke makes the fuel pump stroke lift the
smallest, allowing easy removal of the pump.
Installation Service Points
Arm pin Arm
A
Rod spring
Rod
Breather hose
Diaphragm
spring
Diaphragm
Cam shaft
Push rod
Pump body
Pump cover
IN
OUT
6EN0841
G424 Service Manual
Fuel pump installation
(1) Bring the piston in No.1 cylinder to TDC on the
compression stroke. This provides the smallest lift of the
eccentric cam, allowing easy installation of the fuel pump.
(2) Apply engine oil to the surface of the push rod and insert
it into the hole in the cylinder head. Make sure that the
push rod sides smoothly.
(3) Install the fuel pump on the cylinder head with the
insulator and a new gasket in between, and tighten the
bolts completely.
65
Gasoline Fuel System
Gasoline Carburetor
Disassembly and Reassembly
A
A
B
C
C
C
C
D
B
B
A
Disassembly steps
1. Throttle return spring
2. Damper spring
3. Choke rod
4. Screw
5. Float chamber cover
6. Float chamber cover gasket
7. Cover
8. Packing
9. Bimetal
10. O-ring
11. Accelerator wire bracket
12. Float pin
13. Float
14. Needle valve assembly
15. Packing
16. Filter
17. Weight
18. Ball
19. Main jet
20. Screw
21. Screw
22. Accelerator pump cover
23. Diaphragm
24. Spring
25. Fuel cut solenoid
26. O-ring
27. Enrichment
28. Enrichment jet
29. Speed adjust screw
30. Pilot jet
31. Choke lever
32. Spring
33. Main body
34. Insulator gasket
35. Throttle lever
36. Throttle control lever
37. Mixture adjusting screw
38. Throttle body
G424 Service Manual
6En0850
66
Gasoline Fuel System
Service Points of Disassembly
The following parts must not be disassembled at the time of
disassembly.
(1) Choke valve and choke shaft
(2) Inner venturi
(3) Throttle valve and throttle shaft
A
Return spring/choke rod removal
(1) When the spring is removed, avoid prying it with undue
force or any other attempt that can cause damage to it.
(2) Press the end of the choke rod to force the rod out. Avoid
applying a strong force to the plastic grommet of the rod
fit-in hole.
B
Float chamber cover removal
(1) Since the screws require great force to loosen, use a
Phillips screwdriver that exactly fits in the cross recess in
the screw heads.
(2) To remove the float chamber cover, slowly lift it, while
using care not to give damage to the float. Don’t tilt the
main body, as the pump discharge weight and the related
parts may come out and could be lost.
6EN0851
C
Pump weight/ball
Turn the main body upside down to remove the weight and
ball.
D
Main jet
Main jet removal
To remove the main jet, be sure to use a screwdriver whose
tip exactly fits in the slot of the jet.
6EN0852
G424 Service Manual
67
Gasoline Fuel System
Inspection
1. General Inspection
Check the following and repair or replace parts if faulty.
(1) Check fuel passages (jets) and air passages (jets or
orifices) for clogging. If clogged, wash thoroughly with
cleaning solvent or detergent and remove dirt by
compressed air. Do not use wire or other metal pieces.
(2) Check diaphragms, O-rings and springs for damage and
cracks.
(3) Check that needle valve operates lightly. If the valve is
hard to operate or is binding, repair or replace. If there is
overflow, poor valve to seat contact is suspected. Check
thoroughly.
(4) Check the fuel inlet filter (located above the needle valve)
for clogging and damage.
(5) Check the float operation. Check float and lever for
deformation and damage and replace if necessary.
(6) Check operation of the throttle valve, choke valve and
link. If they do not operate lightly, wash well and apply
engine oil sparelingly to their shaft.
(7) Check the float chamber cover and main body for
damage and cracks.
2. Fuel Cut Solenoid Valve Operation Check
(1) Connect the battery directly to the body and terminal of
the fuel cut solenoid valve to apply the voltage.
Caution: Use care not to short-circuit the battery.
(2) Listen to a click which should be heard when the valve
operates normally at the moment the battery is
connected.
12V
6EN0853
3. Fuel Cut Solenoid Valve Resistance Check
Measure the resistance between the body and the terminal of
the fuel cut solenoid valve with a tester.
Standard value:
Approx. 90Ω [at 20°C (68°F)]
6EN0854
G424 Service Manual
68
Gasoline Fuel System
4. Inspection of Mixture Adjusting Screw (MAS)
Check tapered end of mixture adjusting screw (MAS) for
damage from over tightening, etc.
Check for damage
6EN1888
5. Throttle Body Check
Make sure that the throttle shaft moves smoothly. If any sticky
movement is found, thoroughly clean the shaft, and then coat
it with a small amount of engine oil. Do not disassemble the
shaft unnecessarily.
6EN0855
Service Points of Reassembly
For reassembly, reverse the order of disassembly while
paying much attention to the following:
(1) Clean every parts with clear cleaning oil before
reassembly. Check all passages for clogging.
(2) Replace all the removed packings and gaskets.
(3) Make sure the throttle and choke linkage operates
smoothly. If any sticky movement is found, clean or
replace the linkage, and make sure that the carburetor
operates without any problem.
A
Main jet
Installation of main jets
(1) When replacing a main jet, the oil jet and the new jet must
be of the same size, because the jet is selected after
exact flow measurement by factory. (A size symbol is
stamped on each jet.)
6EN0852
G424 Service Manual
69
Gasoline Fuel System
(2) Main jets have size symbols stamped on their ends for
identification.
Size symbols : 132.5
132.5
Size symbol
6EN0869
B
Weight
Check ball
Check ball/weight installation
Install the acceleration check ball and weight.
C
Float/float pin installation
After the float and float pin have been installed, make sure
that the float is in a level position.
6EN0856
Hole A
3rd Stage
2nd stage
• Strangler spring setting positions
Spring
Setting
Positions
Hole B
If the strangler spring of the choke valve shaft is out of
position, set it correctly in the positions shown in the
illustration.
1st stage
Hole C
6EN0858
G424 Service Manual
70
Gasoline Fuel System
Choke shaft
Inspection and Adjustment After Reassembly
Choke lever
1. Fast Idle Opening
(1) Move the choke lever to place the choke valve in fully
closed position.
6EN0859
(2) Measure the clearance “A” (primary throttle valve to
throttle bore).
Primary throttle
valve
NOTE: Refer to the table in SERVICE SPECIFICATIONS for
the clearance.
Clearance “A”
(drill bit diameter)
6EN1889
Fastidle
adjusting
screw
(3) If the clearance “A” is out of specifications, adjust to the
standard value by the fast idle adjusting screw.
Screw direction
of rotation
Clearance
Remarks
Clockwise
Increases
Fast idle speed
increases
Counterclockwise Decreases
6E0860
Fast idle speed
decreases
2. Choke valve Operation
(1) With the choke valve lever set to its full position, move the
choke valve with a finger to make sure that the choke
valve shaft has not an excessive play and the valve
moves smoothly without sticking.
(2) If the choke valve can not be moved smoothly, clean the
choke valve and the area around it.
(3) If the play of the choke valve shaft is excessive, replace
the float chamber cover.
G424 Service Manual
71
Gasoline Fuel System
3. Ports
(1) Connect a hand vacuum pump and check each port for
clogging.
(2) If clogged, clean the port and then blow air into it.
6EN0861
G424 Service Manual
72
Gasoline Fuel System
LP FUEL SYSTEM
General Description
Electric Fuelock Model
3
6
2
7
.
3
2
1
1
4
5
IDES061P
5
6
LP Fuel System Components
(1) Converter. (2) Fuelock. (3) Carburetor.
(4) Coolant ontlet line
(5) Coolant inlet line. (6) Balance hose.
(7) LP fuel line to carburetor
7
IDES062S
engine coolant that flows in line (5) and out line (4).
Carburetor vacuum activates the converters operation
and the fuel flows to the carburetor through line (7).
From carburetor (3), the vapor fuel goes through the
inlet manifold to the combustion chamber of the
engine. In the combustion chamber, the spark made
by the spark plug will "ignite" (cause to burn) this
vapor. Balance hose (6) keeps the correct air and fuel
mixture in the carburetor when there is some
restriction in the air cleaner.
LP Fuel System Components
The basic components of this liquid petroleum (LP)
fuel system are: the fuel tank, the fuel filter and relief
valve, fuelock (2), converter (1) and carburetor (3).
Liquid fuel is sent to fuelock (2) by the pressure in the
fuel tank, which is approximately 1030 kPa (150 psi).
Fuelock (2) permits fuel flow to the converter when
electrically activated by the oil pressure switch. LP fuel
flows into converter (1), which changes the fuel to a
vapor. The fuel receives heat in the converter from the
G424 Service Manual
73
LPG Fuel System
Electric Fuelock
Converter
Fuelock (2) is electrically activated by an oil pressure
switch. When the engine is stopped, or if the engine oil
pressure gets lower than the pressure for operation,
the oil pressure switch will open. When the oil
pressure switch opens, it will close the fuelock, which
stops the supply of fuel to the converter.
2
3
4
1
5
6
Fuel Filter
7
8
IDES064P
8
Converter Components
(1) LP fuel inlet opening. (2) Primary regulator valve.
(3) Primary valve pin. (4) Fulcrum.
(5) Primary diaphragm with lever. (6) Cover.
(7) Secondary diaphragm. (8) LP fuel outlet opening.
IDES063P
10
9
Fuel Filter
(8) Fuel filter.
1
On electric fuelock models, fuel filter (8) is mounted
near the fuel tank. It cleans the fuel before it gets to
the fuelock and converter.
12
2
IDES065P
1
Converter Vaporized Chamber
(1) LP fuel inlet opening. (2) Primary regulator valve.
(9) Vaporizing chamber. (10) Vapor fuel outlet opening.
(11) Coolant outlet opening. (12) Coolant inlet opening.
3
13
14
8
IDES066P
Converter Primary Components
(3) Primary valve pin. (8) LP fuel outlet opening.
(13) Primary regulator spring. (14) Sensing opening.
G424 Service Manual
74
LPG Fuel System
The converter is a combination regulator and
vaporizer. It receives liquid fuel through opening (1) at
tank pressure from the fuelock. The fuel is available
inside converter vaporizing chamber (9) when
carburetor vacuum is felt in converter opening (8).
When vacuum is not available at the fuelock or
opening (8), primary valve pin (3) puts force on
primary regulator valve (2) that makes a seat against
an inner passage for the fuel inlet. The pin action is
controlled by primary diaphragm with lever (5) and
cover (6). Primary spring (13) is in compression when
vacuum is not available.
The vaporizing chamber decreases LP fuel pressure
from the tank to less than atmospheric pressure.
This expansion of the pressurized liquid fuel into
vapor, can result in freezing. The heat from the engine
coolant increases the temperature of the fuel in
vaporizing chamber (9) from approximately -42°C (-44
°F) to +2 °C (+40 °F)
Fuel Tank
15
1
P0002915
IDES067P
LP Fuel Tank
16
The fuel tank is made of heavy steel. The specific size
of the tank is measured by the design of the lift truck,
desired period of time the lift truck is to be operated
before the tank has to be filled and how near an
available supply of fuel is.
Converter Secondary Components
(1) LP fuel inlet opening. (15) Secondary lever assembly.
(16) Secondary regulator seat.
When the engine is running, the solenoid on the
fuelock allows fuel to flow from the fuelock to
converter opening (1). Vacuum is felt through
converter opening (8) from the carburetor. This vacuum
pulls in secondary diaphragm (7) with the diaphragm
link, which moves secondary lever assembly (15). The
secondary lever assembly moves secondary regulator
seat (16) that opens fuel flow passage in chamber (9).
At the same time, the vacuum flows through sensing
opening (14) that causes primary diaphragm with lever
(5) to pull in. This causes the diaphragm lever to make
a pivot on cover (6) fulcrum (pivot point) (4). Primary
valve pin (3) moves away from primary regulator valve
(2) with the assistance of primary regulator spring
(13).
LP Relief Valve
P0002917
When primary regulator valve (2) is off its seat, fuel is
permitted to flow into vaporizing chambers (9). The
fuel flows around and through the passages of the
vaporizing chambers while the heat through the
converter body is being taken in by the fuel which
causes fuel to vaporize. The heat is a product of the
engine coolant that goes in opening (12) and out
opening (11). The flow of vapor fuel goes out
opening (10) in the converter body, activated by open
secondary regulator seat (16) to fuel outlet opening
(8), through the fuel line to the carburetor.
G424 Service Manual
Relief Valve
When the pressure in the LP fuel system gets too high,
the relief valve releases the pressure to the
atmosphere. The action of the relief valve prevents
damage to the fuel lines and other components of the
fuel system. The position of the valve is in a direction
that the fuel will not get on the operator when the valve is
activated.
75
LPG Fuel System
valve (2) measures the air flow that goes into the
engine, respective to the demands of the engine and
throttle valve (10) position.
The air pressure drop of 1.3 to 2.7 kPa (0.2 to 0.4 psi)
is controlled by metering spring (4) which permits the
force necessary to pull in the fuel into the air flow. LP
gas metering valve (6) is connected to the air valve
and lets in the correct amount of fuel from the LP
converter to mix with the air at any opening of the air
valve.
The carburetor is equipped with two limited mixture
adjustments. Idle air screw (1) directs atmosphere
(air) around the opening of air valve (2). As the idle air
screw is adjusted open, the air valve loses a little more
and causes the gas metering valve to close. The result
will be less fuel in the mixture at idle. The second
adjustment is power mixture adjustment (7). It controls
the fuel mixture when gas metering valve (6) is fully in
the up position. This adjustment is done only when the
engine is at a load condition. A CO meter or exhaust
analyzer is used for the power mixture adjustment.
This adjustment has no effect at idle or in the light load
range.
Carburetor
1
2
3
4
5
6
7
8
9
10
IDES070S
LP Fuel Carburetor Schematic
(1) Idle air screw. (2) Air valve. (3) Diaphragm.
(4) Metering spring. (5) Passage. (6) LP gas metering valve.
(7) Power mixture adjustment. (8) Carburetor. (9) Piston.
(10) Throttle valve.
Lift trucks with LP (Liquid Petroleum) fuel system use
an air valve type of carburetor (8). The operation of the
carburetor controls the fuel mixture flow into the
engine with the movement of throttle valve (10) and
mixes the air flow with the LP fuel flow.
The air flow is measured by the operation of air valve
(2) in the carburetor bowl. The stronger the air flow
through the carburetor, the higher the air valve moves
up. LP gas metering valve (6) is connected directly to
air valve (2). As the air valve moves up, LP gas
metering valve (6) also moves up. LP gas metering
valve (6) is shaped to let in the correct amount of LP
gas at any height related to air valve (2) upper
movement. The air valve activates a pressure drop
which gives a very high metering force (measured
suction) to the fuel that flows in the carburetor at low
engine speeds and it permits easy starting. At full
engine speeds, the air valve is at the top of its upper
movement. The valve then becomes an inverted (up
side down) venturi and will let a large amount of air
pass through.
When starting the engine, the intake stroke of piston
(9) causes lower than atmosphere pressure (vacuum)
in the carburetor. The vacuum is felt through passage
(5) in air valve (2) and in the upper side of diaphragm
(3). As a result, the atmospheric pressure flows in the
carburetor and pushes up on the diaphragm.
Diaphragm (3) is lifted against the down pressure of
metering spring (4). The vacuum that is felt on
diaphragm (3) is variable according to engine speed
and the position of throttle valve (10) opening. Air
G424 Service Manual
76
LPG Fuel System
1. Make sure the setting for ignition timing is correct.
Tests or Adjustments
See Ignition Timing.
Adhere to the following warnings when performing any
tests or adjustments while the engine is running.
2. Connect the Electrical System Analyzer as shown in
Engine RPM Check in the Testing And Adjusting.
WARNING
3. Start and run the engine until the engine reaches
normal operating temperature.
Work carefully around an engine that is running.
Engine parts that are hot, or parts that are moving,
can cause personal injury.
4. Adjust screw (1) to get the correct low idle speed.
5. Check low idle speed. The Correct low idle
speed is: .........................................700 L 25 rpm.
WARNING
Idle Mixture Adjustment
Exhaust fumes contain carbon monoxide (CO)
which can cause personal injury or death. Start
and operate the engine in a well ventilated area
only. In an enclosed area, vent the exhaust to the
outside.
NOTE: The governor and accelerator linkage
adjustments for the LP Fuel System are the same as
those for the Gasoline Fuel System. For Governor and
Accelerator Linkage Adjustments, see Gasoline Fuel
System in the Testing And Adjusting.
2
P0004816
Mixture Adjustment.
(2) Idle mixture Screw
Carburetor Adjustment
Low Idle Speed Adjustment
1. Connect the Electrical System Analyzer to read
engine rpm.
2. Check to be sure the ignition timing is set correctly.
3. Run the engine until normal operating temperature
is reached.
4. Check to be sure the low idle speed is set correctly.
5. Turn idle mixture screw (2) clockwise or
counterclockwise to obtain the maximum smooth
rpm.
1
P0004816
6. Check and readjust (if required) the low idle speed
again.
Low Idle Speed Adjustment
(1) Idle speed screw.
G424 Service Manual
77
LPG Fuel System
Power Mixture Adjustment
CO Meter Method
The method of adjustment depends upon the test
equipment that is available. The power mixture can be
adjusted using a CO meter, vacuum gauge or electrical system analyzer. The CO meter method is the preferred method for reduced emissions. The vacuum
gauge method is the next most accurate method if CO
measuring equipment is not available. The engine
speed method is the easiest but least accurate
method.
The power mixture adjustment must be done with the
engine in a load condition. A CO meter or exhaust analyzer testing equipment must be used to measure the
CO content in the exhaust fumes. To adjust the power
mixture, turn knob either toward the "L" (lean) or "R"
(rich) fuel flow mixture for a 1.0 to 1.5 percent CO indication on the test equipment. Start the adjustment with
knob in the middle position.
NOTE: A lift truck, that does not operate with a heavy
load all the time, can operate efficiently with a leaner
power mixture setting (less than 1.0 to 1.5 percent
CO). This is because the truck will not be in operation
constantly in a load condition for a long period of time.
During heavy load and high speed conditions the lift
truck requires a richer power mixture setting (1.0 to 1.5
percent CO).
L
R
Vacuum Gauge Method
1. Connect the vacuum gauge to the intake manifold.
Start and run the engine until normal operating temperature is reached.
2. Run the engine at high idle. Turn power mixture
knob to the middle position.
Power Mixture Adjustment
(3) Power mixture knob
3. Put a load on the engine by operating the hydraulic
system.
Engine Speed Method
4. Monitor the vacuum gauge reading. Turn power
mixture adjustment knob toward the "L" (lean) position, until the vacuum starts to drop. The correct
mixture is the point at which the vacuum starts to
drop.
1. Connect the Electrical System Analyzer to read
engine rpm.
2. Check to be sure the ignition timing is set correctly.
3. Run the engine until normal operating temperature
is reached.
4. Turn the power mixture knob (3) midway between
lean (L) and rich (R).
5. Accelerate the engine to high idle rpm. Put a load
on engine by holding the tilt cylinder against relief.
6. Turn the power mixture knob toward lean (L) until
engine rpm drops.
7. Turn the power mixture knob toward rich (R) until
the rpm recover.
8. The correct mixture will be that setting just before
the engine rpm drops.
G424 Service Manual
78
LPG Fuel System
Inner Fuel System Leak Check
Fuel System Leak Check
Outer Fuel System Leak Check
3
2
1
WARNING
LP gas is highly flammable. To prevent personal
injury, keep fire and flammable materials away from
the lift truck when work is done on the fuel system.
Combustion gases from LP gas fuel system can be a
danger. To find LP gas leaks, use soap and water
solution or other foaming bubble solvent around fuel
line connections and on other components that
possibly cause LP gas leaks. The soap and water
method is the best, use this method after repair
completion on the fuel system or after the fuel system
has been connected together again.
4
IDES105S
Inner Fuel System Leakage Check (Electric Fuelock).
(1) Converter. (2) Fuelock. (3) Carburetor cover.
(4) Primer button.
Fuel Filter Check
An indication of a dirty fuel filter that needs
replacement is when frost (freezing vapor) is seen on
the filter housing or the housing is very cold to touch.
A dirty filter causes a fuel pressure drop across the
filter, the fuel becomes a vapor and freezes. In this
condition, engine power output decreases because of
the lesser fuel flow. To replace the filter, see the
Operation & Maintenance Manual for the respective
model.
G424 Service Manual
79
LPG Fuel System
Converter Leak Test
6
7
To check the converter for leakage after repair, do the
procedure that follows:
8
1. Put a plug in the fuel outlet openings.
9
10
2. Put compressed air in the fuel inlet openings, up to
a maximum of 725 kPa (120 psi).
3. Wait ten minutes and then check the converter or
fuelock for air leaks. Listen for air to come out
around gaskets or seals.
IDES106P
Carburetor Components (Carburetor Shown Removed For
Better Illustration)
(6) Spring. (7) Backup plate and diaphragm. (8) Air valve ring. (9)
Air-gas valve assembly. (10) Inner carburetor body.
4. If there are no air leaks, then the converter is good.
5. If air does come out, then the converter will have to
be disassembled to find the problem.
1. Remove carburetor cover (3), spring (6), backup
plate and diaphragm (7), air valve ring (8) and
airgas valve assembly (9).
Recommendation For LP Fuel
Systems
2. Slowly turn the LP fuel ON at the tank.
3. Check the inlet fuel jet for fuel flow (leakage) in
carburetor body (10).
In freezing temperature conditions run the engine at
fast idle until the engine coolant temperature is
between 10 to 16˚C (50˚F to 60˚F). A low idle in cold
temperature conditions can damage the engine
because of poor circulation of the engine oil. Running
the engine to move the lift truck short distances and
then stopping the engine without the coolant being
heated can cause the LP fuel to be trapped (cannot be
released) in the converter. As this trapped fuel
changes to a vapor with the engine stopped, this
change causes too much pressure in the converter.
The force from the pressure is put on the primary
regulator valve against its seat. If this occurs often, the
primary regulator valve in the vaporized area of the
converter will be damaged.
