Onan B43 E, B43 G, B48 G Engine Service Manual

965-0757

(Spec A-D)

A-D)

B48G (Spec A-G)

6-88

Prmlsd in USA

Service

Manual

I

-

.-

_--

-..

6

45

Safety Precautions

'

It is recommended that you read your engine manual and become thoroughly acquainted with your equipment before you start the engine.

This symbol if used warns of imme- diate hazards which will

result

in severe personal injury or death.

[AWARNING!

This symbol refers to

8 hazard or unsafe practice which can result in severe personal injury

or

death.

This symbol refers

to a

hazard or unsafe practice which can result in personal injury or product or properiy damage.

Fuels, electrical equipment, batteries, exhaust gases and moving parts present potential hazards that can result in serious, personal injury. Take care in following these recommended procedures.

All local, state and federal codes should be consulted and complied with.

@@!@

This engine tended for

Is

not designed or in-

use

in any type of aircraft.

Use

of

this engine in aircraft can result in engine failure and causes serious personal injury or death.

General

0

Provide appropriate fire extinguishers and install them in convenient locations. Use an extinguisher rated ABC by

NFPA.

0

Make sure that all fasteners on theenginearesecureand accurately torqued. Keep guards in position over fans, driving belts, etc.

0

If it is necessary to make adjustments while the engine is running, use extreme caution when close to hot exhausts, moving parts, etc.

Protect Against Moving Parts

0

Do

not wear loose clothing in the vicinity of moving parts, such as

P i 0 shafts, flywheels, blowers, couplings, fans, belts, etc.

0

Keep your hands away from moving parts.

Batteries

Before starting work on the engine, disconnect batteries to prevent inadvertent starting of the engine.

DO NOT SMOKE while servicing batteries. Lead acid batteries give

off

a highly explosive hydrogen gas which can be ignited by flame, electrical arcing or by smoking.

Verify battery polarity before connecting battery cables.

Connect negative cable last

Fuel

System

DO

NOT fill fuel tanks while engine is running.

DO

engine or fuel tank. Internal combustion engine fuels are highly flammable.

Fuel lines must be of steel piping, adequately secured, and free from leaks. Piping at the engine should be approved flexible line.

Do

not use copper piping for flexible lines as copper will work harden and become brittle enough to break.

Be sure all fuel supplies have a positive shutoff valve.

b

'

Exhaust

System

0

Exhaust products of any internal combustion engine are toxic and can cause injury, or death if inhaled.

All engine applications, especially those within

a

confined area, should be equipped with an exhaust system to discharge gases to the outside atmosphere.

0

Do not use exhaust gases to heat a compartment.

0

Make sure that your exhaust system is free of leaks.

Ensure that exhaust manifolds are secure and are not warped by bolts unevenly torqued.

Exhaust Gas

is

Deadly!

Exhaust gases contain carbon monoxide, a poisonous gas that can cause unconsciousness and death. It is an odorless and colorless gas formed during combustion of hydrocarbon fuels. Symptoms of carbon monoxide poisoning are:

0

0

0

Dizziness

Headache

0

0

Vomiting

Muscular Twitching

Weakness .and Sleepiness

0

Throbbing in Temples

If you experience any of these symptoms, get out into fresh air immediately, shut down the unit and do not use until it has been inspected.

The best protection against carbon monoxide inhalation is proper installation and regular, frequent inspections of the complete exhaust system. If you notice a change in the sound or appearance of exhaust system, shut the unit down immediately and have it inspected and repaired at once by a competent mechanic.

Cooling

System

0

Coolants under pressure havea higher boiling point than water. DO NOT open a radiator pressure cap when coolant temperature is above 212OF (lOO°C) or while engine is running.

Keep the

Unit and Surrounding Area Clean

0

Make sure that oily rags are not lefl on or near the engine

0

Remove all unnecessary grease and oil from the unit.

Accumulated grease and oil can cause overheating and subsequent engine damage and present a potential fire by any means, is strictly prohibited.

hazard.

E-6

a

Table of Contents

TITLE PAGE

General Information

Specifications

.................................................

1-1

......................................................

2-1

Dimensions and Clearances

..........................................

3-1

Assembly Torques and Special Tools

Engine Troubleshooting

Oil System

Fuel System

........................................................

7-1

Ignition and Battery Charging

Starting

System

.................................

4-1

.............................................

..........................................................

6-1

........................................

8-1

.....................................................

Engine Disassembly

9-1

................................................

10-1

I

AWARNING

1

EXHAUST GAS IS DEADLY!

Exhaust gases from all fuels (including diesel, gasoline, liquid prop ne, natural gas) contain carbon monoxide, an odorless and colorless gas. Carbon monoxide is poisonous and can cause unconsciousness and death. Symptoms of carbon monoxide poisoning can include:

0

0

0

Dizziness

Nausea

Headache

Weakness and Sleepiness

0

0

Throbbing in Temples

Muscular Twitching

Vomiting

Inabirity to Think Coherently

IF YOU OR ANYONE ELSE EXPERIENCEANY OF THESE SYMPTOMS, GET OUT

INTO

THE FRESH AIR

IMMEDIATELY. If symptoms persist, seek medical atfention. Shut down the unit and

do

not operate untilit has been inspected and repaired.

Protection against carbon monoxide inhalation includes proper installation, ventilation and regular, frequent visual and audible inspections

of

the complete exhaust system.

Redistribution or publication of this document, by any means, is strictly prohibited.

i


General Information

*

.

INTRODUCTION

This manual deals with specific mechanical and electrical information needed by engine mechanics for troubleshooting, servicing, repairing, or overhauling the engine.

Use the separate PARTS MANUALfor parts identification and for establishing their proper location on assemblies.

The PARTS MANUAL contains detailed exploded views of each assembly and the individual piece part numbers and their proper names for ordering replacement parts.

The illustrations and procedures presented in each section apply to the engines listed on the cover. The flywheel-blower end of the engine is the front end

so

right and left sides are determined by viewing the engine from the front. The No.

1

cylinder is on the left, No. 2 cylinder is on the right.

If

a major repair or an overhaul is necessary, acompetent mechanic should either do the job or supervise and check the work of the mechanic assigned to the job to ensure that all dimensions, clearances and torque values are within the specified tolerances.

Use the table of contents for a quick reference to the separate engine system sections.

The troubleshooting guide is provided as a quick reference for locating and correcting engine trouble.

The wiring diagram shows how the electrical components are interconnected.

The disassembly section contains major overhaul procedures for step by step removal, disassembly, inspection, repair, and assembly of the engine components.

Use only Genuine Onan replacement parts

to

ensure quality and the best possible repair and overhaul results. When ordering parts, always use the complete model and spec number as well as the serial number shown on the nameplate.

ENGINE

MODEL

REFERENCE

Identify your model

by

referring to the model and specification (spec letter) as shown on the unit nameplate. Always use these numbers and the engine serial number when making reference to your engine.

How to interpret

MODEL

and SPEC

NO.

B

48

G G A 0 2 0 1 1 D

TTTTTT T T

1 2 3 4 5 6

7 8

1. Factory code for general identification of basic engine series.

2. Cubic inch displacement.

3.

Engine duty cycle.

4. Fuel required (G=gasoline).

5. Cooling system description

(A=air-cooling-pressure).

6.

BHP rating.

7. Factory code for designated optional equipment, if any.

8. Specification (spec letter) which advances with

factory production modifications.

IAWARNING

i

INCORRECT SERVICE OR REPLACEMENT OF PARTS CAN RESULT IN

SEVERE PERSONAL INJURY AND/OR EQUIPMENT DAMAGE. SERVICE

PERSONNEL MUST BE QUALlFlED TO PERFORM ELECTRICAL AND/OR

MECHANICAL SERVICE.

1-1


,


a

Specifications

SPECIFICATION

Number

of

Cylinders

Bore

Stroke

Displacement

Compression Ratio

Rated Speed (Maximum)

Power at

Rated Speed

Oil

Capacity

Without Filter

Oil Filter Capacity

Crankshaft Rotation

(viewed from flywheel)

Valve Clearance (Cold)

Intake

Exhaust

Spark Plug Gap

Breaker Point Gap

-

Static

(Full Separation and Engine Cold)

Ignition Timing

This manual contains

SI

metric equivalents that follow immediately in parentheses after the

U.S.

customary units

of

measure.

Cylinder Compression

UNIT OF

MEASURE

in

(mm) in

(mm) cu in

(cm3)

RPM

BH P

(kW)

Qts

(I i

tre)

Qts

(litre) in

(mm) in

(mm) in

(rnm) in

(mm) in

BTC

BTC psi

(kPa)

B43E

2

3.250

(82.55)

2.620

(66.55)

43.3

6.2

to 1

3600

16

(1 1.9)

1.5

(1.4)

.3

(-3)

Clockwise

.005

.013

(.33)

.025

(.64)

.016

(.41)

75

16"

to

517 to

115

793

SERIES

8436

2

3.250

(82.55)

2.620

(66.55)

43.3

6.5

to

1

3600

18

(13.4)

1.5

(1

-4)

.3

(*3)

Clockwise

.005

.013

(.33)

.025

(.64)

.016

16"

75

to

115

517

to

793

B48G

2

3.250

(82.55)

2.875

(73.00)

47.7

(782)

7.0

to

1

3600

20

1.5

(1

-4)

.3

(-3)

Clockwise

.005

(.13)

.013

(.33)

.025

(.64)

Spec

A

& B

.020

(-53)

Begin Spec C

.016

Spec A & B

20"

Begin Spec C

16"

75

to

115

to

793


2-1


,

a

Dimensions and Clearances

All clearances given at room temperature

of

70°F.

"C).

in parentheses) unless otherwise specified.

DESCRIPTION

.

MINIMUM

Inches

(mm)

MAXIMUM

Inches

(mm)

CYLINDER BLOCK

Cylinder Bore Honed Diameter

...................................

Maximum Allowable

Taper

.........................................................

Out-of-Round

.................................................

Main Bearing Inside Diameter (Without bearing)

...................

Main Bearing Inside Diameter (Installed)

..........................

Camshaft Bearing Bore (Bearing installed)

........................

3.2490

2.187

2.0015

1.3760

(82.53) 3.2500

(55.55)

(50.84)

(34.95)

0.005

0.003

2.188

2.0040

1.3770

(82.55)

(0.08)

(55.58)

(50.90)

(34.98)

CRANKSHAFT

Main Bearing Journal Diameter..

Main Bearing Clearance..

.................................

1.9992

........................................

0.0025

Connecting Rod Journal Diameter..

Crankshaft End Play..

..............................

1.6252

...........................................

0.006

(50.78)

(0.064)

(41.28)

(0.15)

2.0000

0.0038

1.6260

0.01 2

(50.80)

(0.097)

(41.30)

(0.30)

CONNECTING ROD

Large Bore Diameter (Rod bolts properly torqued)

Connecting Rod Side Clearance..

.................

................................

Piston Pin Bushing Bore (Finished bore)

..........................

1.6280

0.0020

0.6879

Bearing to Crankshaft Clearance

Aluminum Rod

................................................

0.0020

(41.35)

(0.051)

(17.47)

1.6285

0.01 60

0.6882

(0.051)

0.0033

(0.406)

(1 7.48)

(0.084)

CAMSHAFT

Bearing Journal Diameter..

Bearing Clearance..

End Play.

Camshaft Lift

......................................

.............................................

1.3740

0.0015

.......................................................

0.0030

B43E

...................................................

.........................................................

(34.90)

(0.038)

(0.076)

1.3745

0.0030

0.300

(7.62)

0.258

(6.55)

(0.076

PISTON

Clearance in Cylinder

Measure

90"

to pin

1.187

inch below top of piston

...............

0.0033

Piston Pin Bore..

................................................

0.68774

Ring Groove Width

Top

No.

1

Compression Ring..

2

Compression Ring.

.....................................

......................................

No.

3

0.080

0.080

(0.084)

(1

7.47)

(2.032)

(2.0321

0.0053

0.68814

0.081

0.081

(0.135)

(17.48)

(2.057)

12.057)

.........................................

0.188 i4.775j 0.189 i4.801 j

3- 1


DESCRIPTION

MINIMUM

Inches (mm)

MAXIMUM

Inches (mm)

PISTON PIN

Clearance in Piston

..............................................

Clearance in Connecting Rod

Aluminum Rod

Diameter

................................................

........................................................