4. If the operation of fuelock (2) and converter (1) are
correct, there will be no fuel flow.
5. If there is fuel flow, the leakage problem must be
found either in the fuelock or the converter.
6. Push in primer button (4) on the converter to open
the converter fuel regulator valve.
7. A small amount of fuel will flow through the
carburetor inlet fuel jet as the fuel from fuelock (2)
flows out of the hose.
8. If the operation of fuelock (2) is correct, the fuel flow
will stop as soon as the system is empty.
G424 Service Manual
80
LPG Fuel System
LP Converter - Check, Clean
Test LP-Gas Converter
1. Obtain a test kit.
2. Start engine.
3. Close the liquid outlet valve in the fuel storage
container.
4. Run engine out of fuel.
5. Install the 0-30kPa (0-5 psi) gauge in the primary
test port.
Secondary
Test Port
6.. Install the 0-2.5kPa (0-10 in H O) gauge in the
secondary test port.
Primary Test Port
2
LP-Gas Converter
7. Slowly open the liquid outiet valve in the fuel
storage container.
Inspect Converter for Oil Accumulation
8. Start the engine.
1. Start engine.
9. Operate the engine at idle, part throttle and full
load.
2. Close the liquid outlet valve in the fuel storage
container
10. Observe readings on both gauges.
3. Run engine out of fuel.
11. The primary gauge reading
approximately 10.3kPa (1.5 psi).
should
4. Remove the regulator secondary cover.
be
5. Remove secondary diaphragm.
12. The
secondary
gauge
should
read
approximately negative0.1kPa (0.5 in H O) to
negative 2.5kPa (10 in H O).
6. Remove any concentrations of oil from the
secondary chamber with soap and warm water.
13. If readings are out of specification, as required.
7. If required, replace them with LP converter
service kit.
2
2
8. Apply anti-seize compound to screw threads.
9. Re-assemble regulator in reverse order.
10. Slowly open the liquid outlet valve in the fuel
storage container.
11. Start engine.
12. Perform leak test.
G424 Service Manual
81
LPG Fuel System
Disassembly & Assembly
LPG Carburetor
Remove & Install LP Gas Carburetor
6EN1890
Removal steps
1. Throttle return spring
2. Accel wire assembly
3. Return spring support
4. LPG carburetor
5. Throttle chamber gasket
G424 Service Manual
6. Throttle body
7. Carburetor gasket
8. Air governor
9. Air governor gasket
10. Fuel pump cover
82
LPG Fuel System
Disassemble LP Gas Carburetor
9
Start By:
10
a. Remove LP Gas Carburetor.
11
2
P0004825
8
1
4. Remove power mixture screw (8), idle mixture
screw (9) and the spring. Remove four screws
(10).
Remove throttle body assembly (11) and the
gasket.
P0004821
1. Remove four screws (1) and cover (2).
4
12
P0003003
3
P0004822
5. Remove gasket (12).
2. Remove spring (3). Remove diaphragm assembly
(4).
5
5
6
16
6
13
14
15
7
P0004829
P0003001
6. Remove nut (13).
7. Loosen the bolt and remove stop (16).
3. Remove four screws (5), backup plate (6),
diaphragm (7) and the air valve ring from the inner
carburetor body.
8. Remove two screws (14). Remove throttle plate
(15).
9. Remove shaft assembly (17) from the throttle
body.
G424 Service Manual
83
LPG Fuel System
Assemble LP Gas Carburetor
LP Gas Fuelock
Remove & Install LP Gas Fuelock
1
16
13
14
15
3
P0004829
2
1. Check all parts for damage. Replace damaged
parts with new as necessary.
P0002926
2. Make sure all parts are clean and free of dirt and
foreign material.
1. Disconnect fuel lines (1).
3. Put throttle shaft (17) in position in the throttle
body, and install stop lever (16).
2. Disconnect wire (2).
3. Remove fuelock (3).
4. Put throttle plate (15) in position and install the two
screws.
NOTE: For the installation of the LP gas fuelock,
reverse the removal steps.
Apply loctite PST or equivalent to fuelock pipe
threads before installation.
5. Assemble in reverse order of disassembly.
NOTE : Air valve diaphragm must be oriented with
position mark pointing toward LPG inlet.
6. See Testing & Adjusting for proper test and adjust
procedures.
End By:
a. Install LP Gas Carburetor.
G424 Service Manual
84
LPG Fuel System
Disassembly of LP Gas Converter
LP Gas Converter
Remove & Install LP Gas Converter
1
Start by : Remove LP Gas Fuelock.
1
3
2
IDED048P
3
1. Remove six screws (1), cover (2), and diaphragm
(3) from the converter.
2
P0004817
4
1. Remove lines (1).
5
2. Remove two bolts and nut (2).
3. Remove LP gas converter (3).
NOTE : For the installation of the LP gas converter,
reverse the removal steps.
6
IDED049P
NOTE : When you assemble the elbow on LP
converter, the elbow must be installed on the
converter, keeping the minimum distance shown in the
figure, to prevent contact with the secondary
diaphragm.
2. Remove screw (4), secondary lever (5), the seat,
the pin and the spring (6).
7
6.1 mm
8
Minimum
IDED050P
9
3. Turn the converter body around, remove the seven
screws (7), back cover (8), and the diaphragm (9).
G424 Service Manual
85
LPG Fuel System
10
IDED051P
4. Remove spring and plunger (10) from the
intermediate cover.
13
11
12
IDED052P
1. Screw (6)
5. Remove intermediate cover (11), diaphragm (12)
and the secondary regulator valve (13).
2. Cover Assembly, Secondary
3. Diaphragm Assembly, Secondary
Inspection, Assembly of LP Gas Converter
4. Screw,
1. Clean primary and secondary valves with soap and
warm water and inspect for wear. Replace if
required.
5. Lever, Secondary
6. Pin, Secondary Fulcrum
7. Seat, Secondary
2. Clean primary and secondary diaphragms with
soap and warm water and inspect for wear.
Inspect primary diaphragm lever for straightness.
Replace if required.
8. Spring
9. Body Assembly With Jet
10. Screw (2)
3. Alwasy replace the coolant chamber gasket.
11. Gasket, Body To Body Cover Plate
4. Clean regulator castings with parts cleaning colvent
and inspect. It is very rare for the castings to require
replacement.
12. Pin, Valve Primary
13. Plate, Body Cover
14. Plug
5. Reassemble regulator.
15. Spring, Primary
6. Use an anti-seize compound on screws.
16. E Ring, External
7. Use an approved pipe sealant on fittings.
17. Diaphragm Assembly, Primary
18. Cover, Primary
NOTE: For assembly of the LP gas converter reverse
the disassembly steps.
G424 Service Manual
19. Screw (7)
86
LPG Fuel System
LPG FUEL SYSTEM (LOW EMISSION VERSION)
General Description
Air cleaner
(MAP)
Schematic of G424 LP fuel system (low emission version)
G242 LP engine (Low Emission Version) is different
from standard G424 LP engine. To reduce emission of
exhaust gas, closed loop carburetion system and
catalytic muffler are applied to low emission version
G424 LP engine.
regulate the air/fuel mixtures, correcting for proper
air/fuel. The fuel control valve (FCV) meters air valve
vacuum (AVV) into the atmospheric reference side of
the secondary regulator diaphragm. The atmospheric
reference vent orifice allows for the controlled
depletion of the vacuum over the diaphragm, this
assists the dynamic response of the diaphragm.
Catalytic muffler reduces the emission level in the
exhaust gas. In order to obtain maximum effect from
the catalyst, an accurate control of the air fuel ratio is
required. The engine controller uses an exhaust gas
oxygen sensor (EGO) in the exhaust system to send
information about exhaust gas conent to the controller.
The controller then calculates any correction that may
need to be made to the air fuel ratio. The controller
makes these corrections to the air fuel ratio by
manipulating the inlet fuel pressure to the carburetor
through the fuel control valve (FCV). Reducing the fuel
pressure leans the air/fuel mixfure. Increasing the fuel
pressure richens the air/fuel mixture.
The controller uses engine exhaust gas oxygen
sensors (EGO), engine speed (tachometer signal) and
manifold absolute pressure sensors (MAP), to
G424 Service Manual
87
LPG Fuel System(Low Emission Version)
FUELOCK
VALVE
LP
CONVERTER
LP
CARBURETOR
GOVERNER
MUFFLER
ENGINE
Open-loop LP Carburetion System : G424 LP engine
TACHO
SENSOR
INTAKE
BOOST
FUEL
CONTROL
VALVE
ENGINE
CONTROL
UNIT
(ECU)
OXYGEN
SENSOR
FUELOCK
VALVE
LP
CONVERTER
LP
CARBURETOR
GOVERNER
CATALYTIC
MUFFLER
ENGINE
Closed-loop LP Carburetion System : G424 LP engine (low emission version)
G424 Service Manual
88
LPG Fuel System(Low Emission Version)
ports (9) in the air valve (3). A pressure / force
imbalance begins to build across the air valve
diaphragm (5) between the air valve vacuum chamber
(8) and atmospheric pressure below the diaphragm
(10).
LP Carburetor
(Variable Venturi)
The variable venturi air/fuel mixer is mounted in the
intake air stream between the air cleaner and the
intake manifold. The design of the main section
incorporates a cylindrical bore through the center (1)
and a gas discharge jet (2). Incorporated into the inlet
of the mixer bore is the air valve (3), tapered gas
metering valve (4), air valve diaphragm (5) and
calibrated air valve metering spring (6). The gas valve
(4) is permanently attached to the air valve (3) with a
face seal mounted in between the two parts (the airgas valve assembly is mounted in the center of and
supported by the diaphragm). When the engine is not
running this face seal creates a gas tight seal against
the gas discharge jet (2), with the downward force of
the calibrated air valve spring (6). A throttle valve (7) is
incorporated into the carburetor assembly.
As the negative pressure in the air valve vacuum
chamber (8) reaches setting value of water column the
air valve (3) begins to lift against the pressure of the
calibrated air valve metering spring (6) .The amount of
negative pressure generated is a direct result of
throttle position and the amount of air flowing through
the mixer into the engine. As the air valve (3) rises it
lifts the tapered gas metering valve (4) off its seat and
exposes the gas discharge jet (2) to the negative
pressure signal generated within the mixer bore.
This allows the negative pressure signal to travel to
the secondary vacuum chamber of the pressure
regulator and operate the regulator. I he profile of the
tapered gas valve (4), in conjunction with the regulator
spring, meters out the desired A/F ratio.
A/F mixture at idle is adjusted with a tapered idle
screw (not shown) which is capped at production and
cannot be adjusted. A/F ratio at maximum load is
limited by the fixed main mixture jet (11), which is
sized for the application.
In addition the assembly includes two manifold
sensors, one for switching the ECU control (13)
depending on engine load, and the other for operating
a lock-off solenoid (14). In addition the unit is fitted
with a precisely controlled vacuum port (12) to allow
control of ignition timing by vacuum load control.
6
8
9
3
5
10
4
2
1
11
12
7
13
14
1. Mixer bore
2. Gas discharge jet
3. Air valve
4. Gas valve
5. Air valve diaphragm
6. Air valve spring
7. Throttle valve
8. Air valve vacuum chamber
9. Vacuum transfer ports
10. Atmospheric pressure
11. Fixed main mixture jet
12. Vacuum port
13. Vacuum switch (MAP)
14. Vacuum switch
As the engine is started it begins to draw in air. Since
the air valve (3) is covering the inlet to the mixer bore
a negative pressure begins to build. This negative
pressure signal is communicated to the air valve
vacuum chamber (8) through four vacuum transfer
G424 Service Manual
89
LPG Fuel System(Low Emission Version)
Vacuum Switch (MAP)
Vacuum Switch
1
2
3
1. Electrical
2. Vacuum port
3. Main body
1. Electrical
2. Vacuum port
3. Main body
The vacuum switch is a simple direct acting contact
pressure switch, consisting of a main body (3), an
electrical connector with two pins (1) and a vacuum
port connection (2).
The unit is normally open (i.e. the electrical connectors
(1) are not common) when no vacuum is applied to the
vacuum port (2).
When vacuum is applied to the port (2) unit respponds
and closes the electriccal contacts (1) so that current
may pass.
G424 Service Manual
The vacuum switch is a simple diaphragm unit,
consisting of a main body (3) housing a
diaphragm/spring, two electrical connectors (1) and a
vacuum port connection (2).
The unit is normally open (i.e the electrical connectors
(1) are not common) when no vacuum is applied to the
vacuum port (2).
When vacuum is applied (see specification for limits)
to the port (2) the diaphragm/spring in the body (3)
responds and closes the electrical contacts (1) so that
current may pass.
90
LPG Fuel System(Low Emission Version)
chamber and the primary atmospheric chamber (18)
This causes the primary diaphragm and lever
assembly (9) to pivot (10) against primary spring (3)
pressure, raising primary valve pin (11), closing off the
primary valve (2). Since fuel pressure falls from tank
pressure, a liquid liquefied petroleum gas evaporates.
As this phase change occurs the fuel takes on heat
from the primary heat exchanger chamber of the
regulator (4). This heat is replaced by engine coolant,
which is piped through passage (12) in the heat
exchanger section of the regulator. Fuel will not flow
through the regulator to the carburetor until a negative
pressure signal is received. When the engine is
cranking or running, a negative pressure signal is
generated by the carburetor. This negative pressure
signal is communicated to the fuel outlet (13) and the
regulator secondary vacuum chamber (14). The
negative pressure signal acts upon the lower side of
the secondary diaphragm (15) causing a pressure /
force imbalance across the diaphragm between the
secondary vacuum chamber (14) and the secondary
atmospheric vent chamber (16). When the negative
pressure signal reaches negative setting value the
pressure force imbalance overcomes the secondary
spring force (8) and the secondary diaphragm (9)
moves downward. As the secondary diaphragm
moves it causes the secondary lever (l7) to pivot and
lift the secondary valve (7) off its seat allowing fuel to
flow from the primary heat exchanger chamber (4)
through the secondary chamber (14) and to the
carburetor. Since fuel has now exited the primary heat
exchanger chamber (4) the pressure in the chamber
will drop, allowing the primary valve (2) to re-open.
Whilst fuel is flowing, the calibrated secondary spring
(8) will maintain a relatively constant pressure in the
secondary vacuum chamber (14) and the amount of
fuel flowing will vary depending on how far the
secondary valve (7) opens in response to the negative
pressure signal generated by the carburetor.
For closed loop control, the secondary atmospheric
vent chamber (16) is connected to AVV via a fuel
control valve, thus varying the secondary vacuum
chamber pressure (14) in response to a pulse width
modulated signal provided to the fuel control valve.
LP Converter
15
16
14
17
8
7
13
2
1
11
3
10
5
6
12
9
18
1. Fuel inlet
2. Primary valve
3. Primary spring
4. Primary heat exchanger chamber
5. Pressure transfer port
6. Primary diaphragm chamber
7. Secondary valve
8. Secondary spring
9. Primary diaphragm
10. Primary pivot
11. Primary pin
12. Coolant passage
13. Fuel outlet
14. Secondary vacuum chamber
15. Secondary diaphragm
16. Secondary atmospheric vent chamber
17. Secondary lever
18. Primary atmospheric chamber
Fuel (Propane Liquid), at tank pressure enters the
regulator through the fuel inlet port (1). Propane liquid
then flows through the primary valve (2), which is held
normally open by the primary spring (3), and into the
primary heat exchanger chamber of the regulator (4).
A small transfer port (5) connects the primary heat
exchanger chamber and the primary diaphragm
chamber(6).
The secondary valve (7) at the outlet of the primary
heat exchanger chamber (4) is held normally closed
by the secondary spring (8). Therefore the pressure in
the primary heat exchanger chamber (4) and the
primary diaphragm chamber (6) begins to rise from
atmospheric pressure. When the pressure in the
primary heat exchanger chamber (4) and primary
diaphragm chamber (6) reaches setting value it
causes a pressure/force imbalance across the primary
diaphragm (9) between the primary heat exchanger
G424 Service Manual
91
LPG Fuel System(Low Emission Version)
Fuel Control Valve
Fuel Lock - Off
2
3
1
6EV2142
6EN2139
1.
2.
3.
4.
Carburetor AVV port connection
Vaporizer secondary vent chamber connection
Electrical connectors
Balance line connection
1.
2.
3.
4.
The fuel control valve is a three way valve, operated
by a pulse width modulated electronic signal applied to
the electrical connectors (3) by the fuel system ECU.
With no voltage supplied, the vaporizer secondary
vent chamber connection (2) port is connected to the
balance line connection (4) port and in this state the
pressure in the balance (4) pressure signal is
transferred via (2) to the vaporizer and the carburetor
AVV port (1) is blocked. When a signal is provided to
the electrical connectors (3) the valve opens and
connects the vaporizer secondary atmospheric vent
chamber port (2) with the carburetor will provide a
vacuum signal (AVV) which is therefore ‘pulsed’, into
the vaporizer secondary chamber when port (1) and
(2) are connected (i.e when the valve is energized).
G424 Service Manual
4
Solenoid coil
Fuel inlet connection
Fuel outlet connection
Electrical connector
The fuel lock-off unit is a direct acting plunger style
unit. Fuel is provided to the fuel inlet connection (2)
and passes into the fitter housing, and through the
fitter. With no electrical signal applied to the electrical
connector (4) the unit is normally closed via spring
pressure inside the coil stem acting on the valve seat.
When power is provided to the electrical connector (4),
the coil (1) is energized and lifts the plunger inside the
coil stem against spring pressure, and allows fuel to
flow to the fuel outlet (3).
92
LPG Fuel System(Low Emission Version)
Engine Control Unit (ECU)
6EV2149
In order to obtain maximum emission reductions from
the exhaust gas catalyst, accurate control of the
engines operating air fuel ratio (AFR) is required. The
engine control unit (ECU) uses input from three
sources: excess oxygen information from the exhaust
gas oxygen sensor (EGO), ignition pulses (engine
RPM) and intake manifold pressure (high or low). This
input is used to apply a duty cycle and a rate of
change of that duty cycle to the fuel control valve
(FCV). The duty cycle of the FCV has a direct effect on
the AFR metered by the carburetor and burned by the
engine. ECU algorithms are calibrated for a balance of
optimal engine emissions, drive-ability, power and fuel
consumption.
Within the ECU closed-loop algorithms there are two
sets of calibration tables, one for high and one for low
manifold pressure. The proper table is selected based
on the input from the mechanical calibration of the
manifold pressure switch used. Each of the two tables
contains sixteen columns corresponding to sixteen
engine RPM operating ranges. The proper column is
selected based on engine rpm. These columns each
have eight calibrations that affect the rate of duty cycle
change and allow duty cycle stepping after EGO
voltage crosses the .5 V threshold. The duty cycle
stepping is used for AFR biasing and for rapid
recovery during transient operation. EGO voltage and
time since last EGO switch (across the .5 V threshold)
determine the column calibration to apply to the rate of
duty cycle change. There are additional calibrations
for FCV duty cycle at cold EGO startup and for the
number of ignition inputs per engine revolution.
During operation a normal sequence of events is as
follows:
If the EGO voltage is below .5 V, considered a lean
condition, the controller steps FCV duty cycle to a
lower value, then begins decreasing the FCV duty
G424 Service Manual
cycle at a constant rate. This decreases the flow of air
valve vacuum (AVV) through the FCV to the
secondary reference chamber of the fuel pressure
regulator (sometimes referred to as a vaporizer). This
vacuum is depleted at a relatively constant rate via a
vent orifice referenced to atmospheric pressure,
resulting in a pressure balance proportional to FCV
duty cycle and vent orifice size. The lower flow through
the FCV results in a higher overall chamber Pressure.
Which results in a higher fuel pressure to the
carburetor and a richer AFR. If the duty cycle
continues to lower longer than a calibrated number of
engine revolutions without an EGO switch, a different
calibration is selected resulting in higher rate of duty
cycle change until EGO switch.
The calibration tables determine the step size, rate of
duty cycle change and the number of engine
revolutions without an EGO before going to higher
rate.
If the EGO voltage is above .5 V, considered a rich
condition, the controller steps FCV duty cycle to a
higher value, then begins increasing the FCV duty
cycle at a constant rate. This increases the flow of AVV
through the FCV to the secondary reference chamber
of the fuel pressure regulator. The higher flow through
the FCV results in a lower overall chamber pressure,
which results in a lower fuel pressure to the carburetor
and a leaner AFR. If the duty cycle continues to lower
longer than a calibrated number of engine revolutions
without an EGO switch, a different calibration is
selected resulting in higher rate of duty cycle change
until EGO switch. The calibration tables determine the
step size, rate of duty cycle change and the number of
engine revolutions without an EGO before going to
higher rate.
93
LPG Fuel System(Low Emission Version)
Oxygen Sensor
Cover
Connector
Housing
Lead wire
Sensor device
6EN2146
The oxygen sensor installed on the exhaust manifold
makes use of the principles of a solid electrolyte oxygen
concentration cell. The oxygen concentration cell is
characterized by a sharp change of the output voltage in
the vicinity of the stoichiometric air/fuel ratio.
Electromotive force (V)
Stoichiometric ratio
Rich
Lean
Air/fuel ratio
6EN2144
Using such characteristics, the oxygen sensor senses
the oxygen concentration in the exhaust gas and feeds
it to the engine control unit. The engine control unit then
determines if the air/fuel ratio is richer or leaner as
compared to the stoichiometric ratio and provides
feedback control to adjust the air/fuel ratio to the
stoichiometric ratio where the emission purification rate
of the three-catalyst convector is optimum.
Performance of
Three-Way Catalytic Converter
Operating window for converter
% Conversion
CO
CxHy
NOx
Stoichiometric Point
Air/Fuel Ratio
6EN2145
G424 Service Manual
94
LPG Fuel System(Low Emission Version)
Catalytic Muffler
Performance of
Three-Way Catalytic Converter
Operating window for converter
The catalytic muffler is mounted in the exhaust gas
stream of G430 engine. The catalytic muffler facilitates
oxidation and reduction reactions that reduce the
amount of unwanted constituents in the exhaust gas
stream. Catalytic mufflers have sound deadening and
spark arresting features incorporated into the design.
% Conversion
CO
4
CxHy
3
NOx
Stoichiometric Point
Air/Fuel Ratio
2
1
After combustion the contents of the engine
cylinder(s) are expelled into the exhaust system.
These hot gases next travel to the catalytic muffler.
The catalytic muffler is made up of a shell (1)
incorporating an inlet (2) and an outlet (4). Inside, the
catalytic muffler contains a three-way catalyst section
(3) as well as sound dampening and spark arresting
features. The three-way catalyst section (3) consists of
a honeycomb coated with a mixture of platinum,
palladium and rhodium. The hot exhaust gases enter
the catalytic muffler through the inlet (1). Next the hot
exhaust gases flow through the catalyst section (3)
where an oxidation and reduction reactions take
place. These chemical reactions reduce the amount of
CO, HC and NOx in the engine exhaust. The exhaust
gas then flows through the outlet (4).
Reaction
CO + O = CO
HC + O = H O + CO
NO + CO = N + CO
NO + H = N + H O
NO + HC = N + H O = CO
2
2
2
2
2
X
X
X
2
2
2
2
2
2
2
G424 Service Manual
2
Stage
Oxidation
Oxidation
Reduction
Reduction
Reduction
95
LPG Fuel System(Low Emission Version)
Tests or Adjustments
Adhere to the following warnings when performing any
tests or adjustments while the engine is running.
WARNING
Work carefully around an engine that is running.
Engine parts that are hot, or parts that are moving,
can cause personal injury.
9. When reassembling mixer, locate the notch on
air/gas valve diaphragm to point to fuel inlet.
10. Open the fule storage container liquid outlet
valve solwly.
WARNING
11. Check for leaks.
Exhaust fumes contain carbon monoxide (CO)
which can cause personal injury or death. Start
and operate the engine in a well ventilated area
only. In an enclosed area, vent the exhaust to the
outside.
Check engine idle speed
LP Carburetor-Check, Clean
Check engine low idle speed. If it does not meet
specification, adjust idle speed adjustment screw.
Check and Clean LP Carburetor.
Low idle speed specification : 700+/-25 rpm
12. start engine and verify normal operation.
The LP Carburetor requires periodic inspection,
and cleaning. Inspection and cleaning are as
follows :
1. Start engine.
2. Close the liquid outlet valve in the fuel storage
container.
3. Run engine out of fuel.
1
2
3
4
NOTICE
The idle air/fuel mixture is factory set, therefore, no
further adjusstments are required. The part throttle
air/fuel mixture is factory set, therefore, no further
adjusstments are required. The full power air/fuel
mixture is factory set, therefore no, further
adjustments are required, either.
4. Remove mixer lid (4).
5. Remove air valve (2) and spring (3).
Inspect and lubricate throttle cable linkage every
500 service hours or 3 months.
6. Clean air valve with warm soapy water.
7. Clean mixer throat with approved carburetor
cleaner.
8. Inspect air valve and mixer throat for wear,
repair/replace as required.
G424 Service Manual
96
LPG Fuel System(Low Emission Version)
LP Converter-Check, Clen
Inspection of Vacuum Switch
See, “LP Converter-Check, Clean” in LP Fuel System
Section.
Inspection of Fuel Lock - Off
6EN2132
1. Connect a hand vacuum pump to the nipple of the
vacuum switch.
6EN2135
2. Using a vacuum pump, vacuum (0.7 or more kPa)
is applied to a vacuum sensor, and the existence of
continuity between sensor terminals is checked.
1. When voltage is impressed to the terminal of fuel
lock-off, check whether there si operation sound.
Vacuum gauge
Not applied
0.7 kPa or more
2. If there is an abnormality, replace the fuel lock-off.
Inspection of Fuel Control Valve
Continuity
Non-conductive
Conductive
3. If there is an abnormality, replace the vacuum
switch.
1. Connect a hand vacuum pump to the nipple A of the
vacuum switch.
Inspection of Vacuum Switch (MAP)
6EN2131
6EN2133
2. Battery voltage is impressed between the terminals
of a fuel control valve, a hand vacuum pump is
connecting in nipple A, and vacuum is applied.
1. Connect a hand vacuum pump to the nipple of the
vacuum switch.
Items
When current is flowing
2. Using a vacuum pump, vacuum (24 or more kPa) is
applied to a vacuum sensor, and the existence of
continuity between sensor terminals is checked.
When B nipple is closed
Vacuum is felt with a finger.
When Current is not flowing Vacuum is not felt with a finger.
Vacuum gauge
Not applied
24 kPa or more
3. If there is an abnormality, replace the fuel control
valve.
Continuity
Non-conductive
Conductive
3. If there is an abnormality, replace the vacuum
switch.
G424 Service Manual
97
LPG Fuel System(Low Emission Version)
Inspection of Oxygen Sensor
Blue code
White code
Oxygen
sensor
side
(1) Before checking, warm up the engine until engine
coolant temperature reaches 80 to 95°C
(2) In the state where engine is poerated disconnent the
oxygen sensor connector and connect a voltmeter.
Caution
The right measurement cannot be pertormed if oxygen
sensor connector is separated before engine starting
(3) Measure the oxygen sensor output voltage.
Standard value : 0.6 - 1.0V
(4) If there is a deviation from the standard value,
replace the oxygen sensor.
G424 Service Manual
98
LPG Fuel System(Low Emission Version)
Disassembly & Assembly
LPG Carburetor
Removal and Installation of LP Gas Carburetor
7
6EN2143
Removal steps
1. Bracket - Accel Wire
2. LPG Carburetor
3. Carburetor Gasket
4. Air Governor
5. Governor Gasket
6. Fuel pump Cover
7. Bolt
G424 Service Manual
99
LPG Fuel System(Low Emission Version)
Disassembly & Assembly of LP Gas Carburetor
6EN2147
Removal steps
1. Bolt
2. LPG mixer
3. Gasket
4. Vacuum switch
5. Fitting
6. Vacuum switch (MAP)
7. Idle adjustment screw
8. Idle adjustment screw spring
9. Throttle body assembly
G424 Service Manual
100
LPG Fuel System(Low Emission Version)
LP Gas Converter
Removal & Installation of LP Gas Converter
6EN2148
Removal steps
1.
2.
3.
4.
5.
6.
7.
8.
9. Vacuum terminal
10. Balance hose
11. Jet
12. Elbow fitting
13. Elbow fitting
14. Fuel outlet plug
15. Bolt washer assembly
16. Converter
Vacuum hose
Vacuum hose
Vacuum hose
Fuel control valve
LPG shut off valve assembly
Balance hose
Check valve elbow fitting
Balance hose
Disassemble & Assemble of LP Gas Converter
See, “Disassembly & Assembly” of LP Fuel System
Section.
G424 Service Manual
101
LPG Fuel System(Low Emission Version)
DUAL FUEL SYSTEM
1
2
3
5
4
6
7
8
9
10
11
12
13
14
IDES071S
Dual Fuel Basic Schematic
(1) Gasoline inlet line (from gasoline tank). (2) Mechanical fuel pump. (3) LP mixer. (4) Balance hose. (5) LP electric fuelock. (6) LP
fuel line. (7) Gasoline electric fuelock. (8) Converter. (9) Selector switch. (10) Carburetor. (11) Elbow. (12) LP fuel line. (13) LP fuel
filter. (14) LP fuel inlet line (from LP tank).
The dual fuel system is a combination of the gasoline
and the liquid petroleum fuel systems. This system
allows the operator to run the engine on gasoline or
liquid petroleum fuel.
fuelock (7) is stopped, which closes fuelock (7) and
shuts off the gasoline supply to the carburetor.
When selector switch (9) is turned to the LP position, LP
fuelock (5) opens and LP fuel flows through line (14),
filter (13) and to converter (8). The converter changes
the fuel to a vapor. This vapor flows through line (12) to
mixer (3). The mixer sends the vapor through elbow (11)
to the gasoline carburetor, which now acts as a throttle
plate. From the carburetor, the vapor goes through the
inlet manifold to the combustion chamber of each
cylinder.
The basic components of the dual fuel system are the
LP and gasoline fuel tanks, mechanical fuel pump (2),
selector switch (9), gasoline carburetor (10), LP mixer
(3), converter (8), LP fuelock (5), LP fuel filter (13),
gasoline fuelock (7) and the connecting fuel lines.
When selector switch (9) is in the gasoline position,
gasoline fuelock (7) is open. Gasoline is drawn through
line (1), the fuel filter and fuel pump (2), fuelock (7) and
into the carburetor, where the fuel is mixed with air at the
correct ratio. The air and fuel mixture fuel then goes to
the inlet manifold and is changed to a vapor. It then goes
to the combustion chamber of each cylinder.
Balance hose (4) between the atmospheric opening in
the converter and the mixer keeps the correct air and
fuel mixture in the mixer when there is some restriction
in the air cleaner.
NOTE: Refer to the topics Gasoline Fuel System and
Liquid Petroleum Fuel System for the operation of the
components not explained here.
To change from gasoline to LP fuel, selector switch (9)
should first be put in the OFF position. This is done to
allow the gasoline in the line and the carburetor to be
used before LP fuel is started. When selector switch (9)
is turned OFF or to the LP position, power to gasoline
G424 Service Manual
102
Dual Fuel System
GOVERNING SYSTEM
General Description
Sectional View of Air Governor
(1) Body. (2) Stabilizer rod. (3) Stabilizer piston. (4) Throttle plate. (5) Throttle plate shaft. (6) Bearing. (7) Nipple. (8) Spring.
(9) Bush nut. (10) Adjusting screw. (11) Plate. (12) Cam
The air governor is located to the underside of the
carburetor. It serves to protect the hydraulic pump, to
limit the maximum traveling speed of the vehicle, and
to prevent excessive increase of engine speed.
2. Auxiliary operation
The throttle plate opening angle of this governor is
set under the full-open condition of the carburetor.
Accordingly, when the carburetor throttle valve is
operated in the direction of closing, governor
pressure applied to the throttle plate decreases
and, therefore, the throttle plate is rotated by the
spring in the direction of opening. As a result,
engine speed increases. To prevent this, the
governor is provided with a stabilizer piston.
1. Governing operation
The throttle plate shaft is offset from the center of
the governor bore. Also, the full-open position of
the throttle plate does not coincide with the truly
full-open position, but rather leans to the closing
side. Therefore, the pressure of mixture flow acts
on the throttle plate to rotate it in direction of
closing, causing a torque to its shaft.
The stabilizer piston acts to close the throttle plate
when a large vacuum pressure is developed on
the upper side of the throttle plate, so that proper
opening of the throttle plate can be maintained in
combination with the opening of the carburetor
throttle valve. With the help of this auxiliary
operation, the governing operation can follow up
the variations of load quickly.
The torque stretches the return spring attached to
the cam on the throttle plate shaft until the torque
balances the tension of the spring, and the throttle
plate is maintained at that open angle.
This is governing operation. That is, a balance
between the pressure applied to the throttle plate,
which depends on vacuum pressure, and the
spring tension keeps the throttle plate at position
between the full-open position and the full-close
position to control the amount of mixture flowing
into the engine.
G424 Service Manual
103
Governing System
Air Governor
Disassembly and Reassembly
6EN0862
A
A
A
B
Disassembly steps
1. Ventilation hose
2. Gasket
3. Sealing cap
4. Cover plate assembly
5. Gasket
6. Adjusting nut
7. Adjusting screw
8. Plate assembly
9. Valve assembly
10. Valve shaft assembly
11. Piston cover
12. Gasket
13. Stabilizer piston
14. Piston shaft
15. Governor body
G424 Service Manual
Disassembly Service Points
Caution: Since the air governor has been adjusted and sealed
in the manufacturer’s factory to conform to the specifications, it
should not be disassembled in general cases. Like any other
sealed components, the air governor should not be
disassembled anywhere except the locations where a warranty
claim decision is authorized. In addition, the cam on the throttle
valve shaft should never be removed.
104
Governing System
Inspection
Piston shaft
Stabilizer
piston
Valve
1. Check the plate assembly (8) composed of a ribbon spring
and coil spring for cracks and any other damage.
2. Check the valve shaft for wear, and also make sure that it
rotates smoothly when mounted in the body.
3. Check the piston for damage. Check also the valve fit-in
section of the shaft for damage.
4. Grease packed needle bearings are press-fitted at both
ends of the valve shaft hole of the governor body. Avoid
cleaning the body in gasoline or any other solvent.
Section A-A
Valve
Screw
Adjusting nut
Reassembly Service Points
Caution: Thoroughly clean all component parts before
installation. Do not apply grease or oil anywhere in the body
except the needle bearings (grease packed) in the throttle
valve shaft hole.
A
Adjusting screw and nut setting
When assembling the air governor separately from the
engine, temporarily assemble it so that the throttle valve will
be in the fully opened position.
Governor Adjustment
See,Adjustment and Troubleshooting Section.
G424 Service Manual
105
Governing System
LUBRICATION SYSTEM
General Description
Cam shaft
Oil pressure
switch
Oil filter
Crankshaft
Oil pump
Oil pan
Oil pickup
Lubricating system is the full-flow filtered pressurefeed oil system and the oil reserved in the oil pan is
fed with pressure to each part of engine. After the oil
pressure is adjusted through the relief valve, the oil is
fed to the cylinder blocks and cylinder head.
In the cylinder head the oil is forcibly fed to the
camshaft journals, rocker arm pivots and further cam
surfaces.
G424 Service Manual
OIl Filter
106
Lubrication System
NOTE : In normal case, the recommended engine oil
for G424 engine is SAE 10W - 30.
Testing & Adjusting
Adhere to the following warnings when performing any
tests or adjustments while the engine is running.
But, if the excessive valve noise occurs up to five
minutes after a cold start and if the maximum ambient
temperature is lower than 10°C (50°F), it is
recommended to change engine oil to SAE 5W - 30 for
that application.
WARNING
Work carefully around an engine that is running.
Engine parts that are hot, or parts that are moving,
can cause personal injury.
Synthetic Oils
Synthetic engine oils are not recommended for use in
G424 Engine. Synthetics may offer advantages in
cold-temperature pumpability and high-temperature
oxidation resistance.
However, synthetic oils have not proven to provide
operational or economic benefits over conventional
petroleum-based oils in G424 Engine. Their use does
not permit the extension of oil change intervals.
WARNING
Exhaust fumes contain carbon monoxide (CO) which
can cause personal injury or death. Start and operate
the engine in a well ventilated area only. In an
enclosed area, vent the exhaust to the outside.
Lubrication System Problems
Engine Oil
One of the problems in the list that follows will
generally be an indication of a problem in the
lubrication system for the engine.
Engine Oil Recommendation
IToo much oil consumption.
ILow oil pressure.
IHigh oil pressure.
IToo much component wear.
The following oil specifications provide the guidelines
for the selection of commercial products :
Use gasoline engine oil. Recommended API service
classification is class SJ grade.
Too Much Oil Consumption
NOTICE
IEngine outside oil leakage
Failure to follow the oil recommendations can cause
shortened engine life due to carbon deposits or
excessive wear.
Check for leakage at the seals at each end of the
crankshaft. Look for leakage at the oil pan gasket and
all lubrication system connections. Check to see if oil
comes out of the crankcase breather. This can be
caused by combustion gas leakage around the
pistons. A dirty crankcase breather will cause high
pressure in the crankcase, and this will cause gasket
and seal leakage.
Prior to changing oil, select an oil based on the
prevailing daytime temperature in the area in which
the engine is operated. The chart in figure is a guide to
selection the proper crankcase oil.
IMPORTANT : Oils containing “solid” additives, nondetergent oils, or low-quality oils are not
recommended for use in G424 Engine.
ICombustion area oil leakage
Oil leakage into the combustion area of the cylinders
can be the cause of blue smoke. There are three
possible ways for oil leakage into the combustion area
of the stems.
Barometric temperature
1. Oil leakage between worn valve guides and valve
stems.
SAE 15W-40
2. Worn or damaged piston rings, or dirty oil return
holes.
SAE 10W-30
SAE 5W-30
3. Compression ring and/or intermediate ring not
installed correctly.
Engine Oil Viscosity Recommendation
G424 Service Manual
107
Lubrication System
NOTE: Too much oil consumption can also be the
result if oil with the wrong viscosity is used. Oil with a
thin viscosity can be caused by fuel leakage into the
crankcase, or by increased engine temperature.
When some components of the engine show bearing
wear in a short time, the cause can be a restriction in an
oil passage. A broken oil passage can also be the cause.
If an oil pressure check is done and the oil pressure is
correct, but a component is worn because it does not
get enough lubrication, look at the passage for oil
supply to that component. A restriction in a supply
passage will not let enough lubrication get to a
component and this will cause early wear.
Low Oil Pressure
1
2
3
4
5
6
7
ILOO001P
Instrument Panel
(1) Engine Oil Light
Before starting the engine, the engine oil light(1) on
the instrument panel will turn on when the key switch
is turned to the ON position. The light will turn off after
the engine is started and while the engine is running,
lidicating normal oil pressure. The light will turn on
during operation only when there is insufficient engine
oil pressure to properly lubricate the engine’s internal
paarts.
If the oil light comes on, indicating the pressure is low,
check for the causes that follow:
1. Low oil level in the crankcase.
2. Defect in the oil pressure indicator light or oil
pressure sensor unit.
3. Restriction to oil pump screen.
4. Leakage at the oil line connections.
5. Worn connecting rod or main bearings. Worn gears
in the oil pump.
6. Oil pressure relief valve worn or stuck in the OPEN
position.
7. Oil filter bypass valve stuck open. Oil filter is
restricted. Replace oil filter.
High Oil Pressure
Oil pressure will be high if the oil pressure relief valve
in the oil pump cannot move from the closed position.
Too Much Component Wear
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108
Lubrication System
Oil Pressure Check
2
1
Oil Pressure Check
(1) LP pressure switch. (2) Oil pressure switch.
(two-terminals)
(one-terminal)
1. With the engine OFF, make sure the oil level is
correct. Connect the analyzer to the engine as
shown in Engine RPM Check in the Testing And
Adjusting.
WARNING
Before the LP/oil pressure switch is removed, the
engine must be stopped. Make sure oil pressure is
released to prevent personal injury.
2. Remove LP pressure switch (1) or oil pressure
switch (2). Install the pressure gauge in adapter.
3. Start the engine and allow it to warm up to normal
operating temperature.
4. Run the engine at 2000 rpm. Read the pressure
gauge.
5. The oil pressure must be approximately 200 kPa
(29 psi) at 2000 rpm. There is no adjustment to the
oil pressure relief valve.
For the possible cause see Lubrication System
Problems in Troubleshooting.
NOTE: A lower pressure indication, 50 kPa (7 psi), is
normal at low idle speed.
For changing Engine Oil and Filter, See Maintenance
Section
G424 Service Manual
109
Lubrication System
COOLING SYSTEM
General Description
1
2
5
3
6
8
7
9
10
Cooling System Schematic
(1) Cylinder head. (2) Thermostat. (3) Recovery tank. (5) Radiator top hose. (6) Radiator pressure cap.
(7) Cylinder walls. (8) Radiator. (9) Radiator lower hose. (10) Water pump.
Water pump (10) is installed on the front of the
cylinder block. The water pump is driven by a single V
belt from the crankshaft pulley. The inlet opening of
the water pump is connected to the radiator lower
hose (9). The outlet flow from the water pump goes
through passages inside the cylinder block.
will go through radiator top hose (5) and into the top tank
of radiator (8). Coolant then goes through the cores of the
radiator. The air from the fan will make the coolant cool as
the coolant flows to the bottom of the radiator and out
hose (9) where the coolant returns to water pump (10).
The radiator is equipped with a shroud to increase the
efficiency of the fan and cause the air to be pushed
through the radiator and away from the lift truck.
The coolant from the water pump through the
cylinder block passages has primary coolant flow to
and around the seats for the exhaust valves. This method
gives the coolant with the coolest temperature flow to the
hottest area during engine operation.
If the coolant is hot and the cooling system pressure is
too high, some coolant flows to the top of radiator (8)
through the tube to recovery tank (3). The cooling
system pressure is controlled by cap (6). When the
cooling system pressure goes above its rated pressure, a
valve opens in pressure cap (6) which releases the
cooling system pressure to the atmosphere. After the
engine is at normal temperature for operation, a
development of vacuum is present in the cooling
system. Pressure cap (6) permits air in the radiator to
remove the vacuum at the same time coolant from
recovery tank (3) is pulled back into the radiator.
Cylinder walls (7) are cooled by the coolant flow
through the block. After the coolant goes through the
cylinder block it flows through cylinder head (1) to the
thermostat housing, where the bypass type
thermostat (2) is installed. The thermostat controls the
opening to radiator (8) to control the temperature in
the cooling system.
If the coolant is cold (cool), the thermostat will be closed.
The coolant circulates (makes a complete circuit) from the
water pump and through the cylinder block until the
temperature of the coolant is warm enough to make the
thermostat open. When thermostat (2) is open the coolant
G424 Service Manual
110
Cooling System
Testing & Adjusting
4. Look for bent radiator fins. Be sure that air flow
through the radiator does not have a restriction.
Adhere to the following warnings when performing any
tests or adjustments while the engine is running:
5. Inspect the drive belts for the fan.
6. Check for damage to the fan blades.
WARNING
7. Look for air or combustion gas in the cooling system.
Work carefully around an engine that is running.
Engine parts that are hot, or parts that are moving,
can cause personal injury.
8. Inspect the filler cap and the surface that seals the
cap. This surface must be clean.
9. Look for a large amount of dirt in the radiator core
and on the engine.
WARNING
10. Check for loose or missing fan shrouds that cause
poor flow of cooling air.
Exhaust fumes contain carbon monoxide (CO)
which can cause personal injury or death. Start and
operate the engine in a well ventilated area only. In an
enclosed area, vent the exhaust to the outside.
Cooling System Tests
This engine has a pressure type cooling system. A
pressure type cooling system gives two advantages.
The first advantage is that the cooling system can
have safe operation at a temperature that is higher
than the normal boiling (steam) point of water. The
second advantage is that this type system prevents
cavitation (the sudden making of low pressure bubbles
in liquids by mechanical forces ) in the water pump.