0.00004 (0.001 0) 0.00064 (0.01 62)

0.0002

(0.005) 0.0007

(0.01 8)

0.6875 (17.46) 0.6877

(17.47)

PISTON RINGS

Clearance

Top Groove

...................................................

Ring End Gap in Cylinder

........................................

INTAKE VALVE

Stem Diameter

..................................................

Clearance (Stem to Guide)

Valve Face Angle

.......................................

................................................

0.003

(0.076)

0.010 (0.254)

0.008 (0.203)

0.020 (0.508)

0.3425 (8.70) 0.3430 (8.71)

0.0010 (0.025) 0.0025 (0.064)

44"

INTAKE VALVE SEAT

Seat Bore Diameter

.............................................

Seat Outside Diameter

Valve Seat Width

Valve Seat Angle

...........................................

................................................

................................................

1.4395

(36.56)

1.443

(36.65)

0.031 (0.787)

45"

1.4405 (36.59)

1.444 (36.67)

0.047 (1.194)

EXHAUST VALVE

Stem Diameter

..................................................

Clearance (Stem to Guide)

.......................................

Valve Face Angle

................................................

0.3410 (8.661) 0.3415 (8.674)

0.0025 (0.064)

44"

0.040 (0.102)

EXHAUST VALVE SEAT

Seat Bore Diameter

..............................................

Seat Outside Diameter

...........................................

Valve Seat Width

Valve Seat Angle

................................................

................................................

1.1 89 (30.20)

1.192 (30.28)

0.031

(0.787)

4 5 O

1.190 (30.23)

1.193 (30.30)

0.047

(1.1 94)

VALVE GUIDE

Inside Diameter

.................................................

TAPPET

Body Diameter

Bore Diameter

..................................................

...................................................

Clearance in Bore

...............................................

VALVE SPRINGS INTAKE AND EXHAUST

Valve Spring Free Length (Approx.)

..............................

Valve Spring Length

Valve Open

....................................................

Valve Closed

..................................................

Spring Load @I 1.375 inch (Valve Closed)

..........................

Spring Load @ 1.125 inch (Valve Open)

...........................

0.344 (8.74) 0.346 (8.79)

0.7475 (18.99) 0.7480 (19.00)

0.7505 (1 9.06)

0.0015 (0.038)

0.751 5

0.003

(1 9.09)

(0.076)

1.662 (42.21

)

1.1 25 (28.58)

38

Ib

1.375 (34.93)

.

(17 kg)

42

Ib

.

(19 kg)

71

Ib

.

(32

kg)

79

Ib

.

(36 kg)

GEAR BACKLASH

Timing Gear

.....................................................

Oil Pump Gear

..................................................

GOVERNOR

Dashpot to Governor Arm Bracket

................................

0.001

(0.025)

0.002

(0.051)

0.040 (1.02)

0.006

0.005

(0.152)

(0.127)

0.060 (1.52)

c


3-2

Assembly Torques

1

.

The torque values given in Table 1 have been determined for the specific applications. Standard torque values must not be used where those listed in Table

1

apply. The engine assembly torques given here will assure proper tightness without danger

of

stripping threads. All threads must be clean and lubricated with new engine oil before torquing.

Check all studs, nuts, and capscrews, and tighten as required to keep them from working loose. Refer to the PARTS MANUAL for the location of washers and capscrews.

TABLE

1.

DESCRIPTION

TORQUE

SPECIFICATION

Gearcase Cover

Ft.-Lb. Nm

...............

8-1

0 11-14

Cylinder Head Bolts (Cold)

............

16-18 22-24 Asbestos Gasket

Graphoil Gasket

.............

Rear Bearing Plate Screws

Starter Mounting Bolts

Connecting Rod Bolt..

Flywheel Cap Screw..

.....

25-27 34-37

.........

24-26 33-35

.........

14-1 6

14

19-22

19

.........

50-55 68-75

Oil Base

......................

18-23 24-31

DESCRl PTl ON

TORQUE

SPECIFICATION

FLLb. Nm

Intake Manifold Mounting

Screws..

Oil Pump

Valve Cover.

...................

6-10

8-1 4

.....................

Exhaust Manifold Mounting

7-9

..................

1-2

10-1 2

1-3

Screws

.....................

6-10

8-1 4

Other 1 /4" Cylinder Block

Stud and Nuts..

.............

7-9

10-1 2

Other 511 6" Cylinder Block

Stud and Nuts..

.............

8-10 11-14

Special Tools

.

The following special

tools

are available from

Onan. For further information see TOOL CATALOG

900-0079.

Valve Seat Driver

Valve Guide Driver

Oil

Seal Guide and Driver

Combination Bearing Remover (Main and Cam)

Combination Bearing Driver (Main and Cam)

Flywheel Puller

4-1



Engine

Troubleshooting

GASOLINE

ENGINE

TROU

BLES HOOTlN

G

5-1



C

Oil System

1

I

CRANKCASE OIL

Refer

to

Periodic Maintenance Schedule (located in the

Operator's Manual) for oil change interval. If operating in extremely dusty, high ambient, or low ambient conditions, change oil more often.

Hot crankcase oil can cause burns if it comes in contact with skin. Wear protective clothing and keep fingers and hands clear when draining oil.

(BCAUTION]

Excess oil can cause high oil consumption, high operating temperatures, and oil foaming.

Do

not overfill crankcase.

Run engine until thoroughly warm before draining oil.

Stop the engine, place a pan under the drain outlet and remove the oil drain plug. After the oil is completely drained, clean and replace thedrain plug. Fill crankcase with correct amount

of

oil. Refer to SP€C/NCAT/ONSfor crankcase capacity. Use oils meeting the

API classi-

fication SF, SF/CC, or SF/CD. Refer to chart to determine the proper viscosity grade of oil to use. Straight weight

oils

are recommended for severe duty use and at temperatures above 32OF

( O O C )

for minimum oil consumption.

Crankcase pressure can blow out hot

llEGE%l

oil,

which can cause severe personal injury.

Do

not check oil while fhe engine

is

running.

Oil level should be to the FULL mark of the dipstick. Start engine and run for a short time to check for oil leaks around the drain plug.