With this type system, it is more difficult for an air or
steam pocket to be made in the cooling system.
The cause for an engine getting too hot is generally
because regular inspections of the cooling system
were not made. Make a visual inspection of the
cooling system before testing with testing equipment.
IDES108S
Cooling System Visual Inspection
Remember that temperature and pressure work
together. When making a diagnosis of a cooling
system problem, temperature and pressure must both
be checked. Cooling system pressure will have an
effect on cooling system temperatures. For an
example, look at the chart to see the effect of
pressure and height above sea level on the boiling
(steam) point of water.
WARNING
Do not loosen the filler cap or pressure cap on a hot
engine. Steam or hot coolant can cause severe burns.
1. After the engine is cool, loosen the filler cap (on a
radiator with a pressure cap, turn it to the first stop)
to let pressure out of the cooling system. Then
remove filler or pressure cap.
2. Check coolant level in the cooling system.
3. Look for leaks in the system.
G424 Service Manual
111
Cooling System
Pressure Cap Test
Cooling System Leak Check
To test the cooling system for leaks, use the following
procedure:
A
WARNING
If the engine has been in operation and the coolant
is hot, slowly loosen the pressure cap to the first
stop and let the pressure out of the cooling
system, then remove the pressure cap.
1. Remove pressure cap from the radiator.
2. Make sure the radiator is full (hot) or nearly full
(cold) of coolant.
IDES109S
Pressure Cap Diagram
(A) Sealing surface of cap and radiator.
3. Attach the Cooling System Pressurizing Pump Tool
to the radiator filler neck.
4. Pump the pressure to 20 kPa (3 psi) more than the
rated pressure of the cap.
One cause for a pressure loss in the cooling system
can be a bad seal on the pressure cap of the system.
Inspect the pressure cap carefully. Look for damage to
the seal or the sealing surface. Any foreign material or
deposits on the cap, seal or seal or sealing surface
must be removed.
5. Check the radiator for outside leakage.
6. Check all connections and hoses of the cooling
system for outside leakage.
7. If there is no outside leakage and the pressure
reading on the gauge is still the same after 5
minutes, the radiator and cooling system do not
have leakage. If the reading on the gauge goes
down and there is no outside leakage, there is
leakage on the inside of the cooling system. Make
repairs as necessary
To check the pressure cap opening pressure, do the
following procedure.
WARNING
If the engine has been in operation and the coolant
is hot, slowly loosen the pressure cap to the first
stop and let the pressure out of the cooling
system, then remove the pressure cap.
1. Remove pressure cap from the radiator.
2. Put the pressure cap on the Cooling
System Pressurizing Pump Tool.
3. Look at the gauge for the pressure that makes the
pressure cap open. It must be as follows:
D460972 Cap .................................85 to 110 kPa
(12 to 16 psi)
4. If the pressure cap is bad, install a new pressure cap.
G424 Service Manual
112
Cooling System
Thermostat
The thermostat is the wax pellet type. A jiggle valve
(which improves air bleeding during water supply) is
provided on the flange part. When the thermostat is
closed, the circulation of coolant is stopped, thereby
making warm-up faster.
When the temperature increases further and reaches
a certain specified temperature, the valve opens fully,
allowing even more coolant to circulate through the
radiator.
Thus, in this way the degree of valve opening is varied
according to the temperature of the coolant, and the
temperature of the coolant is adjusted by varying the
amount of coolant caused to circulate through the
radiator.
Operation
Thermostat Test
To test the thermostat opening temperature, use the
following procedure:
WARNING
The pan, water and thermostat will be very hot and
can cause burns. Do not touch the pan, water or
thermostat. Handle the components with an
insulated device for protection.
1. Remove the thermostat from the engine.
2. Hang the thermostat in a pan of water. Put a
thermometer in the water. Put the thermostat
completely under water. Do not let the thermostat
make contact with the pan.
When the temperature of the coolant is low, the valve
is closed by the spring, with the result that the coolant
circulates within the engine, without passing through
the radiator.
When the temperature of the coolant rises and
reaches a certain specified temperature, the valve
opens and the coolant also circulates through the
radiator.
G424 Service Manual
3. Put heat to the pan of water. Make the water in the
pan move around. This keeps all of the water at the
same temperature.
4. The thermostat must start to open when the
temperature is 82°C (180°F). The thermostat must
be fully open at 96°C(205°F).
113
Cooling System
Cooling System Heat Problems
Cooling System Recommendation
To check if there is a good reason for heat problems
do the checks that follow:
Coolant Information
1. The indications of a heat problem are as follows:
a. High coolant temperature indicator light is on or
needle of coolant temperature gauge is in red
range.
b. Coolant boils out (comes out because of too
much heat) of the cooling system during
operations.
c. Coolant boils out on the floor when the engine is
stopped.
d. Coolant must be added at the end of each shift
but Steps b and c are not present.
NOTICE
DAEWOO recommends that the coolant mix contain
50% commercially available automotive antifreeze,
and 50% water.
The coolant mixture of less than 30% concentration
does not provide sufficient corrosion protection.
Concentrations over 60% adversely affect freeze
protection and heat transfer rates.
To prevent damage to your engine, never add coolant to
an overheated engine. Allow the engine to cool first.
If the lift truck is to be stored in, or shipped to, an area
with freezing temperatures, the cooling system must
be protected to the lowest expected outside (ambient)
temperature.
2. If indication in Step 1 a is only present. It is possible
the problem is only a damaged gauge, light or
sender. Make a replacement of the defective part.
3. If indication in Step 1b is present, do the procedure
that follows:
a. Run the engine at medium idle (1200 rpm) for
three minutes after high idle operation. This cools
off the hottest parts of the engine before it is
stopped.
b. Install a coolant recovery system on the truck, if
not already equipped.
The engine cooling system is protected with a
commercially available automotive antifreeze, when
shipped from the factory.
Check the specific gravity of the coolant solution
frequently in cold weather to ensure adequate
protection.
4. If indications in Step 1b, 1c or 1d are present, but
Step 1a is not and the high temperature indicator
light does work, the problem can be a damaged
radiator cap seal or there can be a leak in the
cooling system. Complete the procedure that
follows:
a. Do the Pressure Cap Test, Cooling System Leak
Check, Thermostat Test and Belt Adjustment in
the Testing And Adjusting.
b. Clean the radiator with hot water (steam clean)
at low pressure and use detergent or air
according to the different types of debris that
caused the radiator to be dirty (plugged).
c. Check the engine high idle setting.
Clean the cooling system if it is contaminated, if the
engine overheats or if foaming is observed in the
radiator.
Old coolant should be drained, system cleaned and
new coolant added as recommended with the
commercially available automotive antifreeze.
Filling at over 20 liters per minute can cause air
pockets in the cooling system.
After draining and refilling the cooling system,
operate the engine with the radiator cap removed until
the coolant reaches normal operating temperature and the
coolant
level
stabilizes. Add
coolant
as
necessary to fill the system to the proper level.
NOTE: Another condition that can cause heat
problems is the ignition timing. Retarded (late) timing
causes the engine to send more heat to the cooling
system. Advanced (early) timing causes the engine to
send less heat to the cooling system.
G424 Service Manual
Operate with a thermostat in the cooling system all
year-round. Cooling system problems can arise
without a thermostat.
114
Cooling System
Coolant Water
DAEWOO recommends selecting automotive
antifreeze suitable for gasoline engines using
aluminum alloy parts. The antifreeze should meet
ASTM-D3306 standard.
Hard water, or water with high levels of calcium and
magnesium ions, encourages the formation of
insoluble chemical compounds by combining with
cooling system additives such as silicates and
phosphates.
Make proper antifreeze additions.
The tendency of silicates and phosphates to
precipitate out-of-solution increases with increasing
water hardness. Hard water, or water with high levels
of calcium and magnesium ions encourages the
formation of insoluble chemicals, especially after a
number of heating and cooling cycles.
Adding pure antifreeze as a makeup solution for
cooling system top-up is an unacceptable practice. It
increases the concentration of antifreeze in the
cooling system which increases the concentration of
dissolved solids and undissolved chemical inhibitors in
the cooling system. Add antifreeze mixed with water to
the same freeze protection as your cooling system.
DAEWOO prefers the use of distilled water or
deionized water to reduce the potential and severity of
chemical insolubility.
Acceptable Water
Water Content
Limits (ppm)
Chlorides (Cl)
40 maximum
Sulfates (SO4)
50 maximum
Total Hardness
80mg/MM maximum
Total Solids
pH
250 maximum
6.0~8.0
ppm = parts per million
Using water that meets the minimum acceptable water
requirement may not prevent drop-out of these
chemical compounds totally, but should minimize the
rate to acceptable levels.
Antifreeze
NOTICE
DAEWOO recommends that the coolant mix contain
50% commercially available automotive antifreeze, or
equivalent, and acceptable water to maintain an
adequate water pump cavitation temperature for efficient
water pump performance.
Premix coolant solution to provide protection to the
lowest expected outside (ambient) temperature. Pure
undiluted antifreeze will freeze at -23°C (-10°F).
Only use a greater concentration (above 50%) of
commercially available automotive antifreeze an needed
for anticipated outside (ambient) temperatures. Do not
exceed the recommendations, provided with the
commercially available automotive antifreeze, regarding
the coolant mixture of antifreeze to water.
G424 Service Manual
115
Cooling System
Belt Adjustment
V-Belt Diagnosis
Belts and pulleys wear evenly with use. Unusual signs
of wear indicate some correction is needed. The
correction of any of the listed conditions will help
extend belt life.
Drive belts must grip the entire contact area of the
pulley. When drive belts are too loose, the belts can
slip, tear, burn, or grab and snap. More belts fail from
being too loose than too tight.
Belts that are too tight can damage the engine by
causing side loading of the crankshaft, crankshaft
bearings, and accessories or accessory bearings. Too
much belt tension will also stretch and weaken the
belts.
Causes of Belt failure
•
•
•
•
•
•
•
•
After a belt has made one complete revolution it is
considered used and should be adjusted to the used
belt tension specification. When the drive belts are
worn, they should be replaced. Tightening worn drive
belts will not prevent slipping and can cause damage
to the engine.
Misalignment of the pulleys.
Wrong size belt.
Wrong length belt.
Wrong tension.
Damaged pulley sheaves or bent pulley shafts.
Damaged belt.
Belt damaged during installation.
Oil or grease on belts.
Base Cracking
Do not use belt dressings to extend belt life. Most
dressings contain chemicals that soften the belts.
Check the belts at 1500 hour intervals. Also check all
necessary mounting or adjusting bracket bolts.
A belt with excessive cross-checking that extends into
the rubber on the base of a belt and shows little or no
side wear indicates the belt is damaged. If the base of
the belt shows cross-checking, the belt has been
exposed to weather to the extent that the fabric is
starting to rot.
7 to 9 mm
(0.28 to 0.35 in.)
Fabric Tear
A fabric tear can be the result of:
• Operating a belt on a worn pulley.
• Belt tension too light causing the belt to ride in the
pulley groove.
• Dirty pulley grooves.
• Pulley misaligned.
Cover Tear
The fan belt is properly tense if it deflects 7 to 9mm
(0.28 to 0.35 in) as it is depressed with a finger
between the pulley and pulley of the long distance
side. Excessive tension can cause quick wear of the
belt and bearings of the water pump and the alternator
Excessive slackness ot presence of oil on the belt, on
the other hand, can lead to engine overheating and
insufficient charging due to slipping belt.
Cover tears result when the belts are too loose or too
long and the belt rubs against other compo-nents.
Adjust the belt tension and use the correct length of
belt.
Slip Burn
CATUTION : Never attempt to adjust tension of the fan
belt while leaving the engine in operation.
G424 Service Manual
Slip burns occur when the belts are too loose or
slipping under load. Install a new belt and adjust
properly. Check for a worn pulley.
116
Cooling System
Gouged Edge
Service Procedures
A gouged edge in a belt can be caused by a damaged
pulley, a misaligned pulley, or the belt being too loose
or too long. Check the pulley and the belt for proper
alignment and tension. Make sure other components
are not misaligned and rubbing against the belt.
Draining and Filling the Cooling
System
Various methods and equipment can be used.
Worn Sides
Draining
Belts that are worn on the sides are probably too
loose. The pulley may also be misaligned. Install a
new belt and adjust properly. Check for a worn or
misaligned pulley.
1. Place a drain pan under the radiator drain cock.
2. Install a tube on the drain cock.
3. Place the end of the tube in the pail or pan.
Excessive Stretch
4. Make sure the cooling system is cool, then remove
the radiator cap.
A belt that is stretched beyond adjustment is usually
the wrong size or is adjusted too tight.
Replace the belt and adjust the tension.
5. Open the drain cock completely.
6. Let the cooling system drain until the flow stops.
Flat Spots
7. Place a drain pan under the engine.
Flat spots may result by not relieving the belt tension
while storing the vehicle or engine. A temporary
vibration will occur when the engine is first started. Flat
spots are most noticeable with variable speed drives.
Flat spots may disappear during normal engine
operation. If the flat spots remain, replace the belts.
8. Remove the drain plug in the engine block.
9. Let the engine block drain until the flow stops.
There may be more drainage from the radiator at
this time.
10. Replace the engine block drain plug.
Internal Cord Damage
11. Close the drain cock.
Cords may be broken by prying the belt onto the pulley
or debris on the pulley. Internal cord damage will
cause the belt to roll out of the pulley groove.
Replace the belt and adjust properly.
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117
Cooling System
Filling
Radiator Service
1. Check the radiator drain cock to be sure it is closed.
Radiator Internal Deposits
2. Check the engine drain plug to be sure it is tight.
A radiator with a dirty, obstructed, or leaking core will
cause the engine to overheat. A scale deposit inside
the radiator is a result of using hard, high mineral
content water in the cooling system. The effect of heat
on the minerals in the water causes the formation of
scale, or hard coating, on metal surfaces within the
radiator, thereby reducing the transfer of heat. Some
hard water will produce a silt-like deposit which
restricts the flow of water. Replace a radiator that is
plugged or has a heavy scale on the core.
3. Premix the antifreeze with clear water in 50/50
mixture.
IMPORTANT: If the old coolant is to be re-used, check
it for glycol/water mix of 50/50.
4. Place a large top funnel in the radiator fill hole.
5. Slowly pour in the coolant. The filling may be
slowed because of the thermostat being closed.
Scale Removal
6. After the cooling system is filled to 1/2 inch below
the fill hole, start the engine and let the cooling
system warm up. When the thermostat opens, the
coolant level may drop. If the level drops, add
coolant until the level is up to the fill hole.
To remove the hardened scale, a direct chemical
action is necessary. A flushing compound at the
specified rate of 30 grams per liter (4 oz. per gallon) of
radiator capacity should be added to the coolant
solution in the form of a dissolved solution while the
engine is running. Operate the engine for 15 minutes
or until it reaches normal operating temper-ature, then
drain and flush the system with clean water.
7. Replace the radiator cap.
8. Check the coolant level in the recovery tank.
Add coolant if needed.
There are various types of flushing compounds
commercially available, but they should be obtained
from a reliable source. Most compounds attack metals
and should not remain in the engine for more than a
few minutes. A neutralizer should be used in the
cooling system immediately after a descaling solvent
is used. For extremely hard, stubborn coatings, such
as lime scale, use a stronger solution. The corrosive
action of a stronger solution will affect the thin metals
of the radiator, thereby reducing its operating life. A
complete flushing and rinsing is mandatory and must
be accomplished skillfully.
Flushing the Cooling System
Various methods and equipment can be used to flush
the cooling system. If special equipment such as a
back flusher is used, follow the equipment
manufacturer's instructions.
NOTICE
If the engine is damaged Internally and a new engine
assembly is installed in the vehicle, make sure all
foreign material is completely flushed out of the
cooling system. The oil cooler system should also be
flushed out (if equipped). Failure to rid the oil or
cooling system of debris can result in damage to the
replacement engine.
After the solvent and neutralizer have been used and
the cooling system is flushed, drain the entire system
and fill it with clean, soft water plus a high boiling type
antifreeze that meets GM 6038-M spec-ifications. After
filling the cooling system, check for radiator, hose, and
engine coolant leaks.
IMPORTANT: Remove the thermostat before flushing
the cooling system.
G424 Service Manual
118
Cooling System
Remove & Install Water
Temperature Sender
1
2
1. Disconnect one wire connection (1).
2. Remove water temperature sender (2).
NOTE: For the installation of the water temperature
sender, reverse the removal steps.
3. Use thread sealant on the water temperature
sender threads.
G424 Service Manual
119
Cooling System
BASE ENGINE SERVICE PROCEDURE
Timing Belt
Removal and Installation
A
B
C
H
G
G
G
F
E
D
G424 Service Manual
Removal steps
1. Timing belt front cover upper
2. Timing belt front cover lower
3. Timing belt
4. Tensioner spacer
5. Tensioner spring
6. Tensioner pulley
7. Oil pump sprocket
8. Crankshaft bolt
9. Crankshaft washer
10. Crankshaft sprocket
11. Flang
E
F
D
C
G
B
H
120
A
12. Tensioner B
13. Timing belt B
14. Counterbalance shaft sprocket
15. Spacer
16. Crankshaft sprocket B
17. Crankshaft key
18. Engine support bracket
19. Camshaft sprocket bolt
20. Camshaft sprocket
21. Timing belt rear cover
Base Engine Service Procedure
Removal Service Points
A
6EN0716
Timing belt removal
(1) When the timing belt is to be re-used, make an arrow
mark on the back surface on the belt to indicate the
rotating direction with a chalk or the like so that the belt
can be installed in the same direction.
(2) Move the timing belt tensioner upward and temporarily
tighten the tensioner lock bolt.
(3) Remove the timing belt.
6EN0884
B
Screw driver
Oil pump sprocket removal
(1) Remove the plug on the left side of cylinder block.
(2) Insert a screwdriver (shank diameter 8 mm[0.31 in.]) to
block the counterbalance shaft.
(3) Remove the nut.
(4) Remove the oil pump sprocket.
6EN0663
C
Crankshaft bolt removal
(1) Hold the flywheel with the special tool as shown.
(2) Remove the crankshaft bolt.
MD998781
6EN0868
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121
Base Engine Service Procedure
D
Crankshaft sprocket removal
MD998778
(1) If it is difficult to remove the sprocket, use the special tool.
6EN0642
E
Timing belt “B” removal
(1) Make a mark on the back of the timing belt indicating the
direction of rotation so it may be reassembled in the same
direction if it is to be reused.
NOTE: Water or oil on the belt shortens its life drastically, so
the removed timing belt, sprocket, and tensioner must be free
from oil and water. These parts should not be washed.
Replace part if seriously contaminated.
6EN1322
(2) If there is oil or water on each part check front case oil
seals, camshaft oil seal and water pump for leaks.
F
Counterbalance shaft sprocket removal
(1) Set the special tool as shown to prevent the
counterbalance shaft sprocket from turning together.
(2) Loosen the bolt and remove the sprocket.
MD998785
6EN0636
G
MD998778
Crankshaft sprocket “B” removal
(1) If it is difficult to remove the sprocket, use the special tool.
6EN0637
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122
Base Engine Service Procedure
H
MB990767
Crankshaft sprocket removal
(1) Using the special tool show in the illustration, lock the
camshaft sprocket in position.
(2) Loosen the camshaft sprocket bolt.
MD998719
6EN0668
Inspection
1. Timing Belt
Replace belt if any of the following conditions exist.
(1) Hardening of back rubber.
Back side is glossy without resilience and leaves no
indent when pressed with fingernail.
8EN0066
Cracks
Peeling
Cracks
(2)
(3)
(4)
(5)
Cracks
Cracks
Cracks
Cracks
on rubber back.
or peeling of canvas.
on tooth bottom.
on belt sides.
Cracks
Cracks
8EN0044
(6) Abnormal wear of belt sides.
NOTE: The sides are normal if they are sharp as if cut by a
knife.
Rounded edge
Abuormal wear
(Flutty strand)
8EN0067
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123
Base Engine Service Procedure
(7) Abnormal wear on teeth
Earlier stage:
Canvas worn (canvas fibers napped, rubber lost,
discolored whitish, and unclear canvas texture)
Latter stage:
Canvas lost, rubber exposed (tooth width thinner)
(8) Missing tooth
Rubber exposed
Tooth missing
8EN0068
Installation Service Points
A
Camshaft sprocket installation
(1) Using the special tools show in the illustration, lock the
camshaft sprocket in position.
(2) Tighten the camshaft sprocket bolt to the specified torque.
MB990767
MD998719
6EN0669
B
Engine support bracket installation
(1) Coat the bolts illustrated with sealant before tightening.
Specified sealant: 3MTM AAD Part No. 8762 or equivalent
6EN0739
C
MD998785
Counterbalance shaft sprocket installation
(1) Install the counterbalance shaft sprocket and screw the
bolt.
(2) Install special tool as shown in the illustration to lock the
counterbalance shaft.
(3) Tighten the bolt, and then remove the special tool.
6EN0636
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124
Base Engine Service Procedure
D
Timing
marks
(on fron
case)
timing
marks
Timing belt “B” installation
(1) Align timing mark on the crankshaft sprocket “B” and
counterbalance shaft sprocket with the marks on the front
case respectively.
(2) Install the timing belt “B” on the crankshaft sprocket “B”
and counterbalance shaft sprocket. There should be no
slack on the tension side.
DEN0602
(3) Make sure that the relationship between the tensioner
pulley center and the bolt center is as shown in the
illustration.
Tensioner “B”
Center of
tensioner
paller
Center of bolt
6EN0571
(4) Move the tensioner “B” in the direction of arrow while
lifting with a finger to give a sufficient tension to the
tension side of timing belt. In this condition, tighten bolt to
secure tensioner “B”. When the bolt is tightened, use care
to prevent shaft from turning together. If shaft is turned
together, belt will be over tensioned.
6EN0572
Timing
marks
(5) Check to ensure that timing marks on sprockets and front
case are in alignment.
(6) Press with index finger the center of span on the tension
side of timing belt “B”. The belt must deflect 5 to 7 mm.
[0.196 to 0.276 in].
Belt
deflection
timing
marks
6EN0573
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125
Base Engine Service Procedure
E
Crankshaft bolt installation
(1) Using the special tool, hold the flywheel.