F -20

c 3 0

0

-lo

-io

20

b

40

10

60

i 0

80

3b

100

40

TEMPERATURE RANGE YOU EXPECT BEFORE NEXT OIL

CHANGE

LS-1170

ALWAYS REPLACE

TIGHTLY OR OIL

LEAKAGE MAY OCCUR

I

COOLING FINS

CAUTION

-

DO

NOT OVERFILL

1

(0.5 litre)

c-1000

FIGURE

1. CRANKCASE OIL FILL

6-1

c-1001

FIGURE

2. OIL

FILTER


OIL FILTER CHANGE

Refer to Periodic Maintenance Schedule, located in the

Operator’s Manual, for oil filter change interval. If operating in extremely dusty, high ambient, or low ambient conditions change oil more often.

Spin off oil filter element and discard it.

Thoroughly clean filter mounting surface and install new element, making sure new gasket is inserted in the element.

Apply a thin film of

oil

to the gasket. Spin element down by hand until gasket just touches mounting pad and then turn down an additional overtighten.

With oil in crankcase, start engine and check for leaks around filter element. Retighten only as much as necessary to eliminate leaks; do not overtighten.

CRANKCASEBREATHER

Refer to Periodic Maintenance Schedule, located in the

Operator’s Manual, for crankcase breather service interval. Service sooner if crankcase becomes pres- surized as evidenced by oil leaks at the seals or excessive oil in the air cleaner housing.

Most parts cleaning solvents are flammable and can cause severe personal injury or death if used improperly. Follow the manufacturer’s recommendations when cleaning parts.

Remove the breather tube from the valve cover (Figure

3).

Remove the pack, capscrew, flatwasher, valve cover and gasket, spring, flatwasher, reed valve, and breather baffle. Discard gasket and clean all parts in parts cleaning solvent.

=

cause engine damage. Do not overtighten valve cover.

The reed valve must be flat with no sign of a crease.

Assemble using a new gasket. Torque capscrew to 1-2 ft-lbs (1 -3 Nm).

FIGURE

3.

CRANKCASE BREATHER c-low

.

6-2


*

.

.

PRESSURE LUBRICATION

All

engines

use

an

oil

pump

to

provide

a

constant

flow

ofoil to theengine parts.Theoil supply collect sin the oil base where it is picked up by the oil pump pick-up cup.

A

by-pass valve is

used

to control

oil

pressure.

Drain oil before removing oil base and always use a new gasket when replacing the oil base.

Oil Pump

The oil pump (Figure 4) is mounted behind the gear cover and is driven by the crankshaft gear. Inlet pipe and screen assembly are attached directly to the pump body.

A

discharge passage in pump cover registers with a drilled passage in the crankcase.

Parallel passages distribute oil to the front main bearing, rear main bearing, and pressure control bypass valve.

Check oil pump thoroughly for worn parts.

Oil pump to prime it before reinstalling. Exceptfor gaskets and pick-up cup, component parts

of

the pump are not available individually. Install a new pump assembly

if

any parts are worn.

Oil By-Pass

Valve

The by-pass valve (located t o the right and behind gear cover), controls oil pressure by allowing excess oil to flow directly back to the crankcase. Normally the valve begins to open about 20 psi (138 kPa).

The valve is non-adjustable and normally does not need maintenance. Determine if valve is operating normally by inspecting plunger action as follows:

1. Remove the 3/8 x 24 x 7/8 cap screw located behind gear cover and under governor arm.

2. Remove spring and plunger with a magnet tool.

OIL

PUMP PICK-UP CUP

OIL

PUMP ASSEMBLY

CRANKCASE TURNED

ON LEFT SIDE

FIGURE 4.

OIL PUMP ASSEMBLY

Ls-iiog

3. Determine proper valve operation by checking the spring and plunger according to the following measurements.

Plunger Diameter.,

........

0.3105 to 0.3125 in.

(7.89 to 7.94 mm)

Spring

Free Length..

Load

...........

1.00 inch (25.4 mm)

............

2.6

f

& 0.9 N) when compressed to 0.5 inch (12.7 mm)

4.

Check the valve seat and clean away any accumulation of metal particles which could cause erratic valve action. Verify that the valve seat is not damaged.

5. Clean plunger and spring in parts cleaning solvent and install.

Circumferential grooves in the main bearings supply oil to connecting rod bearings through drilled passages from each main journal. A drilled passage connects the front main bearing oil supply to the front camshaft bearing; rear cam bearing is splash lubricated. Oil overflow from the bypass valve furnishings lubrication to the camshaft drive gears.

Normal oil pressure should be 30 psi (207 kPa) or higher when the engine is at normal operating temperature. If pressure drops below this value at governed speed, inspect oil system for faulty components.



Fuel System

,

CARBURETOR

Most carburetors have a fixed main jet. An optional main fuel adjustment kit (altitude compensation kit) is available.

The carburetor idle mixture was set for maximum efficiency at the factory and should normally not be disturbed.

If

adjustments seem necessary, first be sure the ignition system is working properly and governor sensitivity is properly adjusted.

If adjustment is needed, refer to Figures 1 and 2 and

proceed as follows:

I ]

Overfightening the mixfure adjustment screw will cause carburetor damage.

Turn mixture adjustment screw in

on/y

until

light tension can be felt.

1.

Walbro carburetor mixture screw settings:

Turn both mixture screws in until lightly seated, then back the idle mixture screw out 1-1 /8 turns and the main mixture screw out 1-1

/2

Nikki

full

adjustment carburetor mixture screw settings:

Turn idle mixture screw in until lightly seated, then back idle mixture screw out 1-1 /4 turn. On engines equipped with optional main fuel adjustment, turn main mixture screw in until lightly seated then back the main mixture screw out as specified below.

B43E

B43G

1-1

14

to 1-1

/2

B48G

1

- 5 / 8

to 1-718 turns

Nikki limited idle adjustment carburetor mixture screw settings:

The carburetor has a limited idle adjustment range between stops of *1/8 turn. The screw should only be adjusted within these limits; in to lean the mixture, out to richen. There is no main mixture adjustment.

When replacing the idle mixture screw, turn until lightly seated, then turn back idle mixture screw out

1-1 /4 turn. Replace the limiter cap with the plastic stop approximately centered.

LOW SPEED

_ _ - -

SIDE PULL GOVERNOR ASSEMBLY

FRONT PULL GOVERNOR ASSEMBLY

FIGURE 1. GOVERNOR SPEED ADJUSTMENT


7-1

2.