(2) Install the crankshaft pulley in position.
MD998781
6EN0634
F
Oil pump sprocket installation
(1) Insert a phillips screwdriver (shank diameter 8 mm[0.31
in.] shaft) through the plug hole on the left side of the
cylinder block to the left counterbalance shaft.
(2) Install the oil pump sprocket.
(3) Apply a proper amount of engine oil to the bearing
surfaces of the nuts.
(4) Tighten the nuts to the specified torque.
Screw driver
6EN0564
G
Spring end
Tensioner
spring
Spring
end
Crankshaft bolt installation
(1) Hook the tensioner spring end to the water pump body
projection and tensioner bracket.
(2) Move the tensioner fully toward the water pump and
tighten the bolt and tensioner spacer.
Bolt
Water pump
Tensioner
6EN0555
H
Timing belt installation
(1) Align the timing mark on the camshaft sprocket with that
on the cylinder head.
Timing mark
6EN0670
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126
Base Engine Service Procedure
(2) Align the timing mark on the crankshaft sprocket with that
on the front case.
Timing mask
6EN0671
(3) Align the timing mark on the oil pump sprocket with its
mating mark.
Timing mark
6EN0672
Tensioner
spacer
6EN0015
Timing mark
(4) Install the timing belt on the crankshaft sprocket, oil pump
sprocket and camshaft sprocket in that order.
There should be no slack on the tension side.
(5) Apply a reverse direction (counterclockwise) force to the
camshaft sprocket to make the tension side of the belt
“tight”. In that state, recheck that all the timing marks are
in alignment.
(6) Loosen a turn or two the tensioner bolt and nut that were
temporarily tightened to hold the tensioner on the water
pump side. This gives tension to the belt by the action of
the tensioner spring.
(7) Rotate the crankshaft by the amount equivalent to two
camshaft sprocket teeth in the forward (clockwise)
direction. Since this step is intended for giving the timing
belt proper tension, do not attempt rotate the crankshaft
in the reverse (counterclockwise) direction or press the
belt to check the tension.
Two
teeth
Timing
mark
Timing
belt
G424 Service Manual
6EN0562
127
Base Engine Service Procedure
(8) Apply force to the tensioner in the direction shown by
arrow to make the belt engage completely with each
sprocket.
Tensioner
6EN0017
(9) Tighten the tensioner attaching bolt to the specified
torque.
(10) Tighten the tensioner spacer to the specified torque.
Tensioner
spacer
NOTE: If the nut is tightened first, the tensioner may also turn
together with the nut and loose tension of the belt may result.
Always tighten the bolt (at the bottom of the tensioner) first
and then tighten the nut (at the top of the tensioner).
Tensioner
6EN0015
(11) Hold the center of the tension side span of the timing
belt (between the camshaft and oil pump sprockets)
between your thumb and index finger as shown. Then,
make sure that the clearance between the belt back
surface and cover meets the standard value.
Standard value: 14 mm (0.55 in.)
14mm
(0.55in)
6EN0616
G424 Service Manual
128
Base Engine Service Procedure
Intake Manifold
Removal and Installation
6EN1894
Removal steps
1. Water outlet
2. Gasket
3. Thermostat
G424 Service Manual
4. Engine hanger
5. Intake manifold
6. Gasket
129
Base Engine Service Procedure
Exhaust Manifold and Water Pump
Gasoline/LPG Engine
Removal and Installation
6EN1895
Removal steps
1. Oil level gauge
2. Oil level gauge guide
3. O-ring
4. Heat protector A
5. Heat protector B
6. Engine hanger
G424 Service Manual
A
A
130
7. Exhaust manifold
8. Gasket
9. Water inlet pipe
10.O-ring
11. Water hose
12. Water pump
13. Gasket
Base Engine Service Procedure
A
O-ring and water pipe installation
Replace the water inlet pipe O-ring with a new one.
Apply water to the outer circumference of the O-ring for
easier insertion into the water pump and thermostat housing.
Caution:
1) Never apply engine oil or any other oil or grease to the Oring.
2) Fasten the water pipe after the thermostat housing has
been installed.
G424 Service Manual
131
Base Engine Service Procedure
LPG Engine (Low Emission Version)
Removal and Installation
T=4.5(32.5)[45]
Removal steps
1. Oil level gauge
2. Oil level gauge guide
3. O-ring
4. Heat protector A
5. Heat protector B
6. Oxygen sensor
7. Engine hanger
G424 Service Manual
A
A
132
8. Exhaust manifold
9. Gasket
10. Water inlet pipe
11.O-ring
12. Water hose
13. Water pump
14. Gasket
Base Engine Service Procedure
Rocker Arms And Camshaft
Removal and Installation
6EN1896
G
A
G424 Service Manual
Removal steps
1. Breather hose
2. P.C.V. hose
3. P.C.V. valve
4. Oil filler cap
5. Rocker cover
6. Gasket
7. Semi-circular packing
8. Rocker arms and rocker shafts
9. Rear bearing cap
10. Rear arm D
11. Spring
133
D
D
D
C
B
B
E
F
A
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
Bearing cap No. 4
Rocker arm C
Bearing cap No. 3
Bearing cap No. 2
Wave washer
Right rocker shaft
Left rocker shaft
Front bearing cap
Lash adjuster
Oil seal
Camshaft
Base Engine Service Procedure
Removal Service Points
MD998443
A
Rocker arm and rocker shaft removal
Caution:
If the lash adjuster is re-used, clean the lash adjuster.
6EN0569
(1) Fit the lash adjuster onto the rocker arm without allowing
diesel fuel to spill out. Fit. Special tool MD998443 to
prevent the lash adjuster coming free and falling to the
floor.
Inspection
1. Camshaft
Measure the cam height and if the limit is exceeded,
replace.
Standard value: 41.62 mm (1.6386 in.)
Limit: 41.12 mm (1.6189 in.)
9EN0058
2. Lash Adjuster
Caution:
•The lash adjusters are precision-engineered mechanisms.
Do not allow them to become contaminated by dirt or other
foreign substances.
•Do not attempt to disassemble the lash adjusters.
•Use only fresh diesel fuel to clean the lash adjusters
Cutside
cleaning
A
Inside
cleaning
Filling with
diesel fuel
B
C
(1) Prepare three containers and approximately five liters of
diesel fuel. Into each container, pour enough diesel fuel to
completely cover a lash adjuster when it is standing
upright. Then, perform the following steps with each lash
adjuster.
6EN1698
G424 Service Manual
134
Base Engine Service Procedure
(2) Place the lash adjuster in container A and clean its
outside surface.
NOTE: Use a nylon brush if deposits are hard to remove.
Diesel
fuel
6EN1699
(3) While gently pushing down the internal steel ball using
special tool MD998442, move the plunger through five to
ten strokes until it slides smoothly. In addition to
eliminating stiffness in the plunger, this operation will
remove dirty oil.
Caution: The steel ball spring is extremely weak, so the lash
adjuster’s functionality may be lost if the air bleed wire is
pushed in hard.
Diesel fuel
MD998442
6EN1808
NOTE: If the plunger remains stiff or the mechanism appears
otherwise abnormal, replace the lash adjuster.
(4) Remove the lash adjuster from the container. Then, push
down the steel ball gently and push the plunger to
eliminate diesel fuel from the pressure chamber.
MD998442
Diesel fuel
6EN1809
(5) Place the lash adjuster in container B. Then, gently push
down the internal steel ball using special tool MD998442
and move the plunger through five to ten strokes until it
slides smoothly. This operation will clean the lash
adjuster’s pressure chamber.
Caution: The steel ball spring is extremely weak, so the lash
adjuster’s functionality may be lost if the air bleed wire is
pushed in hard.
Diesel fuel
6EN1808
G424 Service Manual
135
Base Engine Service Procedure
(6) Remove the lash adjuster from the container. Then, push
down the steel ball gently and push the plunger to
eliminate diesel fuel from the pressure chamber.
MD998442
Diesel fuel
6EN1809
(7) Place the lash adjuster in container C. Then, gently push
down the internal steel ball using special tool MD998442.
Caution: Do not use container C for cleaning. If cleaning is
performed in container C, foreign matter could enter the
pressure chamber when the chamber is filled with diesel fuel.
Diesel fuel
6EN1810
(8) Stand the lash adjuster with its plunger at the top, then
push the plunger downward firmly until it moves through
its greatest possible stroke. Return the plunger slowly,
then release the steel ball and allow the pressure
chamber to fill with diesel fuel.
Diesel fuel
6EN1811
(9) Remove the lash adjuster from the container, then stand
the lash adjuster with its plunger at the top.
Push the plunger firmly and check that it does not move.
NOTE: If lash adjuster contracts, perform the operations (7)
through (9) again to fill it with diesel fuel completely.
Replace the lash adjuster if it still contracts after performing
these steps.
6EN1704
G424 Service Manual
(10) Stand the lash adjuster upright to prevent diesel fuel
spilling out. Do not allow the lash adjuster to become
contaminated by dirt or other foreign matter. Fit the lash
adjuster onto the engine as soon as possible.
136
Base Engine Service Procedure
Installation Service Points
A
Camshaft installation
Apply engine oil to the journals and cams of the camshafts.
Install the camshaft on the cylinder head.
B
Notch
Rocker shaft installation
Insert the rocker shafts into the front bearing cap so that the
notches on the shafts face up, and insert the installation bolts
without tightening them.
Frout bearing cap
6EN0575
C
Wave washer
Wave washer installation
Install the wave washer in correct direction as shown.
Front
bearing
cap
No.1 intake
side rocker
arm
6EN0576
D
Rocker cover
Mounting bolt hole
Bearing cap
(1) No.3 bearing cap looks very similar to No.2 and No.4
bearing caps.
NOTE: No.2 bearing cap is the same as No.4 bearing cap.
Front mark
No.2
Indentification
No.3
G424 Service Manual
Mark
No.4
(2) Install the bearing caps with their front marks pointing to
the camshaft sprocket side.
6EN0024
137
Base Engine Service Procedure
E
MD998443
Lash adjuster installation
Caution: If the lash adjuster is re-used, clean the lash
adjuster.
(1) Set special tool MD998443 to prevent the lash adjuster
coming free and falling to the floor.
6EN0569
F
Camshaft oil seal installation
(1) Apply engine oil to the lip area of the oil seal and the
camshaft front end outer diameter.
(2) Using special tool, install the camshaft oil seal.
MD998713
6EN0650
G
Apply sealant
Semi-circular packing installation
(1) Apply sealant to the location shown in the illustration.
Specified sealant: 3MTM AAD Part No. 8672 or equivalent.
DEN0053
G424 Service Manual
138
Base Engine Service Procedure
Cylinder Head And Valves
Removal and Installation
6EN1897
A
B
D
C
B
B
C
B
G424 Service Manual
Removal steps
1. Cylinder head bolt
2. Cylinder head assembly
3. Cylinder head gasket
4. Retainer lock
5. Valve spring retainer
6. Valve spring
7. Intake valve
8. Retainer lock
9. Valve spring retainer
10. Valve spring
139
C
A
C
A
11. Exhaust valve
12. Valve stem seal
13. Valve spring seat
14. Valve stem seal
15. Valve spring seat
16. Intake valve guide
17. Exhaust valve guide
18. Intake valve seat
19. Exhaust valve seat
20. Cylinder head
Base Engine Service Procedure
Removal Service Points
A
MB991654
Cylinder head bolt removal
Using special tool, loosen the cylinder head bolts.
Loosen each bolt evenly, little by little, by two or three steps.
6EN0717
B
MD998772
Retainer lock removal
Store removed valves, springs and other parts, tagged to
indicate their cylinder No. and location for reassembly.
6EN0652
C
Valve stem seal removal
Caution: Do not reuse removed valve stem seal.
Inspection
1. Cylinder Head
6EN0718
6EN0719
G424 Service Manual
(1) Check the cylinder head for water leaks, gas leaks,
damage or cracks before cleaning.
(2) Thoroughly remove oil, water scale, sealant, carbon
deposit, etc. After the oil passages have been cleaned,
blow air to make sure that they are clean.
(3) Check the cylinder head gasket surface for flatness by
using straightedge and thickness gauge.
If the service limit is exceeded, correct to meet the
specification.
Standard valve: 0.03 mm (0.0012 in.) or less.
Limit: 0.2 mm (0.008 in.)
Grinding limit: 0.2 mm (0.008 in.)
Cylinder head height (when new): 89.9 to 90.1 mm
(3.539 to 3.547 in.)
NOTE: Grinding the cylinder head is permitted as long as the
total thickness of the metal removed from the cylinder head
and the cylinder block does not exceed 0.2 mm (0.008 in.).
140
Base Engine Service Procedure
2. Valve
Valve seat
contact
Margin
6EN0542
(1) Check the valve face for correct contact. If incorrect,
reface. Valve seat contact should be maintained uniform
at the center of valve face.
(2) If the margin exceeds the service limit, replace the valve:
Standard value:
Intake 1.2 mm (0.047 in.)
Exhaust 2.0 mm (0.079 in.)
Limit:
Intake 0.7 mm (0.028 in.)
Exhaust 1.5 mm (0.059 in.)
(3) Measure the valve’s total length. If the measurement is
less than specified, replace the valve.
Standard value:
Intake 106.6 mm (4.197 in.)
Exhaust 105.2 mm (4.142 in.)
Limit:
Intake 106.1 mm (4.177 in.)
Exhaust 104.7 mm (4.122 in.)
3. Valve Spring
Out of squareness
Free height
1EN0264
(1) Measure the free height of spring and, if it is smaller than
the limit, replace.
Standard value: 48.0 mm (1.89 in.)
Limit: 47.0 mm (1.85 in.)
(2) Measure the squareness of the spring and, if the limit is
exceeded, replace.
Standard value: 2 degrees or less
Limit: 4 degrees
4. Valve Guide
Measure the clearance between the valve guide and valve
stem. If the limit is exceeded, replace the valve guide or
valve, or both.
Valve
guide
Guide I.D.
Stem I.D.
G424 Service Manual
1EN0279
141
Base Engine Service Procedure
Valve stem end
Valve Projection
Spring seating
surface
5. Valve Seats
(1) Assemble the valve, than measure the valve stem
projection between the end of the valve stem and the
spring seating surface. If the measurement exceeds the
specified limit, replace the valve seat.
Standard value: 42.05 mm (1.6555 in.)
Limit: 42.55 mm (1.6752 in.)
DEN0212
0.9
(0.0 to 1.3
35 t
o 0.
05
Unit : mm(in)
1)
60˚
Valve Seat Reconditioning Procedure
)
o 1.3 .051
0.9 0t 35 to 0
(0.
60˚
25˚
43.5˚ to 44˚
(1) Before correcting the valve seat, check for clearance
between the valve guide and valve and, if necessary,
replace the valve guide.
(2) Correct to obtain the specified seat width and angle.
(3) After correction, valve and valve seat should be lapped
with a lapping compound.
43.5˚ to
44˚
25˚
1EN0105
0.5 to 1.0
Unit : mm(in)
(0.020 to 0.039)
Valve Seat Replacement Procedure
(1) Cut the valve seat to be replaced from the inside to thin
the wall thickness. Then, remove the valve seat.
Cut away
0.5 to 1.0
(0.020 to 0.030)
1EN0274
(2) Rebore the valve seat hole in the cylinder head to a
selected oversize valve seat diameter.
(3) Before fitting the valve seat, cool the valve seat in liquid
nitrogen, to prevent the cylinder head bore from galling.
(4) Using a valve seat cutter, correct the valve seat to the
specified width and angle.
See “Valve Seat Reconditioning Procedure”.
Height of
valve seat
Over size I.D
1EN0275
G424 Service Manual
142
Base Engine Service Procedure
Valve Guide Replacement Procedure
(1) Using a press, remove the valve guide toward the cylinder
block side.
(2) Rebore the valve guide hole to the new oversize valve
guide outside diameter.
NOTE: Do not install a valve guide of the same size again.
Valve guide hole diameter.
0.05 O.S. 13.05 to 13.07 mm (0.5138 to 0.5146 in.)
0.25 O.S. 13.25 to 13.27 mm (0.5217 to 0.5224 in.)
0.50 O.S. 13.50 to 13.52 mm (0.5315 to 0.5323 in.)
Press
(3) Press in the valve guide to the position shown in the
illustration.
Standard value: 11.5 mm (0.453 in.)
Press
11.5mm
(0.453 in)
Push rod
Valve
guide
Removal
Valve
guide
Installation
6EN0543
NOTE:
1) Press-fit the valve guide, working from the cylinder head
top surface.
2) Note that the intake and exhaust side valve guides are
different in length.
3) After installing valve guides, insert new valves in them to
check for sliding condition.
Installation Service Points
MD998729
A
Valve stem seal installation
(1) Install the valve spring seat.
(2) Using special tool, install the new valve stem seat to the
valve guide.
6EN0743
Caution:
1) Do not reuse removed valve stem seal.
2) The special tool must be used to install the valve stem
seal. Improper installation could result in oil leaking past
the valve guide.
B
Indentification
color
Spring
retainer
Valve spring installation
Direct the valve spring end with identification color toward the
rocker arm.
Stem seal
Spring seat
6EN0437
G424 Service Manual
143
Base Engine Service Procedure
C
MD998772
Retainer lock installation
The valve spring, if excessively compressed, causes the
bottom end of the retainer to be in contact.
6EN0652
D
Cylinder head bolt installation
(1) When installing the cylinder head bolts, check that the
shank length of each bolt meets the limit is exceeded,
replace the bolt.
Standard value: 120.4 mm (4.740 in.)
(2) Apply engine oil to the bolt threads and washers.
Shank length
6EN0782
8
10
6
4
1
2
3
5
9
7
6EN0694
G424 Service Manual
(3) According to the tightening sequence, tighten the bolts to
8.0 kg•m (57.9 lb•ft)[80 N•m].
(4) Loosen the bolts completely.
(5) Torque the bolts to 2.0 kg•m (14.5 lb•ft)[20 N•m].
(6) Tighten the bolts 1/4 turns (90°) more.
(7) Tighten the bolts 1/4 turns (90°) additionally.
Caution:
1) If the bolt is turned less than 90°, proper fastening
performance may not be expected. When tightening the
bolt, therefore, be careful to give a sufficient turn to it.
2) If the bolt is over tightened, loosen the bolt completely and
then retighten it by repeating the tightening procedure
from step (1).
144
Base Engine Service Procedure
Front Case And Oil Pan
Removal and Installation
6EN1898
N
M
A
L
K
B
J
C
I
G424 Service Manual
Removal steps
1. Oil filter
2. Oil pressure switch
3. Drain plug
4. Drain plug gasket
5. Oil pan
6. Oil screen
7. Oil screen gasket
8. Plug
9. O-ring
10. Flange bolt
11. Relief plug
12. Gasket
13. Relief spring
14. Relief plunger
15. Oil filter bracket
16. Oil filter bracket gasket
H
G
G
G
F
E
D
D
E
E
145
C
B
A
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
Oil pump case assembly
Front case gasket
Oil pump cover
Oil pump drive gear
Oil pump driven gear
Crankshaft front oil seal
Oil pump oil seal
Counterbalance shaft oil seal
Front case
Counterbalance shaft, left
Counterbalance shaft, right
Counterbalance shaft, front bearing
Counterbalance shaft, rear bearing,left
Counterbalance shaft, rear bearing, right
Base Engine Service Procedure
Removal Service Points
MD998727
A
Oil pan removal
(1) Remove the all oil pan bolts.
(2) Drive in the special tool between the cylinder block and
oil pan
(3) Side the tool by striking the edge of the special tool to
separate the oil pan from the cylinder block.
6EN0698
B
MD998162
Plug removal
(1) Fit special tool MD998162 on the plug, then hold it in
position with special tool MD998783.
(2) Loose the plug.
MD998783
6EN0909
C
Oil pump oil seal installation
(1) Remove the plug on the side of cylinder block.
(2) Insert a phillips screwdriver(shank diameter 8mm[0.31
in.]) into the plug hole to lock the counterbalance shaft.
Screw driver
Plug
6EN1026
(3) Loosen the flange bolt.
6EN0565
G424 Service Manual
146
Base Engine Service Procedure
D
Counterbalance shaft front bearing removal
(1) Using the special tool, remove the counterbalance shaft
front bearing from the cylinder block.
NOTE: Be sure to remove the front bearing first. If it has not
been removed, the rear bearing puller cannot be used.
MD998371
Front
bearing
3EN0166
E
Counterbalance shaft rear bearing removal
MB991603
(1) Using the special tool, remove the counterbalance shaft
rear bearing from the cylinder block.
NOTE: When removing the left counterbalance shaft
bearing, install the special tool (MB991603) in front of the
cylinder block.
MD998372
6EM0207
Inspection
1. Front Case
(1) Check oil holes for clogging and clean if necessary.
(2) Check the left counterbalance shaft front bearing section
for wear, damage and seizure. If there is anything wrong
with the section, replace the front case.
(3) Check the front case for cracks and other damage.
Replace cracked or damaged front case.
2. Oil Seal
(1) Check the oil seal lip for wear and Replace oil seal if
necessary.
(2) Check the oil seal lip for deterioration. Replace oil seal if
necessary.
3. Counterbalance Shaft
(1) Check oil hole for clogging.
(2) Check journals for seizure, damaged and contact with
bearing. If there is anything wrong with the journal
assembly.
DEN0711
G424 Service Manual
147
Base Engine Service Procedure
4. Oil Pump
6LU0013
(1) Assemble the oil pump to the front case and rotate it to
ensure smooth rotation with no looseness.
(2) Check the side clearance using a thickness gauge.
(3) Check the side clearance
Standard value:
0.08 to 0.14 mm (0.0031 to 0.0055 in.)
Drive gear
0.06 to 0.12 mm (0.0024 to 0.0047 in.)
Driven gear
Installation Service Points
A
Right counterbalance shaft rear bearing
installation
(1) Apply engine oil to the outer surface of bearing.
(2) Using special tools, install right rear bearing. Make sure
that oil hole of bearing is aligned with oil hole of cylinder
block.