Start the engine and allow it to warm up thoroughly (at least 10 minutes).

\

Some equipment manufacturers may require higher throttle stop speed and governor low speed rpm settings. Referto equipment manufacturer’s Operators Manual for the correct rpm settings. When rpm settings are not specified by the equipment manufacturer, use the rpm settings listed in Steps

3 &

5.

3.

Move the engine speed control to the slow position. Bend or turn the low speed stop on the governor so that the throttle stop screw on the carburetor controls enginespeed. Adjust the throttle stop screw for 1000 rpm idle.

ADJUSTMENT

WALBRO CARBURETOR

FS-1002

4.

Determine the best idle mixture setting by first turning the idle adjustment screw in until engine speed drops and then outward until engine speed drops again. Over a narrow range between these two settings, engine speed remains at its highest.

Set the adjustment screw about 1 / 8 turn outward

(rich) from the midpoint of this range. On Nikki limited adjustment idle mixture carburetor adjustments are limited to these limits.

THROTTLE

SZEw

\

IDLE FUEL

ADJUSTMENT

NlKKl CARBURETOR

LOCATION

OF

OPTIONAL MAIN

FUEL ADJUSTMENT

FS-1406

5. Readjust the throttlestop screw for

1000 rpm idle, then adjust the governor low speed stop for 1100 rpm idle.

.

6. Move the engine speed control

to the fast position. Bend the high speed stop on the governor so the engine runs at the equipment manufacturer’s recommended speed.

7.

Checkthe main mixtureadjustment (if so equipped) by rapidly accelerating the engine from idle to full speed. The engine should accelerate evenly and without hesitation. If it does not. turn the main adjustment screw out in 1

/8

the engine accelerates smoothly, but do not turn it out more than

1

/2

7-2

NlKKl CARBURETOR WITH SEMI-AUTOMATIC CHOKE

AND LIMITED IDLE

MIXTURE

SCREW.

FS-1406-2

FIGURE

2.

CARBURETOR ADJUSTMENTS


CHOKE PLATE

CARBURETOR OVERHAUL

Carburetion problems that are not corrected

by

mixture adjustments are usually a result of gummed- up fuel passages or worn internal parts. The most effective solution is a complete carburetor overhaul.

In general, overhauling a carburetor consists of complete disassembly, a thorough cleaning, and replacement

of

worn parts. Carburetor repair parts are available.

General instructions for overhauling a carburetor are given below. Carefully note the position of all parts while removing to assure correct placement when reassembling. Read through all the instructions before beginning for a better understanding of the procedures involved. Carburetor components are shown

in Figure

3.

-1

/snition of fuel can resulf in severe personal injury or death. Do not smoke or allow any spark, pilot light, or arcing equipment near the fuel system.

CHOKE SHAFT

THROTTLE STOP

SCREW

-*

IDLE ADJUSTME

HROTTLE PLATE

WALBRO CARBURETOR

CHOKEPLATE

D

t

CHOKE SHAFT

a

/-

.

.

FLOAT ASSEMBLY

FLOAT ASSEMBLY

FIXED

OPTIONAL MAIN

FUEL ADJUSTMENT

\

CAP

FS-1440-3

-

!

'THROTTLE PLATE

9 b

NlKKl CARBURETOR NlKKl CARBURETOR WITH SEMI-AUTOMATIC CHOKE

AND LIMITED IDLE MIXTURE SCREW.

FIGURE 3. CARBURETOR ASSEMBLY

7-3

FS-1440


Removal

1.

Remove air cleaner and hose.

2. Disconnect governor and throttle linkage, choke control and fuel line from carburetor.

3. Remove the four intake manifold cap screwsand lift complete manifold assembly from engine.

4.

Remove carburetor from intake manifold.

Disassembly (Walbro and Nikki)

1.

Remove throttle and choke plate retaining screws, then plates.

Pull

out throttle and choke shafts.

2.

Remove main jet and idle adjustment needle.

3.

Remove attaching screws and separate upper and lower carburetor sections.

4.

Carefully note position of float assembly parts, then pull out retaining pin and float assembly.

5. Remove needle and unscrew needle valve seat.

Disassembly (Nikki limited idle mixture)

1.

Remove main jet and idle adjustment needle.

2.

Remove attaching screws and separate upper and lower carburetor sections.

3. Carefully note position of float assembly parts, then pull out retaining pin and float assembly.

4. Remove needle valve.

Reassembly and Installation (Walbro and Nikki)

1.

Install needle valve and seat, main jet and float assembly. Make sure that float pivot pin is properly placed and that the float moves freely without binding.

2. Gently push float tang down until needle just seats;

measure float level as shown in Figure 4. Adjust

float level if necessary. Release float tang and

measure float drop as shown in Figure

4

(the distance from top of carburetor body to top of float).

3.

Position gasket on lower carburetor section and install upper carburetor section.

4. Slide in throttle shaft and install plate using new

screws. Before tightening the screws, the plate must be centered in the bore.

To

do

so, back off

the throttle stop screw as necessary and completely close the throttle lever. Seat the plate by tapping with a small screwdriver, then tighten screws. Install the choke shaft and plate in the same manner.

5. Install idle adjustment screw, throttle stop screw, and fixed main jet plug or optional main fuel adjustment needle.

6.

Mount carburetor on intake manifold and install assembly on engine.

7. Mount air cleaner assembly. Connect air intake hose, breather hose, fuel line, vacuum line, and throttle linkage.

8.

Adjust carburetor and governor according to directions given in this section.

Cleaning and Repair

1.

Soak all metal components not replaced in carburetor cleaner. Do not soak non-metal floats or other non-metal parts. Follow the cleaning manufacturer’s recommendations.

2.

Clean all carbon from the carburetor bore, especially where the throttle and choke plates seat. Be careful not

to

plug the idle or main fuel ports.

3.

Dry out all passages with low pressure air (35 PSI).

Avoid using wire or other objects for cleaning that may increase the size of critical passages.

4.

Check the condition of adjustment needle. Replace if damaged. Replace float if loaded with fuel or damaged.

5. Check the choke and throttle shafts for excessive play in their bore. This condition may necessitate replacement of the carburetor.

6.

Replace

old

components with new parts.

7-4

Reassembly and Installation (Nikki limited idle mixture)

1. Install needle valve, main jet, and float assembly.

Make sure float pivot pin is properly placed and float moves freely without binding.

2. Turn carburetor on its side and measure float level

(Figure 4). Adjust float level only if necessary.

Measure float drop (the distance from the top of carburetor body to top of float). Adjust only if necessary.

3. Position gasket on lower carburetor section and install upper carburetor section.

4. Install idle adjustment screw, throttle stop screw,

and fixed main jet plug.

5.

Mount carburetor on intake manifold and install assembly on engine.

6.

Mount air cleaner assembly. Connect air intake hose, breather hose, fuel line, vacuum line, and throttle linkage.

7.

Adjust carburetor and governor according to directions given in this section.


1

BEND FLOAT

TAB HERE

TO ADJUST

0.02kO.02 INCH

FUEL LEVEL

0.25 INCH

I

MINIMUM

FLOAT

DROP

I

0.20lNCH

BEND FLOAT ARM

HERETO ADJUST

/

RBURETOR

AND SEAT

FLOAT LEVEL ADJUSTMENT WITH FUEL NO FUEL

FLOAT DROP ADJUSTMENTS

When checklng float level and float drop measure to float body, not seam.

FS-1524

WALBRO FLOAT LEVEL ADJUSTMENT

BEND FLOAT 0.028"k0.028"

TANG HERE (0.712k0.712 rnrn)

FUEL LEVEL

MINIMUM

FLOAT DROP

mm)

~

N E ~ D L E

AND SEAT

FLOAT LEVEL ADJUSTMENT

NEEDLE

AND SEAT

BEND FLOAT

~N~~~~~

BEND FLOAT ARM

HERE TO ADJUST

WITH FUEL

NO

FUEL


When checking float level and float drop measure to float body, not seam.

FS-1689

NiKKl FLOAT LEVEL ADJUSTMENT

BEND FLOAT ARM

HERE TO ADJUST

MINIMUM

V

u

FLOAT LEVEL ADJUSTMENT

I

WITH FUEL NO FUEL


When checking lloat level and float drop measure to float body, not seam.

NlKKl FLOAT LEVEL ADJUSTMENT WITH SEMI-AUTOMATIC

CHOKE AND LIMITED IDLE MIXTURE SCREW.

I

FS-1683

Redistribution or publication of this document,

FIGURE 4. CARBURETOR FLOAT LEVEL ADJUSTMENTS

by any means, is strictly prohibited.

7-5

PULSATING-DIAPHRAGM FUEL PUMP

Pulsating diaphragm fuel pumps, or pulse pumps, rely on changes in crankcase vacuum to create a pulsating movement of the pump diaphragm.

As the engine’s

pistons move outward, a vacuum is created. This vacuum is transmitted to the pump diaphragm, causing it to pull back and suck fuel into the pump. As the engine’s pistons move inward, crankcase vacuum is reduced and the diaphragm return spring pushes the pump diaphragm forward, forcing fuel through the pump outlet.

Fuel Pump

Test Procedure

Before testing make certain that fuel pump vacuum line connections are tight and free of leaks.

1. Operate engine at an idle for five minutes to ensure that carburetor is full of fuel.

2. Shut engine off and remove fuel inlet line from fuel

Pump.

7

Ignition of fuel can result in severe personal injury or death.

Thoroughly clean up any spilled fuei

3. Connect a vacuum gauge tofuel pump inlet using a piece of fuel hose with clamps.

4.

Start engine and allow to idle for five seconds.

Record vacuum gauge reading.

5. Move throttle control to high idle position. Wait five seconds and record vacuum gauge reading.

6.

off and remove vacuum gauge hose from fuel pump inlet. Connect fuel inlet line to fuel pump.

7.

Remove fuel outlet line from fuel pump.

-1

Ignition of fuel can result in severe personal iniurv or death.

Thoroughly clean up any spilled fuei

8.

Connect a pressure gauge tofuel pump outlet using a piece of fuel hose with clamps.

9.

Start engineand allow to idle for five seconds. While holding pressure gauge level with pump outlet record pressure gauge reading.

10.

Move throttle control to high idle position and allow engine to run for five seconds. While holding pressure gauge level with pump outlet record pressure gauge reading.

11.

Shut engine off and remove pressure gauge hose from fuel pump outlet. Connect fuel outlet line to fuel pump.

Repair or replace the fuel pump if test readings are not within the values specified

in

TABLE 1.

TABLE

1

PULSE PUMP TEST SPECIFICATIONS

Engine

Speed

Low

Idle

High Idle

Pump Inlet

Vacuum

(Minimum)

2.6 inches of mercury of mercury

Pump Outlet

Pressure

(Minimum)

1.7 psi

1.7 psi

Fuel Pump Repair

This section applies only to Facet fuel pump. The Nikki fuel pump is not repairable; replace unit if test readings

are not within the values specified in Table 1.

1. Remove thevacuum and fuel lines. Inspect the lines for wear, cracking or brittleness. Replace as necessary.

2. To insure correct alignment when reassembling, scribe a line across the outer pump parts on each end of the pump.

3.

Holding the pump carefully, remove the assembly screws (Figure

5.)

4.

Carefully pull apart the pump sections and check for worn or damaged parts. Install pump repair kit.

5. Check and unclog

if necessary the small diaphragm air bleed hole located behind the pump diaphragm in the pump base.

ACAUTION

A clogged diaphragm air bleed hole can cause diaphragm wear and seal damage. Be sure air bleed hole

i s

unclogged.

I

6. Replace gaskets and reassemble pump. Reinstall assembly screws, checking the scribe marks for proper alignment. Reinstall fuel and vacuum lines and clamps.

[-

Improper fuel pump

parts align-

ment or misconnected fuel lines can result in leaking fuel, creafing a serious fire hazard. Use extreme care when reassembling and reinstalling fuel pump.

I

1


7-6

PUMP

COVER

\

GASKET

\

*

L

I

ASSEMBLY SCREWS

REED

VALVE

FIGURE 5. EXPLODED VIEW OF FACET FUEL PUMP

AIR CLEANER

(BCAUTIONI

A dirty air cleaner element can cause engine damage. Ensure air cleaner element

is

kept clean and free of excess debris.

Engine is equipped with a paper element. If the engine is equipped with polyurethane precleaner, it must be removed, cleaned and oiled every

25

hours

of

operation, or more under extremely dusty conditions.