MD998705
MD998705
Cylinder block
6EN1034
G424 Service Manual
148
Base Engine Service Procedure
B
MB991603
Left counterbalance shaft rear bearing
installation
(1) Install the special tool (Guide Plate) to cylinder block.
(2) Apply engine oil to the rear bearing outer circumference
and bearing hole in the cylinder block.
(3) Using the special tool, install the rear bearing.
NOTE: The left rear bearing has no oil holes.
MD998705
6EN0208
Rear bearing
MB991603
MD998705
6EN0557
C
Counterbalance shaft front bearing installation
(1) Using the special tool, install the rear bearing.
MD998705
MD998705
Bearing
Cylinder block
6EN1035
G424 Service Manual
149
Base Engine Service Procedure
D
Socket wrench
Oil seal
Counterbalance shaft oil seal installation
(1) Using a suitable socket wrench, install the
counterbalance shaft oil into the front case.
Front case
6EN0580
E
Oil pump oil seal installation
(1) Using a suitable socket wrench, install the oil pump oil
seal into the front case.
Socket
Oil seal
Front case
6EN0494
F
MD998375
Crank shaft front oil seal installation
(1) Using the special tool, install the crankshaft front oil seal
into the front case.
Oil seal
Front case
6EN0579
G
Alignment
mark
Oil pump driven gear/oil pump drive gear
installation
(1) Apply engine oil amply to the gears and line up the
alignment marks.
6LU0015
G424 Service Manual
150
Base Engine Service Procedure
H
Front case installation
(1) Set the special tool on the front end of the crankshaft
and apply a thin coat of engine oil to the outer
circumference of the special tool to install the front case.
MD998285
6EN0746
(2) Install the front case assembly through a new front case
gasket and temporarily tighten the flange bolts(other
than those for tightening the filter bracket).
MD998285
6EN0747
I
Flange bolt installation
(1) Insert a Phillips screwdriver into a hole in the left side of
the cylinder block to lock the counterbalance shaft.
Screw driver
6EN0564
(2) Secure the oil pump driven gear onto the left
counterbalance shaft by tightening the flange bolt to
specified torque.
6EN0565
G424 Service Manual
151
Base Engine Service Procedure
J
MD998162
Plug installation
(1) Install a new o-ring to the groove of the front case.
(2) Install a plug to the front case.
(3) Fit the special tool MD998162 on the plug, and then
hold in position with special tool MD998783.
(4) Tighten the plug to the special tool MD998783.
(5) Remove the special tools MD998783 and MD998162.
MD998783
6EN0909
K
FIPG
Oil pan installation
(1) Clean both mating surface of the oil pan and cylinder
block.
(2) Apply a 4 mm (0.16 in.) wide bead of FIPG to the entire
circumference of the oil pan flange. The oil pan should
be installed in 15 minutes after the application of FIPG.
Specified FIPG: 3MTM AAD Part No.8672 or equivalent
Groove
portion
Bolt hole
portion
6EN0213
(3) Note the difference in bolt lengths at the location shown.
Crank pulley side
8mm bolts
Oil pan viewed from lower side
6EN0449
Drain plug
L
Drain plug gasket installation
(1) Install the drain plug gasket in the direction shown.
Caution: Fitting the gasket in a wrong way will result in oil
leakage.
Oil seal
Gasket
Oil pan side
7EN0179
G424 Service Manual
152
Base Engine Service Procedure
M
Oil pressure switch installation
Specified sealant: 3MTM AAD Part No. 8672 or equivalent
Sealant
Caution:
1) Keep the end of threaded portion clear of sealant.
2) Avoid an over tightening.
9EN0094
N
Bracket side
Engine Oil
Oil filter installation
(1) Clean the installation surfaces of the filter bracket.
(2) Apply engine oil to the o-ring of oil filter.
(3) Screw the oil filter in until the o-ring contacts the
bracket.
6EN0591
G424 Service Manual
153
Base Engine Service Procedure
Piston And Connecting Rod
Removal and Installation
6EN1899
A
G
F
E
D
E
C
G424 Service Manual
Removal steps
1. Nut
2. Connecting rod cap
3. Connecting rod bearing
4. Piston and connecting rod assembly
5. Connecting rod bearing
6. Piston ring No. 1
154
B
C
B
A
7. Piston ring No. 2
8. Oil ring
9. Piston pin
10. Piston
11. Connecting rod
12. Bolt
Base Engine Service Procedure
Removal Service Points
A
Cylinder
number
Connecting rod cap removal
Mark the cylinder number on the side of the connecting rod
big end for correct reassembly.
DEN0050
unit:mm(in)
Push rod
Guide B
Guide C
Base
Guide A
17.9(0.705)
B
Piston pin removal
The special tool, Piston Pin Setting Tool (MD998780),
consists of the parts shown in the illustration at the left.
Guide A
18.9(0.744)
Guide A
20.9(0.823)
Guide A
21.9(0.862)
7EN0431
Push rod
Front mark
Front
mark
(1) Insert the special tool, Push Rod, into the piston from
the side on which the front mark is stamped in the piston
head, and attach the guide C to the push rod end.
(2) Place the piston and connecting rod assembly on the
special tool, Piston Pin Setting Base, with the front mark
facing upward.
(3) Using a press, remove the piston pin.
NOTE: Keep the disassembled piston, piston pins and
connecting rods in order according to the cylinder number.
Guide C
Base
7EN0390
G424 Service Manual
155
Base Engine Service Procedure
Inspection
1. Piston Ring
7EN0475
Press down ring
with piston
Piston ring
End gap
(1) Check for the clearance between the piston ring and ring
groove. If the limit is exceeded, replace the ring or both
piston and ring.
(2) Install the piston ring into the cylinder bore. Force it
down with a piston, its crown being in contact with the
ring, to correctly position it at right angles to the cylinder
wall. Then, measure the end gap with a feeler gauge.
If the ring gap is excessive, replace the piston ring.
Standard value:
No.1 0.25 to 0.40 mm (0.0098 to 0.0157 in.)
No.2 0.45 to 0.60 mm (0.0177 to 0.0236 in.)
Oil
0.20 to 0.60 mm (0.0079 to 0.0236 in.)
Limit:
No.1, No.2
0.8 mm(0.031 in.)
Oil
1.0 mm (0.039 in.)
7EN0476
2. Crankshaft Pin Oil Clearance (Plastic Gauge
Method)
1EN0246
G424 Service Manual
(1) Remove oil from the crankshaft pin and the connecting
rod bearing.
(2) Cut the plastic gauge to the same length as the width of
the bearing and place it on the crankshaft pin in parallel
with its axis.
(3) Install the connecting rod cap carefully and tighten the
bolts to the specified torque.
(4) Remove the bolt and carefully remove the connecting
rod cap.
(5) Measure the width of the plastic gauge at its widest part
by using the scale printed on the plastic gauge package.
Standard value: 0.02 to 0.05 mm (0.0008 to 0.0020 in.)
Limit: 0.1 mm (0.004 in.)
156
Base Engine Service Procedure
Piston
Installation Service Points
A
Connecting rod
Piston pin
A7EN0432
Piston pin installation
(1) Measure the following dimensions of the piston, piston
pin and connecting rod.
A: Piston pin insertion hole length
B: Distance between piston bosses
C: Piston pin length
D: Connecting rod
(2) Obtain dimension L (to be used later) from the above
measurements by using by following formula.
(A - C) - (B - D)
L=
2
(3) Insert the special tool, Push Rod, into the piston pin and
attach the guide A to the push rod end.
(4) Assemble the connecting rod in the piston with their front
marks facing the same direction.
(5) Apply engine oil to the entire periphery of the piston pin.
(6) Insert the piston pin, push rod and guide A assembly
having assembled in stop (3) from the guide A side into
the piston pin hole on the front marked side.
(7) Screw the guide B into the guide A until the gap between
both guides amounts to the value L obtained in step (2)
plus 3 mm (0.12 in.)
3mm (0.12in) +L2
Guide B
Guide A
7EN0433
Push rod
Piston pin
Front mark
Front mark
(8) Place the piston onto the piston setting base with the
front marks directed upward.
(9) Press-fit the piston pin using a press.
If the press-fitting force required is less than the
standard value, replace the piston and piston pin set
or/and the connecting rod.
Standard value: 750 to 1750 kgf
(1654 to 3859 lbf)
[7350 to 17160 N]
Guide A
Base
Guide B
7EN0391
G424 Service Manual
157
Base Engine Service Procedure
B
Side
rail
Oil ring installation
(1) Fit the oil ring spacer into the piston ring groove. First,
install the upper side rail, and then install the lower side
rail.
Spacer
6EN0585
NOTE:
1) The side rails and spacer may be installed in either
direction.
2) The new spacers and side rails are painted in the
following colors to identify their sizes.
Size
Identification color
STD
No color
0.50 mm (0.020 in.) O.S.
Blue
1.00 mm (0.040 in.) O.S.
Yellow
(2) To install the side rail, first fit one end of the rail into the
piston groove, then press the remaining portion into
position by finger. See illustration.
Side rail gap
Caution: The side rail could be broken if it is expanded with
a piston ring expander in the same way as with a
compression ring.
(3) Make sure that the side rails move smoothly in either
direction.
7EN0451
Identification
Identification
Size mark
mark
C
Piston ring No.2/piston ring No.1 installation
(1) To prevent wrong installation, check the identification
mark of each piston ring. The installation mark is
stamped near the ring gap.
NOTE: Size mark on piston ring are as follows.
9EN0524
G424 Service Manual
Size
Size mark
STD
Paint red
0.50 mm (0.020 in.) O.S.
50
1.00 mm (0.040 in.) O.S.
100
158
Base Engine Service Procedure
(2) Using piston ring expander, fit No.2 and then No.1 piston
ring into position.
NOTE: Install piston ring with identification mark facing up,
to the piston crown
(3) Install the No.1 piston ring in the same manner as
step 2.
7EN0452
D
Upper
side
rail
No.1
Piston pin
No.2 ring gap
and space gap
Lower side
ral
6EN0549
Piston and connecting rod installation
(1) Liberally coat engine oil on the circumference of the
piston, piston ring, and oil ring.
(2) Arrange the piston ring and oil ring gaps (side rail and
spacer) as shown in the illustration.
(3) Insert the piston and connecting rod assembly from
above the cylinder in such a way that the front
mark(arrow) on the top of the piston will be directed
toward the camshaft sprocket.
(4) Insert the piston and connecting rod assembly with the
piston rings held firmly with a ring band. Forcing it by
pounding should be avoided because damage to the
piston rings or crank pin could result.
9EN0072
G424 Service Manual
159
Base Engine Service Procedure
E
No.1
No.4
Connecting rod bearing installation
When the bearings are replaced, select and install them
according to the identification colors on the crankshaft and
identification marks stamped on the connecting rod bearing.
Crankshaft
Pin
No.2
No.3
6EN0700
Pin O.D.
Identification
Thickness,
identification mm (in.)
mark or color
mm (in.)
color
Yellow
44.995 to
45.000
(1.77145 to
1.77165)
1
or Yellow
None
44.985 to
44.995
(1.77106 to
1.77145)
2
or None
White
44.980 to
44.985
(1.77086 to
1.77106)
3
or Blue
Identfication mark
6AE0115
1.487 to
1.491
(0.05854 to
0.05870)
1.491 to
1.495
(0.05870 to
0.05886)
1.495 to
1.499
(0.05886 to
0.05902)
Connecting rod inside diameter:
48.000 to 48.015 mm (1.88976 to 1.89035 in.)
F
Cylinder No.
Connecting rod bearing
Connecting rod cap installation
(1) Verifying the mark made during disassembly, install the
bearing cap to the connecting rod. If the connecting rod
is new with no index mark, make sure that the bearing
locking notches come on the same side as shown.
Notches
DEN0051
(2) Make sure that connecting rod big end side clearance
meets the specification.
Standard value: 0.10 to 0.25 mm (0.0039 to 0.0098 in.)
Limit: 0.4 mm (0.016 in.)
6EN0621
G424 Service Manual
160
Base Engine Service Procedure
G
Connecting rod cap nut installation
(1) Since the connecting rod bolts and nuts are torque using
a plastic area tightening method, they should be
examined BEFORE reuse. If the bolt threads are
“necked down”, the bolts should be replaced.
Necking can be checked by running a nut with fingers to
the full length of the bolt’s thread. If the nut does not run
down smoothly, the bolt should replaced.
(2) Before installing the nuts, the threads should be oiled
with engine oil.
(3) Install both nuts on the bolts finger tight, then alternately
torque each nut to assemble the cap properly.
(4) Tighten the nuts to 2.0 kg•m (14.5 lb•ft) [20 N•m] and
plus 1/4 (90°) turn.
Caution:
1) If the nut is turned less than 90°, proper fastening
performance may not be expected. When tightening the
nut, therefore, be careful to give a sufficient turn to it.
2) If the nut is over tightened (exceeding 100°), loosen the
nut completely and then retighten it by repeating the
tightening procedure from step (1).
G424 Service Manual
161
Base Engine Service Procedure
Crankshaft And Cylinder Block
Removal and Installation
6EN1900
F
E
D
C
G424 Service Manual
Removal steps
1. Flywheel bolt
2. Flywheel
3. F/W Housing
4. Cover - F/W Housing
5. Oil seal case
6. Oil seal
7. Crankshaft bearing cap bolt
C
B
B
B
162
8. Crankshaft bearing cap
9. Crankshaft bearing lower
10. Crankshaft
11. Crankshaft bearing upper
12. Thrust bearing
13. Cylinder block
Base Engine Service Procedure
Inspection
Plastic gauge
1. Crankshaft Oil Clearance (Plastic Gauge
Method)
Use of the plastic gauge can facilitate the oil clearance
measurement work.
To use the plastic gauge, proceed as follows:
(1) Remove oil from the crankshaft journal and crankshaft
bearing.
6EN0703
(2) Install the crankshaft.
(3) Cut the plastic gauge to the same length as the width of
the bearing and place it on the journal in parallel with its
axis.
(4) Install the crankshaft bearing cap carefully and tighten
the bolts to specified torque.
(5) Remove the bolt, and carefully remove the crankshaft
bearing cap.
(6) Measure the width of the plastic gauge at its widest part
by using a scale printed on the plastic gauge package.
Standard value: 0.02 to 0.04 mm (0.0008 to 0.0016 in.)
Limit: 0.1 mm (0.004 in.)
6EN0623
2. Cylinder Block
(1) Visually check for scratches, rust, and corrosion. Use
also a flaw detecting agent for the check. If defects are
evident, correct, or replace.
(2) Using a straightedge and feeler gauge, check the block
top surface for warpage. Make sure that the surface is
free from gasket chips and other foreign matter.
Standard value: 0.05 mm (0.0020 in.)
Limit: 0.1 mm (0.004 in.)
9EN0074
6EN0553
G424 Service Manual
(3) Check the cylinder walls for scratches and seizure. If
defects are evident, correct (bored to oversize) or
replace.
(4) Using a cylinder gauge, measure the cylinder bore and
cylindricity. If worn badly, rebore all cylinders to an
oversize and replace piston rings. Measure at the points
shown in the illustration.
Standard value:
Cylinder I.D.
86.50 to 86.53 mm (3.4055 to 3.4067 in.)
Cylindricity 0.1 mm (0.004 in.)
163
Base Engine Service Procedure
3. Cylinder Boring
Thrust
direction
Piston O.D
6En0554
(1) Oversize pistons to be used should be determined on
the basis of largest bore cylinder.
(2) Oversize pistons are available in four size 0.50 mm
(0.0197 in.), and 1.00 mm (0.0394 in.). Rebore the
cylinder to a diameter that matches the selected piston
outside diameter that matches the selected piston
outside diameter with the specified clearance. The
reference piston outside diameter measuring point is
shown in the illustration.
(3) Based on the measured piston O.D. calculate the boring
finish dimension.
Boring finish dimension = Piston O.D. + 0.02 to 0.04 mm
(0.0008 to 0.0016 in.) (clearance between piston O.D.
and cylinder ) - 0.02 mm (0.0008 in.) (honing margin)
(4) Bore all cylinders to the calculated boring finish
dimension.
Caution: To prevent distortion that may result from
temperature rise during boring, bore cylinders, working from
No.2 to No.4 to No.1 to No.3.
(5) Hone to the final finish dimension (piston O.D. +
clearance between piston O.D. and cylinder).
(6) Check the clearance between the piston and cylinder.
Standard value:
Clearance between piston and cylinder
0.02 to 0.04 mm (0.0008 to 0.0016 in.)
Installation Service Points
A
Crankshaft thrust bearing installation
(1) Install the two thrust bearing in the No.3 bearing bore in
the cylinder block. For easier installation, apply engine
oil to the bearings, this will help fold them in position.
(2) The thrust bearings must be installed with their groove
side toward the crankshaft web.
Groovers
6EN1557
G424 Service Manual
164
Base Engine Service Procedure
B
Crankshaft bearing installation
(1) From the following table, select a bearing whose size is
appropriate for the crankshaft journal outside diameter.
Crankshaft journal
outside diameter
Cylinder
Crankshaft
block bearing bearing for
No.3
bore
Identification
mark or
color
Identification
Size
Identification Identification Identification
color
mm (in.)
mark
Yellow
56.994 to
57.000
(2.2439 to
2.2241)
None
White
56.988 to
56.994
(2.2436 to
2.2439)
56.982 to
56.988
(2.2434 to
2.2436)
mark or color mark or color
0
1 or Green 0 or Black
1
2 or Yellow 1 or Green
2
3 or None 2 or Yellow
0
2 or Yellow 1 or Green
1
3 or None 2 or Yellow
2
4 or Blue
0
3 or None 2 or Yellow
1
4 or Blue
3 or None
2
5 or Red
4 or Blue
3 or None
6EN0705
If the crankshaft journal outside diameter ID color is “yellow”
and the cylinder block bearing bore ID mark is “1” for
example, select a bearing whose ID mark is “2” or ID color is
“yellow” for No. 1, 2, 4 and 5, and a bearing whose ID mark
is “1” or ID color is “green” for No. 3.
Bearing bore
identification
mark
If there is no ID color paint on the crankshaft, measure the
journal outside diameter and select a bearing appropriate for
the measured value.
Cylinder
inner
diameter
size mark
Bottom of
cylinder block
Rear face of
cylinder block
6EN1632
G424 Service Manual
165
Base Engine Service Procedure
Crankshaft journal
Identification
color
Cylinder block bearing support section
O.D. mm (in.)
Yellow
Crankshaft bearing
Identification
mark
I.D. mm (in.)
Identification
mark
Thickness mm(in.)
0
61.000 to 61.006
1
1.988 to 1.991
(2.40157 to 2.40181)
56.994 to 57.000
1
(2.24385 to 2.24409)
61.006 to 61.012
(0.07827 to 0.07839)
2
(2.40181 to 2.40204)
2
61.012 to 61.018
(0.07839 to 0.07850)
3
(2.40204 to 2.40228)
None
0
61.000 to 61.006
1
(2.24362 to 2.24189)
61.006 to 61.012
2
61.012 to 61.018
3
0
61.000 to 61.006
4
1
(2.24338 to 2.24362)
61.006 to 61.012
3
61.012 to 61.018
(2.40204 to 2.40228)
1.994 to 1.997
(0.07850 to 0.07862)
4
(2.40181 to 2.40204)
2
1.997 to 2.000
(0.07862 to 0.07874)
(2.40157 to 2.40181)
56.982 to 56.988
1.994 to 1.997
(0.07850 to 0.07862)
(2.40204 to 2.40228)
White
1.991 to 1.994
(0.07839 to 0.07850)
(2.40181 to 2.40204)
2
1.994 to 1.997
(0.07850 to 0.07862)
(2.40157 to 2.40181)
56.988 to 56.944
1.991 to 1.994
1.997 to 2.000
(0.07862 to 0.07874)
5
2.000 to 2.003
(0.07874 to 0.07886)
Identification mark of
color
6EN1096
Groove
(2) Install the bearing having an oil groove to the cylinder
block.
(3) Install the bearing having no oil groove to the bearing
caps.
for upper
for lower
6EN1558
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Base Engine Service Procedure
C
8
4
1
7
3
2
5
6
9
10
6EN0624
Bearing cap/bearing cap bolt installation
(1) Install the bearing caps so that their arrows are
positioned on the timing belt side.
(2) When installing the bearing cap bolts, check that the
shank length of each bolt meets the limit. If the limit is
exceeded, replace the bolt.
Limit: Max. 71.1 mm (2.799 in.)
(3) Torque the bearing cap bolts to 2.5 kgf•m (18.1 lb•ft)[25
N•m] and, from that position, retighten them 1/4 (90°)
turns more.
Caution:
1) If the bolt is turned less than 90°, proper fastening
performance may not be expected. When tightening the
bolt, therefore, be careful to give a sufficient turn to it.
2) If the bolt is over tightened (exceeding 100°), loosen the
bolt completely and then retighten it by repeating the
tightening procedure from step (1).
(4) After installing the bearing caps, make sure that the end
play is correct. If the end play exceeds the limit, replace
the crankshaft bearings.
Standard value: 0.05 to 0.25 mm (0.0020 to 0.0098 in.)
Limit: 0.4 mm (.016 in.)
6EN0625
D
Oil seal installation
MB990938
(1) Using the special tool, knock, the oil seal into the oil seal
case.
MD998776
6EN0709
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167
Base Engine Service Procedure
E
Sealant application to oil seal case.
Specified sealant: Silicone RTV sealant or equivalent.
Seal ant
NOTE:
1) Be sure to install the case quickly while the sealant is
wet(within 15 minutes).
2) After installation, keep the sealant area away front the oil
and coolant for approx. one hour.
6EN0626
F
Rear plate installation
(1) Be sure install the spring washers and special washers in
correct position.
Spring
washer
Special washer
6EN1919
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168
Base Engine Service Procedure
ADJUSTING AND TROUBLESHOOTING
Adjustment
The following is the method of adjustment of the
carburetor and pneumatic governor on a reassembled
engine.
Gasoline
Rubber cap
Caution :
(1) The pneumatic governor hss been properly
adjusted and sealed in the factory before shipping.
Never break the seal unless it is necessary during
engine overhaul.