1.

To clean precleaner wash in water and detergent,

refer to Figure 6. Remove excess water by squeezing

like a sponge, and allow to dry thoroughly.

FS-1684

Distribute one tablespoon

of

SAE 30 engine oil evenly around the precleaner. Knead into precleaner and wring out excess oil.

2. Depending on conditions in which the engine is operating, the inner paper element should be replaced whenever it becomes excessively dirty or oily.

ACAUT~ON

D

engine damage.

Do not run engine without air cleaner element installed.

1.

WASH

2. SQUEEZE DRY

3.

COAT WITH OIL

4.

INSTALL OVER PAPER ELE

WRAPPER

FS-1131

FIGURE 6. AIR CLEANER ASSEMBLY

7-7


DASHPOT

GOVERNOR

ARM BRACKET

0.050 INCH

(1.27

m m )

STOP

FIGURE 7.

DASHPOT CLEARANCE

DASHPOT ADJUSTMENT

1.

Pull governor arm and linkage (away from carburetor) until throttle stop contacts throttle stop screw.

2. Holding throttle against throttle stop screw, adjust dashpot to obtain

0.050 inch (1.27 mm) clearance

(Figure

7.)

3. Secure dashpot to air cleaner support bracket with hex nut provided. a

held with pliers.

if

Do not use p/iers when securing dashpot.

GOVERNOR SENSITIVITY

These engines are adapted for use where

a

wide range

of

speed settings is desired (Figure

8).

Engine speed

is

controlled at any given point between minimum and maximum by simply shifting the throttle lever on the dash panel until the desired speed is reached.

The fixed and variable speed governor give an automatic decrease in sensitivity when the speed is increased. The result is

good

stability at all speeds.

A

reliable instrument for checking engine speed is required

for

accurate governor adjustment. Engine speed can be checked with a tachometer.


7

-8

I

.

Check the governor arm, linkage, throttle shaft, and

lever for binding

condition

or excessive

slack and

wear at

connecting points.

A binding condition

at any point will cause the governor to act slowly and regulation will be poor. Excessive looseness may cause a hunting condition and regulation could be erratic.

Work the arm back and forth several times by hand while the engine is idling to check for above conditions.

3.

Holding linkage and governor arm toward direction

of

carburetor, insert end

of

linkage into which-

ever hole (C) in

governorarm

lines up the

closest.

If between two holes, insert in next hole out.

If the governor is hunting or not operating properly,

adjust as

follows

(Figure

8).

On side pull governors the governor spring is set by the factory

in

the third hole

of

the governor arm.

(Third hole from pivot). On front pull governors the governor spring

is

set by the factory in the second hole of the governor arm adapter. (Second hole from pivot.)

To increase sensitivity, move spring loop into a hole closer to the pivot. To decrease sensitivity, move spring loop into a hole farther away from the pivot. After sensitivity has been set, recheck the low speed rpm setting. Adjust if necessary.

1.

Disconnect linkage (A) from one of holes

(C).

2.

Push linkage

(A)

(B) as far back

(toward carburetor) as they will go. s1

THROTTLE STOP)

SCREW

@

GOVERNOR CONTROL

GOVERNOR SPRING GOVERNOR

.

SHAFT YOKE

SIDE

PULL GOVERNOR

THROTTLE S T O q

THROTTLE PLATE

@

GOVERNOR CONTROL

LINKAGE

GOVEkNOR SPRING

FRONT PULL GOVERNOR

FIGURE 8. VARIABLE SPEED GOVERNOR

ADJUSTMENTS

7-9



Ignition and Battery Charging

I

I

G

N IT1 0 N

SYSTEM D

ON

The engine is equipped with an automotive type battery ignition system. Both spark plugs fire simultaneously,

thus

the need for

a

distributor

is

eliminated.

IGNITION TIMING

Thetiming is preset at thefactory. Slight timing changes can be made by adjusting the point gap.

BREAKER POINTS

The timing is adjusted to specification during initial engine assembly and is fixed by the point gap adjustment. To maintain maximum engine efficiency, change the breaker points as recommended in the Periodic

Maintenance Schedule.

Replacement and Adjustment

1. Remove spark plugs.

2.

Remove breaker box cover. Rotatecrankshaftclock- wise (facing flywheel) until points are fully open.

3.

Remove condenser (screw A) and detach condenser lead and coil lead (screw

6). Engines with con-

densers mounted on the air cleaner bracket

do

not need to be removed unless being replaced.

4. Remove two Allen screws (C) and lift breaker

assembly from engine.

5. Replace condenser and point assembly with new

parts and reinstall using above procedure in reverse order of removal.

6.

Adjust point gap by rotating crankshaft clockwise

(facing flywheel) by hand until the points are fully open. Set the point gap (using flat feeler gauge) to gap specified in Sf€ClFlCATlONS by adjusting the

Allen screw (D) inward or outward (Figure 1). A.016 point gap is equivalent to 16" BTC.A.020 inch point gap is equivalent to 20" BTC. Make sure feeler gauge

is

clean and free

of

any grease, oil, or dirt.

POINTGAP

,.

W

FIGURE

1.

SETTING POINT GAP

7.

Replace breaker box cover, coil wire, spark plugs, and spark plug cables.

Timing Test

As a check for proper ignition timing

a

continuity test may be performed:

1.

Adjust breaker points.

2.

Remove blower housing

to

expose timing marks on top

of

gearcase cover and flywheel (Figure

2).

YWHEELTIMING

(TC) MARK

M-1397

FIGURE

2.

TIMING MARKS

3. Rotate flywheel clockwise until timing mark

is

aligned with the proper number of timing degrees

(Figure

2)

stamped on the top of gearcase cover.

Refer to

SPEClFlCATlONS

for proper number of timing degrees.

4.

Connect an ohmmeter or a continuity test lamp set across the ignition breaker points. Touch one test prod to the coil lead terminal (screw

B,

5. Touch the other test prod to a good ground on the

engine.

6.

Turn crankshaft against rotation (counterclockwise) until the points close. Then slowly turn the crankshaft with rotation (clockwise).

7.

The lamp should go out or continuity lost just as the points break which is where ignition occurs. if timing is early (advanced) the point gap is too large.

If

timing is late (retarded) the point gap is too small.