(2) If the pneumatic governor is readjusted, seal it
again and advise your user that he should not
break the seal.
Vacuum hose
1. Valve Clearance Adjustment
Being adjusted automatically with a lash adjuster, the
valve clearance needs no adjustment.
LPG
2. Ingition Timing Adjustment
Rubber cap
(1) Let the engine warm up until the engine coolant
temperature rises to 80 to 95°C (176 to 203°F).
(2) Remove the vacuum hose at throttle body side and
plug open end of the nipple with something like
rubber cap.
(3) Connect the timing light to the No.1 spark plug,
and connect the power-supply leads of the light to
12V battery.
(4) Aim the timing light at the timing indicator at the
crankshaft pulley.
Vacuum hose
(5) Check that ignition timing is as indicated when the
engine is running at idling speed.
Standard value :
Gasoline 4°BTDC/740 rpm
LPG
9°BTDC/740 rpm
Mounting
nut
(6) If not within the standard value, loosen distributor
fixing nuts and adjust by rotating distributor body.
Distributor
(7) Tighten the mounting nuts after adjusting.
(8)Remove the rubber cap and connect the vacuum
hose as it was.
To retard
To advance
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169
Adjustment and Troubleshooting
NOTE
Engine timing can be measured at not only engine
crankshaft pulley but also flywheel assy. The
measurement of engine timing at crankshaft pulley is
exact but it is difficult and dangerous. The
measurement of engine timing at flywheel side is safe,
but it is need to adjust zero position of timing plate like
the followings brfore measurement of engine timing.
1) Pull out key from key switch.
2) Remove timing plate(6) from the converter housing.
The flywheel shoulder has a single timing mark on
it. Put a white chalk mark on it, so it can be seen
more easily.
3) Rotate timing plate (6) 180° and mount it on the
converter housing again, using the other mounting
holes on plate (6). When plate (6) is mounted, the
timing marks should be close to the flywheel as
shown.
6
4) Rotate engine and align the timing mark of engine
crankshaft pulley to zero degree position of timing
indicator near crankshaft balancer.
5) Note the timing mark on the flywheel indicates
which position of timing plate(6). If timing mark does
not indicate zero degree position of timing plate(6),
the correct zero position should be marked on the
timing plate.
IDES096S
Timing Plate In Stored Position
(6) Timing Plate.
6
IDES097S
Timing Plate Rotated 180°
(6) Timing Plate.
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170
Adjustment and Troubleshooting
(3) While holding the adjust screw to prevent it from
turning, rotate the adjusting nut either clockwise or
counterclockwise to make the engine run at 2700
L 50 rpm.
3. Idling Speed Adjustment
Gasoline Carburetor
Adjusting nut:
Clockwise rotation
Increases the engine speed (increases the
installed load of spring).
Counterclockwise rotation
Decreases the engine speed (decreases the
engine installed load of spring).
SAS
5. Anti-Hunting Adjustment
MAS
Governor Characteristics
Larger spring
rigidity
Smaller spring
rigidity
Out put (PS)
(1) Let engine warm up until the engine coolant
temperature rises to 80 to 95°C (176 to 203°F)
(2) Back off the mixture adjussting screw (MAS)
3.5L0.5 turns.
(3) Adjust the engine speed to the specified low idling
speed with the speed adjusting screw (SAS).
standard value : 700L25rpm
Engine Speed (rpm)
(4) Slowly turn down the mixture adjusting
screw(MAS) to a point where the engine speed
begins to decrease.
6EN0836
(1) Place all the hydraulic levers or powertrain in the
neutral position.
(2) Depress the accelerator pedal all the way. (The
carburetor throttle valve will open fully.)
(3) Slowly rotate the adjusting screw clockwise until
hunting disappears.
(5) After racing the engine two or three times (at
approx .2500 rpm), re-adjust the speed adjusting
screw to the point at which the engine rust at the
specified idling speed.
Adjusting screw:
Clockwise rotation
Increases spring tension (reduces the number
of active turns of spring).
Counterclockwise rotation
Reduces spring tension (increases the
number of active turns of spring).
LP Gas Carburetor
See “Tests & Adjustments” of LP Fuel System Section.
4. Air Governor Adjustment
High speed adjustment
Increasing the spring tension will eliminate hunting,
but an excessively high tension will change the
governor characteristics and produce some effects
on the output characteristics of the engine. It is,
therefore, imperative to limit the movement of the
adjusting screw to less than two turns from the
standard position.
(4) Clockwise rotation of the adjusting screw raises
the engine maximum speed. Rotate the push nut
counterclockwise to reduce the speed.
(5) Repeat anti-hunting adjustment two or three times
by alternately adjusting the push nut and the
adjusting screw until the best result is obtained.
(6) The number of active turns of spring should be
around 13~15 when the adjustment is finished.
Screw
Adjusting nut
6EN0835
(1) Place all the hydraulic levers in the neutral
position.
(2) Depress the accelerator pedal all the way. (The
carburetor throttle valve will open fully.)
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171
Adjustment and Troubleshooting
Troubleshooting
Engine Performance
Symptom
Cause
1. Poor engine idle.
A. Clogged air breather.
B. Improper idle-fuel mixture adjustment.
C. Cap or spark-plug wires arcing.
D. Low grade fuel.
E. Incorrect ignition timing.
F. Spark plugs (fouled, burned, cracked porcelain).
G. Spark plug wires broken or faulty insulation.
H. Defective coil.
I. Cracked or dirty distributor cap.
J. Dirty carburetor.
K. Leak at intake manifold or carburetor base.
L. Low compression. (Check for blown head gasket).
M. Loose or worn distributor.
N. Head gasket, exhaust manifold, cracked head or valve seat.
2. Poor engine acceleration.
A. Idle mixture screw.
B. Incorrect ignition timing.
C. Incorrect distributor advance curve.
D. Cracked or dirty distributor cap or rotor.
E. Vacuum leak on the intake manifold or carburetor base.
F. Spark plugs (fouled, burned, wrong heat range, cracked porcelain).
G. Dirty carburetor.
H. Low compression.
Engine Starting Problems
The following information will help to locate the starting problem:
1. Determine which engine system is causing the problem. To make an engine run, basic components - fuel,
spark (ignition) and compression - are required. If all three components are present, the engine should run. If
any one of the three is missing, weak or arriving at the wrong time, the engine will not run.
2. Determine if there is fuel present.
3. Check ignition system operation. Using appropriate spark tester, check for spark at coil and at each spark plug.
If there is a spark at the spark plug wires, remove the spark plugs and make sure they are the correct type and
heat range, and not fouled or burned.
4. Run a compression check on the engine to make sure it is mechanically sound.
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172
Adjustment and Troubleshooting
Engine Starting Problems (Continued)
Symptom
Cause
1. No spark.
A. Distributor cap or spark plug leads arcing.
B. Spark plugs fouled, burned or cracked porcelain.
C. Spark plug wires are broken or have faulty insulation.
D. Battery, electrical connections, damaged wiring.
E. Ignition switch.
F. Faulty ignition components.
G. Cracked or dirty distributor cap.
H. Shorted tachometer. (Disconnect tachometer and try again).
2. Engine will not crank over.
A. Battery charge low, damaged wiring or loose electrical connections.
B. Circuit breaker tripped (if equipped).
C. Bad ignition switch.
D. Bad starter solenoid.
E. Defective starter motor.
Charging System Problems
Symptom
Cause
1. Gauges indicate no
battery charge.
A. Loose or broken drive belt.
B. Loose or corroded electrical connections.
C. Faulty ammeter or voltmeter.
D. Battery will not accept charge.
E. Faulty alternator or regulator.
2. Noisy alternator.
A. Loose mounting bolts.
B. Worn, frayed or loose drive belt.
C. Loose drive pulley.
D. Worn or dirty bearings.
E. Faulty diode trio or stator.
Instrument Problems
Symptom
1. Malfunctioning
instruments or gauges.
G424 Service Manual
Cause
A. Faulty wiring, loose or corroded terminals.
B. Bad key switch.
C. Faulty gauge.
D. Faulty sender.
173
Adjustment and Troubleshooting
Engine Noise
No definite rule or test will positively determine the
source of engine noise. Therefore, use the following
information only as a general guide to engine noise
diagnosis.
4. Try to isolate the noise to location in engine, front
to back, top to bottom. This can help determine
which components are at fault.
5. Sometimes noises can be caused by moving parts
coming in contact with other components.
Examples are: flywheel, crankshaft striking (pan
and pan baffle), rocker arm striking valve cover or
loose flywheel cover. In many cases, if this is
found to be the problem, a complete engine
teardown is not necessary.
1. Use a timing light to determine if noise is timed
with engine rpm or one-half engine rpm. Noises
timed with engine rpm are related to crankshaft,
rods, pistons, piston pins or flywheel. Noises timed
to one-half engine rpm are valve-train related.
2. The use of a stethoscope can aid in locating a
noise source. However, because noise will travel
to other metal parts not involved in the problem,
caution must be exercised.
6. When noise is isolated to a certain area and
component, removal and inspection will be
required. Refer to proper sections of service
manual for pertinent information.
3. If noise is believed to be confined to one particular
cylinder, ground the spark plug leads one at a
time. If noise lessens noticeably or disappears, it is
isolated to that particular cylinder.
Symptom
Cause
1. Noise around the
valve cover area.
A. Rocker arm striking valve cover.
B. Rocker arm out of adjustment.
C. Worn rocker arm.
D. Bent push rod.
E. Collapsed lifter.
2. Noise around the
cylinder area.
A. Sticking valve.
B. Carbon build-up.
C. Connecting rod installed wrong.
D. Bent connecting rod.
E. Piston.
F. Piston rings.
G. Piston pin.
H. Cylinder worn.
3. Noise around camshaft
area (throughout engine).
A. Loss of oil pressure.
B. Valve lifters.
C. Cam bearings.
4. Noise in camshaft area
area (front of engine).
A. Camshaft timing gear.
B. Timing Belt.
C. Valve lifter.
D. Cam bearings.
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Adjustment and Troubleshooting
Engine Noise (Continued)
Symptom
Cause
5. Noise in camshaft area
(center of engine).
A. Valve lifter.
B. Cam bearings.
6. Noise in camshaft area
(rear of engine).
A. Valve lifter.
B. Cam bearings.
7. Noise in crankshaft area
(throughout engine).
A. Loss of oil pressure.
B. Main bearings.
C. Rod bearings.
8. Noise in crankshaft area
(front of engine).
A. Crankshaft timing gear.
B. Timing Belt.
C. Main bearing.
D. Rod bearing.
9. Noise in crankshaft area
(center of engine).
A. Crankshaft striking pan or pan baffle.
B. Main bearing.
C. Rod bearing.
10. Noise in crankshaft area
(rear of engine).
A. Loose flywheel.
B. Drive plate.
C. Main bearing.
D. Rod bearing.
11. Engine spark knock.
A. Advanced timing.
B. Low quality fuel.
C. Engine running hot.
D. Carbon deposits in engine.
12. Popping through
carburetor.
A. Wrong ignition timing.
B. Carburetor set too lean.
C. Faulty accelerator pump (gasoline).
D. Vacuum leak.
E. Valve adjustment.
F. Valve timing.
G. Burned or stuck valve.
13. Hissing.
A. Vacuum leak.
B. Leaking exhaust (manifolds or pipes).
C. Loose cylinder heads.
D. Blown head gasket.
14. Whistle.
A. Vacuum leak.
B. Dry or tight bearing in an accessory.
15. Sparks jumping.
A. Defective high-tension cables.
B. Cracked coil tower.
C. Cracked distributor cap.
16. Squeaks or squeals.
A. Drive belt slipping.
B. Dry or tight bearing in an accessory.
C. Parts rubbing together.
G424 Service Manual
175
Adjustment and Troubleshooting
Oil Pressure Diagnostics
The following table contains important information for the checking of oil pressure.
Condition
Information
1. Measuring oil pressure.
Use a good automotive oil pressure test gauge. Do not rely on the oil
pressure gauge in the instrument panel.
2. Check engine oil level.
Oil level should be between the "MIN" and "MAX" marks.
3. Oil level in crankcase
above "MAX" mark.
May cause loss of engine speed, oil pressure gauge
fluctuation, drop in oil pressure and hydraulic valve lifter noise at high RPM.
4. Oil level in crankcase
Low oil pressure, oil pressure gauge fluctuation, internal below at or below
"MIN" mark. engine noise and/or damage.
5. Change in oil pressure.
This may be a normal condition. Oil pressure may read high in the cooler
times of the day and when engine is not up to operating temperature. As
the air temperature warms up and the engine is running at normal operating
temperature, it is normal for oil pressure to drop off slightly.
6. Low engine oil pressure
With modern engines and engine oils, low oil pressure readings at idle or
high rpm do not necessarily mean there is a problem. If valve lifters do not
"clatter" (at idle), there is a sufficient volume of oil to lubricate all internal
moving parts properly. The reason for the drop in oil pressure is that engine
heat causes an expansion of the internal tolerances in the engine and, the
oil will thin out somewhat from heat.
7. Engine-to-engine variance.
It is not uncommon to see different oil pressure readings between like
engines, as long as they fall within specifications. Differences in oil
pressure can be attributed to differences in engine tolerances, gauges,
wiring, senders, etc.
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176
Adjustment and Troubleshooting
Oil Pressure Problems
Symptom
Cause
1. Low oil pressure.
A. Low oil level in crankcase.
B. Defective oil-pressure gauge and/or sender.
C. Oil broken down, contains water, wrong viscosity, engine running too hot
or too cold, excessive idling with cold water (condensation).
D. Relief valve stuck open, pickup tube restricted, worn parts in oil pump,
air leak on suction side of oil pump or pickup tube.
E. Oil passage plugs leaking, cracked or porous cylinder block.
F. Excessive bearing clearance.
2. High oil pressure.
A. Wrong viscosity, oil full of sludge or tar.
B. Defective oil pressure gauge and/or sender.
C. Clogged or restricted oil passage.
D. Oil pump relief valve stuck closed.
IMPORTANT: Oil pressure slightly higher than normal does not always indicate a problem.
Tolerance stack-up In the engine, oil viscosity or weather conditions could cause high oil pres-sure.
3. Excessive oil consumption.
G424 Service Manual
A. Oil leaks.
B. Oil diluted or of the wrong viscosity.
C. Oil level too high.
D. Drain holes in cylinder head plugged causing flooding of valve guides.
E. Defective valve seals.
F. Intake manifold gasket leaking, worn valve stem or valve guides.
G. Defective oil cooler (if so equipped).
H. Glazed, scuffed, worn, stuck, improperly installed; ring grooves worn;
improper break-in; wrong end gap.
I. Piston out-of-round, scored, tapered, glazed; excessive piston-to-cylinder
clearance; cracked piston.
177
Adjustment and Troubleshooting
Water in Engine
Determine location of water in engine. This information is necessary to determine where the water came from and
how it got into the engine. The most common problems are water on top of pistons and/or water in crankcase oil.
1. After locating the water, remove all the water from the engine by removing all spark plugs and pump cylinders
by cranking engine over. Next change oil and filter. Start engine and see if problem can be duplicated. If so,
there is more than likely a mechanical problem. If problem cannot be duplicated, it is either an operator error or
a problem that exists only under certain environmental conditions.
2. If water is confined to cylinders, it is usually entering through the intake system, exhaust system or head
gasket.
3. If the water is confined to crankcase, it is usually caused by a cracked or porous block or condensation.
4. If the water is located in both the cylinders and the crankcase, it is usually caused by water in the cylinders
getting past the rings and valves.
5. Checking for rust in the intake manifold or exhaust manifolds is a good idea. Rust in these areas will give clues
if the water entered through these areas.
Symptom
Cause
1. Water found on top of
the pistons.
A. Cracked exhaust manifold (water cooled).
B. Improper manifold-to-elbow gasket installation (water cooled).
C. Loose cylinder head bolts.
D. Blown cylinder head gasket. (Check for warped cylinder head or cylinder
block).
E. Cracked valve seat.
F. Porous or cracked casting (check engine).
2. Water found in the
crankcase oil.
A. Water seeping past piston rings or valves.
B. Engine running cold (defective thermostat) causing condensation.
C. Intake manifold leaking near a water passage.
D. Cracked or porous casting.
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178
Adjustment and Troubleshooting
Engine Overheating
Symptom
Cause
1. Mechanically related.
A. Engine rpm below specification for W.O.T. (engine laboring).
B. Wrong ignition timing.
C. Spark plug wires crossed (wrong firing order).
D. Lean fuel mixture.
E. Wrong heat range spark plugs.
F Exhaust restriction.
G. Valve timing off caused by a jumped or improperly installed timing chain
and/or gears.
H. Blown head gasket(s).
I. Insufficient lubrication to moving parts of engine.
2. Cooling system related.
A. Loose or broken drive belt.
B. Water shut-off valve partially or fully closed (if equipped).
C. Clogged or improperly installed water strainer (if equipped).
D. Water inlet hose kinked or collapsed.
E. Water pickup clogged.
F. Defective thermostat.
G. Obstruction in cooling system such as casting flash, sand, or rust.
H. Engine circulating pump defective.
I. Low coolant level.
J. Antifreeze not mixed properly.
K. Heat exchanger cores plugged.
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179
Adjustment and Troubleshooting
LP Fuel System (Standard and/or Low Emission Version)
Problem
Will Not Start/FCV
Staying On
Probable Cause
Fuel container empty
Liquid valve closed
Excess flow valve closed
Plugged fuel line
Clogged fuel filter
Faulty vapor connection
between pressure regulator
and carburetor
Fuel lock malfunction
Pressure regulator
malfunction
Will Not Start/FCV
Staying On
Carburetor malfunction
Air filter plugged
No spark
Engine Mechanical
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180
Probable Solution
Fill fuel container
• Do not exceed 80% of liquid capacity.
Open liquid valve slowly
Reset excess flow valve
• Close liquid valve
• Wait for click sound
• Open valve slowly
Remove obstruction from fuel line
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Clear obstruction with compressed air
• Re-connect fuel line
• Leak test
Repair/replace as required
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Remove/replace filter element
• Clean fuel filter housing
• Open liquid fuel valve
• Leak test
Check connection
• No holes in hose
• Clamps must be tight
• Watch for kinked and/or pinched
and/or collapsed hose
• Check circuit wiring
• Check safety switch
• Check fuelock
• Repair/replace fuelock as required
Test pressure regulator operation
• Use test kit
• Install primary pressure gauge
• Install secondary pressure gauge
• Crank engine and observe readings
on pressure gauges
• Compare readings to specifications
• If readings are out of spec
repair/replace pressure regulator
Check carburetor
•Remove air/gas valve assembly
• Clean air/gas valve and carb throat
• Check diaphragm for holes/damage
• Check air/gas valve for wear/damage
• Repair/replace as required
Check air filter
• Clean/replace as required
Check for spark
• See, lgnition system sectiom
• Repair/replace as required
See Troubleshooting section
Adjustment and Troubleshooting
Problem
Difficult to Start
Probable Cause
Fuel container almost empty
Excess flow valve closed
Clogged fuel filter
Plugged fuel line
Faulty vapor connection
between pressure regulator
and carburetor
Pressure regulator
malfunction
Air filter clogged
Engine Mechanical
G424 Service Manual
181
Probable Solution
LPG vapor from liquid outlet
• Fill fuel container
• Do not exceed 80% of liquid capacity
Reset excess flow valve
• Close liquid valve
• Wait for click sound
• Open valve slowly
Repair/replace as required
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Remove/replace filter element
• Clean fuel filter housing
• Open liquid fuel valve
• Leak test
Remove obstruction from fuel line
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Clear obstruction with compressed air
• Re-connect fuel line
• Leak test
Check connection
• No holes in hose
• Clamps must be tight
• Watch for kinked and/or pinched
and/or collapsed hose
Test pressure regulator operation
• Use test kit
• Install primary pressure gauge
• Install secondary pressure gauge
• Crank engine and observe readings
on pressure gauges
• Compare readings to specifications
• If readings are out of specrepair/replace
pressure regulator
Check air filter
• Clean/replace as required
See Troubleshooting section
Adjustment and Troubleshooting
Problem
Won’t Run Continuously
Probable Cause
Fuel container almost empty
Excess flow valve closed
Clogged fuel filter
Plugged fuel line
Faulty vapor connection
between pressure regulator
and carburetor
Pressure regulator freezes
Incorrect idle speed
Engine Mechanical
Won’t
Accelerate/Hesitation
During Acceleration
Fuel container almost empty
Excess flow valve closed
Clogged fuel filter
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182
Probable Solution
LPG vapor from liquid outlet
• Fill fuel container
• Do not exceed 80% of liquid capacity
Reset excess flow valve
• Close liquid valve
• Wait for click sound
• Open valve slowly
Repair/replace as required
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Remove/replace filter element
• Clean fuel filter housing
• Open liquid fuel valve
• Leak test
Remove obstruction from fuel line
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Clear obstruction with compressed air
• Re-connect fuel line
• Leak test
Check connection
• No holes in hose
• Clamps must be tight
• Watch for kinked and/or pinched
and/or collapsed hose
Check level in cooling system
• Must be full
Check coolant strength
• -35F minimum
Check coolant hoses
• Watch for kinks and/or pinched hoses
• Verify one pressure hose and one return
hose
Check idle speed
• Adjust idle speed to specification
See Troubleshooting section
LPG vapor from liquid outlet
• Fill fuel container
• Do not exceed 80% of liquid capacity
Reset excess flow valve
• Close liquid valve
• Wait for click sound
• Open valve slowly
Repair/replace as required
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Remove/replace filter element
• Clean fuel filter housing
• Open liquid fuel valve
• Leak test
Adjustment and Troubleshooting
Problem
Won’t Run Continuously
Accelerate/Hesitation
During Acceleration
Probable Cause
Faulty vapor connection
between pressure regulator
and carburetor
Probable Solution
Check connection
• No holes in hose
• Clamps must be tight
• Watch for kinked and/or pinched and/or
collapsed hose
Throttle butterfly not opening Verify wide open throttle
Incorrect full load air/fuel duty Verify full load air/fuel duty cycle
cycle
Engine Mechanical
See Troubleshooting section
Engine Stalls
Idle duty cycle too high
(above 50%)
Fuel container almost empty
Excess flow valve closed
Clogged fuel filter
Plugged fuel line
Faulty vapor connectionr
between pressure regulator
and carburetor
Vacuum leak
Fuel lock malfunction
G424 Service Manual
183
Correct/adjust hardware failure
LPG vapor from liquid outlet
• Fill fuel container
• Do not exceed 80% of liquid capacity
Reset excess flow valve
• Close liquid valve
• Wait for click sound
• Open valve slowly
Repair/replace as required
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Remove/replace filter element
• Clean fuel filter housing
• Open liquid fuel valve
• Leak test
Remove obstruction from fuel line
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Clear obstruction with compressed air
• Re-connect fuel line
• Leak test
Check connection
• No holes in hose
• Clamps must be tight
• Watch for kinked and/or pinched and/or
collapsed hose
Check for vacuum leaks
• Between carburetor and intake manifold
• Between intake manifold and cylinder head
• Check circuit wiring
• Check safety switch
• Check fuelock
• Repair/replace fuelock as required
Adjustment and Troubleshooting
Problem
Engine Stalls
Probable Cause
Pressure regulator
malfunction
Pressure regulator freezes
Faulty vapor connection
between pressure regulator
and carburetor
Carburetor malfunction
Engine Mechanical
Rough Idle/Weak
Ignition/Lean Condition
Incorrect idle speed setting
Incorrect full load air/fuel duty
cycle
Faulty vapor connection
between pressure regulator
and carburetor
Vacuum leaks
High Idle Speed
Engine mechanical
Incorrect idle speed setting
Sticking throttle
Engine mechanical
G424 Service Manual
184
Probable Solution
Test pressure regulator operation
• Use test kit
• Install primary pressure gauge
• Install secondary pressure gauge
• Crank engine and observe readings on
pressure gauges
• Compare readings to specifications
• If readings are out of spec repair/replace
pressure regulator
Check level in cooling system
• Must be full
Check coolant strength
• -35F minimum
Check regulator mounting position
• Must be below top of radiator
Check coolant hoses
• Watch for kinks and/or pinched hoses
• Verify one pressure hose and one return
hose
Check connection
• No holes in hose
• Clamps must be tight
• Watch for kinked and/or pinched and/or
collapsed hose
Check carburetor
• Remove air/gas valve assembly
• Clean air/gas valve and carb throat
• Check diaphragm for holes/damage
• Check air/gas valve for wear/damage
• Repair/replace as required
See Troubleshooting section
Check idle speed and adjust if necessaly
Verify full load air/fuel duty cycle
Check connection
• No holes in hose
• Clamps must be tight
* Watch for kinked and/or pinched and/or
collapsed hose
Check for vacuum leaks
• Between carburetor and intake manifold
• Between intake manifold and cylinder head
See Troubleshooting section
Check idle speed
• Adjust idle speed
Check throttle
• Repair replace as required
See Troubleshooting section
Adjustment and Troubleshooting
Problem
Carburetor Backfire
Probable Cause
Incorrect full load air/fuel duty
cycle
Faulty vapor connection
between pressure regulator
and carburetor
Ignition malfunction
Incorrect ignition timing
setting
Clogged fuel filter
Plugged fuel line
Faulty vapor connection
between pressure regulator
and carburetor
Throttle butterfly not opening
Incorrect full load air/fuel duty
cycle
Carburetor malfunction
Pressure regulator
malfunction
Incorrect ignition timing
setting
Air filter clogged
G424 Service Manual
Check connection
• No holes in hose
• Clamps must be tight
• Watch for kinked and/or pinched and/or
collapsed hose
Check ignition system, repair/replace
Check ignition timing
• Measure initial timing
• Measure centrifugal timing advance
See Troubleshooting section
Engine mechanical
Poor High Speed
Performance/Lean
Condition
Probable Solution
Verify full load air/fuel duty
185
Repair/replace as required
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Remove/replace filter element
• Clean fuel filter housing
• Open liquid fuel valve
• Leak test
Remove obstruction from fuel line
• Close liquid fuel valve
• Using caution, disconnect fuel line
• Clear obstruction with compressed air
• Re-connect fuel line
• Leak test
Check connection
• No holes in hose
• Clamps must be tight
• Watch for kinked and/or pinched and/or
collapsed hose
Verify wide open throttle
Verify full load air/fuel duty cycle
Check carburetor
• Remove air/gas valve assembly
• Clean air/gas valve and carb throat
• Check diaphragm for holes/damage
• Check air/gas valve for wear/damage
• Repair/replace as required
Test pressure regulator operation
• Use test kit
• Install primary pressure gauge
• Install secondary pressure gauge
• Crank engine and observe readings on
pressure gauges
• Compare readings to specifications
• If readings are out of spec repair/replace
pressure regulator
Check ignition timing
• Measure initial timing
• Measure centrifugal timing advance
Check air filter
• Clean/replace as required
Adjustment and Troubleshooting
Problem
Poor High Speed
Performance/Lean
Condition
Probable Cause
Restricted exhaust system
Engine mechanical
Excessive Fuel
Consumption/LPG
Exhaust Smell/Closed
Loop System Not
Working
Carburetor malfunction
Incorrect ignition timing
setting
Incorrect full load air/fuel duty
cycle
Engine mechanical
Pressure regulator
malfunction
Check carburetor
• Remove air/gas valve assembly
• Clean air/gas valve and carb throat
• Check diaphragm for holes/damage
• Check air/gas valve for wear/damage
• Repair/replace as required
Check ignition timing
• Measure timing @ low idle
• Measure timing advance @ run
Verify full load air/fuel duty cycle
See Troubleshooting section
Test pressure regulator operation
• Use test kit
• Install primary pressure gauge
• Install secondary pressure gauge
• Crank engine and observe readings on
pressure gauges
• Compare readings to specifications
• If readings are out of spec repair/replace
pressure regulator
Check air filter
• Clean/replace as required
See ignition system section
Replace fuel system vacuum hoses
Replace/rebuild regulator.
Repair exhaust system
Replace/reconnect oxygen sensor
Replace/reconnect FCV
Replace/reconnect commander
Air filter clogged
Weak ignition miss fire
Vacuum Leak
Fuel pressure too high
Exhaust system leaks
Oxygen sensor failure
FCV failure
Commander failure
G424 Service Manual
Probable Solution
Check exhaust system
• Measure exhaust back-pressure
• Compare to specs
See Troubleshooting section
186
Adjustment and Troubleshooting
Troubleshooting Flow Chart
General
Abnormal
combustion
Loose connection in ignition system wiring
–Check connections and retighten.
Defective spark plug
–Replace spark plug.
Incorrect ignition timing
–Adjust ignition timing.
Defective carburetor
–Repair or replace carburetor.
Contaminated or clogged fuel filter element
and pipe
–Clean fuel filter element and pipe.
Entry of air from carburetor or intake manifold
–Retighten set bolts or replace heat
insulator and/or intake manifold gasket.
Valves and related
components
Defective valves and related components
–Adjust or repair valves and related
components.
Cylinder head
Carbon deposited in combustion chamber
–Disassemble and clean.
Clogged cylinder head water tube
–Clean or replace water tube.
Cylinder gasket blow-by
–Replace gasket.
Ignition system out
of adjustment
Incorrect ignition timing
–Adjust ignition timing.
Defective spark plug
–Replace spark plug.
Insufficient fuel
Defective carburetor
–Repair or replace carburetor.z
Damaged cylinder head gasket, etc.
–Replace gasket.
Clogged fuel pipe
–Clean pipe.
Clogged fuel filter
–Clean or replace.
Air in fuel system
–Check connections and retighten.
Damaged fuel pipe
–Replace pipe.
Fuel pump not functioning properly
–Repair or replace.
Ignition system
Carburetion related
components
Insufficient
output
Insufficient intake
air in carburetor
Overheating
G424 Service Manual
Damaged diaphragm
–Replace.
Defective valve
–Replace.
Clogged air cleaner element
–Clean or replace element.
Carburetor choke always in operation
–Repair or replace carburetor.
Air governor malfunction
–Repair or replace air governor.
Insufficient coolant
–Add coolant and check for leaky points.
Leaks from radiator
–Repair or replace radiator.
Loosened or damaged radiator
hose connection
–Retighten clamp or replace hose.
Leaks from water pump
–Replace.
Coolant leaks from cylinder head gasket
–Retighten cylinder head bolts or replace
gasket.
Cracks in cylinder head or block
–Replace.
187
Adjustment and Troubleshooting
Insufficient
output
Poor
acceleration
Excessive
fuel
consumption
Excessive
engine oil
consumption
Loose fan belt tension
–Adjust or replace.
Worm or damaged fan belt
–Replace.
Oil on fan belt
–Clean.
Thermostat not functioning properly
–Replace.
Water pump not functioning properly
–Replace.
Clogged radiator
–Clean radiator and coolant passages.
Incorrect ignition timing
–Adjust ignition timing.
Improper engine oil
–Refer to lubrication table and replace oil
with a recommended one.
Too lean mixture
–Repair or replace carburetor.
Incorrect valve clearance adjustment
–Make measurements on or replace autolash adjuster.
Insufficient
compression
pressure
Engine out of order
–Refer to p.189 and make repairs.
Overcooling
(Coolant
temperature does
not rise.)
Defective thermostat
–Replace thermostat.
Extremely low atmospheric temperature
–Place cover or anything proper on the
front of radiator.
Engine
Engine out of order
–Refer to p.189 and make repairs.
Carburetor
Carburetor out of order
–Replace or replace distributor.
Ignition system
Defective distributor
–Repair or replace distributor.
Defective spark plug
–Replace spark plug.
Engine
Engine out of order
–Adjust of repair valves.
Carburetor
Defective carburetor
–Repair or replace carburetor.
Clogged air bleeder
–Clean or replace.
Damaged gaskets
–Replace.
Improper idling speed
–Adjust idling speed.
Ignition system
Incorrect ignition timing
–Adjust ignition timing.
Excessive engine
oil consumption
Engine out of order
–Refer to p.189 and make repairs.
Oil leaks
Engine out of order
–Refer to p.189 and make repairs.
Overheating
G424 Service Manual
188
Adjustment and Troubleshooting
Base Engine
Valves and
related
components
Poor idling
Abnormal
combustion
Insufficient output
Excessive fuel
consumption
Engine
Poor startability
Poor acceleration
Excessive fuel
consumption
Insufficient output
Incorrect valve clearance
–Cleaned or replace auto-lash adjuster.
Valve not in close contact with valve seat
–Reface seat surface.
Excessive clearance between valve stem
and valve guide
–Replace valve and valve guide.
Incorrect valve clearance
–Cleaned or replace auto-lash adjuster.
Valve binding
–Disassemble, correct or replace.
Deteriorated valve spring
–Replace spring.
Incorrect valve clearance
–Cleaned or replace auto-lash adjuster.
Pressure leaks from valve seal
–Reface.
Valve stem seizure
–Repair or replace.
Deteriorated or broken valve spring
–Replace spring.
Valve damaged by heat
–Reface or replace valve.
Intake manifold gasket not tight enough
–Retighten set bolts or replace gasket.
Cylinder head gasket blow-by
–Replace gasket.
Valve damaged by heat or not properly
serviced
–Adjust or replace.
Insufficient compression pressure
–Disassemble and repair engine.
Cylinder head gasket blow-by
–Replace gasket.
Pressure leaks from cylinder head gasket
Piston ring binding or worn
–Retighten cylinder head bolts and
replace gasket.
–Replace ring.
Piston ring or ring worn
–Disassemble and repair engine.
Oil leaks
Excessive oil
consumption
G424 Service Manual
Loose oil drain plug
–Retighten plug.
Loose oil pan set bolts
–Retighten set bolts.
Damaged oil pan gasket
–Replace gasket.
Loose timing gear cover or damaged gasket
–Retighten set bolts or replace gasket.
Defective crankshaft front oil seal
–Replace oil seal.
Defective crankshaft rear oil seal
–Replace oil seal.
Damaged cylinder head gasket
–Replace gasket.
Loose oil filter set bolt.
–Retighten set bolts or replace oil filter
gasket.
189
Adjustment and Troubleshooting
Oil working its way up
Engine
Excessive oil
consumption
Piston ring gaps in improper positions
–Adjust ring gap positions.
Piston rings or ring grooves worn or rings
–Replace piston or rings.
seized in grooves
Carbon deposit in oil return hole of oil ring
–Replace rings.
Worn piston and cylinder
–Rebore and hone cylinder and install
oversize piston.
Excessive quantity of oil in oil pan
–Oil quantity: 4.0 liter (1.1 U.S. gal).
Oil working its way down
Excessive engine
noise
G424 Service Manual
Worn valve stem and valve guide
–Replace valve and guide.
Defective valve stem oil seal
–Replace oil seal
Excessive oil clearance due to worn
crankshaft bearing
–Replace bearing.
Fusion in crankshaft bearing
–Replace bearing and check lubrication
system.
Worn connecting rod bearing
–Replace bearing.
Bent connecting rod
–Repair bent connecting rod or replace.
Fusion in connecting rod bearing
–Replace bearing and check lubrication
system.
Excessive clearance due to worn cylinder
–Rebore and hone cylinder and install
oversize piston.
Worn piston or piston pin
–Replace piston and piston pin.
Piston seizure
–Replace piston.
Broken piston ring
–Replace piston ring.
Excessive camshaft end play
–Replace camshaft thrust plate.
Worn crankshaft thrust bearing
–Replace bearing.
Worn timing gears
–Replace.
Excessive valve clearance
–Cleaned or replace auto-lash adjuster.
190
Adjustment and Troubleshooting
Carburetor
Poor engine
startability
Poor idle
Carburetor
Abnormal
combustion
Poor acceleration
Insufficient output
Excessive fuel
consumption
G424 Service Manual
Needle valve and valve seat not seating
properly
–Clean or replace
Incorrect float level
–Adjust
Worn float lip
–Replace
Worn float level pin and related components
–Replace level pin and its related parts
Malfunction choke valve
–Repair
Idle rpm set out of adjustment
–Adjust idling speed
Damaged idle adjust screw
–Replace adjust screw
Clogged idle passage or idle port
–Clean
Clogged bypass screw
–Clean jet
Worn throttle shaft
–Replace shaft
Loose vacuum pipe union
–Retighten union
Idling circuit not airtight
–Clean
Incorrect float level
–Replace
Too lean mixture
–Clean or replace
Inner dirty carburetor
–Clean carburetor
Defective float level
–Adjust float
Defective accelerating pump plunger
–Disassemble or replace
Clogged pump jet
–Clean or replace
Defective accelerating linkage
–Replace linkage
Malfunction power piston
–Replace power piston
Malfunction power valve
–Replace
Clogged power jet
–Clean or replace
Float level too low
–Adjust float
Throttle valve not opening completely
–Adjust valve
Clogged main jet
–Clean
Incorrect float level
–Adjust float
Malfunction power piston
–Replace power piston
Malfunction power valve
–Replace power valve
Worn throttle shaft
–Replace shaft
Throttle valve not opening completely
–Adjust valve
Choke valve stuck close
–Repair or replace
Float level too high
–Adjust float
Defective power valve
–Replace valve
Choke valve not opening completely
–Check linkage, replace
Improper idling speed
–Adjust idling speed
191
Adjustment and Troubleshooting
Electrical components
Distributor
Poor engine starting
Cracked distributor cap and burnt or
contaminated cord insertion hole
–Clean or replace.
Poor engine
acceleration
Centrifugal and vacuum advance device
malfunction
–Repair or replace.
Improper spark plug gap
–Adjust or replace.
Carbon deposit in spark plug
–Clean or replace.
Improper heat range of spark plug
–Replace spark plug with proper one.
Loose or defective plug cord
–Repair or replace.
Defective ignition coil
–Replace ignition coil.
Improperly connected terminals
–Repair.
Switch contacts in loose contact
–Replace switch
Magnet switch contact plate burnt or in
loose contact
–Grind or replace contact plate.
Magnet switch pull-in coil opencircuited
–Replace.
Magnet switch holding coil opencircuited
–Replace.
Brush in loose contact with commutator
as a result of wear
–Reface.
Commutator burnt with consequent poor
conduction of electricity
–Exchange or replace commutators.
High mica of commutator
–Perform under-cutting
Field coil not properly grounded or
short-circuited
–Replace.
Field coil not properly soldered
–Repair.
Armature not properly grounded
–Replace.
Armature short-circuited
–Rewind or replace.
Brush spring broken or with inadequate tension
–Replace spring.
Insufficient engine
output
Excessive fuel
consumption
Spark plug
Poor engine starting
Abnormal
combustion in
engine
Poor engine
acceleration
Insufficient engine
output
Ignition coil
Poor engine staring
Poor engine
acceleration
Starter
Starter does not
rotate
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192
Adjustment and Troubleshooting
Starter
Starter does not
rotate.
Starter rotates but
slowly and
irregularly.
Pinion does not
engage with ring
gear.
Motor continues to
rotate and does not
stop.
G424 Service Manual
Brush holder not properly insulated
–Clean brush or replace holder.
Worn bearing bushing
–Replace bushing.
Wires of armature coil about to be
shortcircuited or grounded
–Rewind or replace.
Field coil not properly connected or
about to be short-circuited
–Repair connections.
Commutator heat-damaged with consequent
poor conduction
–Replace armature.
Brush movement due to damaged or worn
commutator
–Repair or replace.
Commutator vibrating, causing brush to
move
–Repair or replace.
Lifted mica between commutator
segments causing brush to move
–Perform under-cutting
One or two commutator segments
lifted causing brush to move
–Repair or replace.
Commutator in loose contact due
to worn brush
–Repair or replace.
Chipped brush
–Repair or replace.
Worn starter clutch pinion end
–Replace.
Clutch rotates always freely
–Replace.
Deteriorated clutch drive spring
–Replace.
Does not rotate in overrunning direction
–Replace.
Poor sliding of splined section
–Rub surfaces smooth, clean and repair.
Worn bushing
–Replace.
Improper projecting position of magnet
switch pinion
–Adjust with stud bolt.
Worn bearing bushing
–Replace.
Magnet switch coil layer shorted-circuited
–Replace.
Magnet switch contact plate seizure
–Replace.
Starter switch does not return properly
–Replace switch.
193
Adjustment and Troubleshooting
Battery
Run-down battery
Drive belt slipping
–Adjust belt.
Alternator
Stator coil grounded or open-circuited
–Replace or repair.
Rotor coil open-circuited
–Replace.
Brush and slip ring not properly connected
(Brush does not properly come down)
–Replace brush if worn. (Clean holder.)
–Polish slip ring.
Diode short-or open-circuited
–Replace rectifier assembly.
Battery
Short or improper electrolyte
–Add electrolyte and adjust specific gravity.
Defective plates (internal short circuit)
–Replace.
Terminals in loose contact
–Clean and then retighten.
Wiring
Overcharged
battery
G424 Service Manual
Open circuit or loose contact between
key switch and alternator terminals L and R
–Repair.
Burnt fuse of above-mentioned circuits or
holder in loose contact
–Replace fuse and repair contacting
section of holder.
Open circuit or loose contact between
battery and alternator terminal B
–Replace.
Burnt fuse of above-mentioned circuits
or holder in loose contact
–Replace fuse and repair contacting
section of holder.
Defective IC regulator
–Replace.
194
Adjustment and Troubleshooting
SPECIAL TOOLS
Style
G424 Service Manual
Tool No.
Tool name
Use
MD998781
Flywheel stopper
Holding flywheel
MD998785
Sprocket stopper
Holding counterbalance shaft sprocket
MD998778
Crankshaft spocket puller
Removal of crankshaft sprocket
MB990767
End yoke holder
Holding camshaft sprocket
(Use with MD998719)
MD998719
Pulley holding pins
Holding camshaft sprocket when
loosening or torquing bolt (Use
with MB990767)
MD998443
Lash adjuster holder
Retainer for holding lash adjuster in
rocker arm at timer of removal and
installation of rocker arm and rocker
shaft assembly
MD998442
Air bleed wire
Air bleeding of lash adjuster
MD998713
Camshaft oil seal installer Installation of oil seal
MB991654
Cylinder head bolt
wrench(12)
195
Removal and installation of cylinder
head bolt
Special Tools
Style
G424 Service Manual
Tool No.
Tool name
Use
MD998772
Valve spring compressor
Compression of valve spring
MD998729
Valve stem seal installer
Installation of valve stem seal
MD998727
Oil pan remover
Removal of the oil pan
MD998162
Plug wrench
Removal and installation of front
case cap plug
MD998783
Plug wrench retainer
Removal and installation of front case
cap plug
(Use with MD998162)
MD998375
Crankshaft front oil seal
installer
Installation of crankshaft front oil seal
MD998285
Crankshaft front oil seal
guide
Guide for installation of crankshaft front
oil seal
MD998705
Silent shaft bearing
installer
Installation of counterblance shaft front
and rear bearing
MD998371
Silent shaft bearing puller
Removal of counterblance shaft front
bearing
196
Special Tools
Style
G424 Service Manual
Tool No.
Tool name
MD998372
Silent shaft bearing puller
Removal of counterbalance shaft rear
bearing
MD998780
Piston pin setting tool
Removal and installation of piston pin
MD998776
Crankshaft rear oil seal
installer
Installation of crankshaft rear oil seal
MB990938
Handle
Installation of crankshaft rear oil sear
(Use with MD998776)
197
Use
Special Tools
ITK-1 Pressure Gauge Kit
FSA-1000 Fuel System Analyzer
The IMPCO ITK-1 pressure gauge kit is designed
for testing and troubleshooting IMPCO gaseous
fuel systems. The kit contains the following:
See instructions for proper usage to check air/fuel
mixture.
●
0-160 psi gauge - For measuring fuel container
pressure or on dual fuel systems it may be used
to measure gasoline fuel system pressure.
●
0-5 psi gauge - For measuring IMPCO pressure
regulator, primary pressure.
●
0-10” H2O gauge - For measuring IMPCO
pressure regulator, secondary pressure.
●
G2-2 lever gauge - For correct adjustment of the
IMPCO pressure regulator, secondary lever.
●
Assorted fittings
●
Hose
●
Instructions
G424 Service Manual
198
Special Tools