Adjust point gap accordingly.


IGNITION COIL

To

test primary and secondary windings within the ignition coil proceed as follows:

Use a Simpson 260 VOM or equivalent

Place black lead on ground (-)terminal of coil and red lead to positive (+)terminal. Primary resistance should read 3.87

-

4.73 ohms.

Change resistance setting on ohmmeter. Place ohmmeter leads inside of spark plug cable holes

(Figure 3). Secondary resistanceshould read 12,600

-

15,400 ohms.

If any of the above conditions are not met, replace coil. Refer to

PARTS CATALOG for correct part number.

BATTERY INSPECTION

Check battery cells with a hydrometer. The specific gravity reading should be approximately 1.260 at 77OF

(25"C), Figure

5.

If one or more cells are low on water, add distilled water and recharge. Keep the battery case clean and dry. An accumulation

of

moisture will lead to a more rapid discharge and battery failure.

Keep the battery terminals clean and tight. Push the cable terminal down flush with or slightly below the top of the battery post (Figure 6).After making connections, coat the terminals with a light application of petroleum jelly or grease to retard corrosion.

Poor contact at the battery cable connections

is

often a source of trouble. Make sure battery cables are in good condition and that contacting surfaces are clean and tightly connected.

Do

not reverse battery leads. Use recommended battery tools when disconnecting leads to avoid mechanical battery damage.

/Snition of explosive battery gases

can result in severe personal injury.

Do not smoke or allow any ignition

source

near the battery.

GRAVITY READING

SHOULD BE

1.260 at

77'F

(25OC)

1

FIGURE

3.

COILTEST

SPARK PLUGS

Check, and regap spark plugs as recommended in the

Periodic Maintenance Schedule (located in Operator's

Manual). Replace spark plugs that show signs of fouling or electrode erosion.

FIGURE 5. SPECIFIC GRAVITY TEST

BATTERY POST

f

CABLETERMINAL

FIGURE 4. SPARK PLUG GAP

8-2

FIGURE 6. BATTERY CABLE CONNECTION


L

1

BATTERY

JUMP STARTING

Occasionally, it may be

necessary

to jump

start (charge)

a

weak battery using

a

charged booster battery

to

start your engine. If jump starting is necessary, the following procedure is recommended in order to prevent starter damage, battery damage and personal injuries.

-1

Overcranking the engine can cause starter damage. Allow

5

minutes for starter to cool if engaged for longer than 30 seconds.

Disconnect engine load,

2. Use only a battery of the same voltage

(12V)

used with your engine.

3.

Attach one end of the positive booster cable(red) to the positive (+) terminal of the booster battery.

Attach the other end of the positive cable to the positive (+) terminal of your engine battery.

Attach one end of the negative (-) booster cable

(black) to negative (-) terminal of booster battery.

Attach other end of negative cable to a solid chassis ground on your engine.

-1

Electrical arcing can cause per- sonalinjury.

Do

not allowpositive and negative cable ends to touch.

Jump starting in any other manner may result in damage to the battery or the electrical system.

Turn ignition switch to

ON

to start engine. a

rectly can cause battery to

explode,

resulting

in

severe personal injury

or

death.

Do

not smoke or allow

any

ignition source near the battery, and do not jump start a frozen battery.

FLYWHEEL

ALTERNATOR

This unit is equipped with

a

permanent magnet flywheel alternator and solid-state voltage regualtor-rectifier

(output control). See Figure

7.

As

with all solid-state electrical units, precautions are necessary when servicing. Observe the following:

I

to run without being connected to the alternator will result in engine electrical system damage. Do not switch battery connections or allow engine to run without being connected to the alternator.

Weak ignition spark or a discharged battery indicates trouble in the charging system. But before testing the engine's charging system, always check the battery for serviceability.

Keep these points in mind when testing or servicing the flywheel alternator:

1.

Be sure engine is being run long enough and fast enough to recharge batteryafter each start. Charging system tests require afull charged battery. Alternator output is reduced in direct proportion to engine rpm.

Also, power required for accessories reduces power

available to recharge battery.

TO BATTERY

8-3


2. The regulator-rectifier has built in protection against open circuits or short circuits on the alternator output (B+) terminal. Either condition will cause the regulator-rectifier toshut off and appear as if it is not functioning. Prior to checking theregulator-rectifier, check all wiring between the regulator-rectifier B+ terminal and the battery positive (+) terminal to assure it is free of open circuits, resistances or short circuits. Also, if the battery is extremely discharged it may have insufficient power to “turn on” the regulator-rectifier.

3.

Be sure regulator-rectifier plug (connector) is inserted properly. Plug must bottom in receptacle; this eliminates any resistance due to a poor connection. Keep clean and tight.

4.

Make sure alternator stator leads are not shorted together.

5. Be sure regulator-rectifier has a good ground connection. Mating surface for mounting must be clean and fastener tightened properly.

6. Never reverse the battery leads.

With the engine between 1800 to 2600 rpm, observe the panel ammeter (if not already equipped, connect a test ammeter). If no charging is evident, proceed with the

Alternator Output Test.

ALTERNATOR OUTPUT TEST

Use a volt-ohmmeter, such as the Simpson 270, when testing the charging system.

1. With the engine running, check the battery terminal voltage (regulator output) using a DC voltmeter.

Voltage output should be within the values specified

in Table 1. If voltage is greater than specified

replace regulator-rectifier assembly. If voltage is less than specified, proceed to step 2.

2. Examineall wiresfor loose, corroded, broken connections, short circuits, etc. Check fuses. Repair as needed to assure complete circuits from regulator- rectifier B+ terminal to battery positive (+) terminal and from battery negative (-) terminal to regulator- rectifier case. If battery voltage remains low with engine running, proceed to step 3.

3. Disconnect plug from regulator-rectifier and test the AC voltage at the plug with engine running near

3600 rpm. If AC voltage reads more or less than specified in Table 1, proceed to step 4.

If

AC voltage is as specified but DC voltage is low, replace regulator-rectifier.

4.

Use the

R x l scale on the ohmmeter for detecting

opens in the stator (unit not running). Disconnect plug from regulator-rectifier. Connect ohmmeter test leads to wires coming from stator. Refer to

Table 1 for resistance specifications.

If resistance is not as specified, replace stator. If stator resistance readings are as specified and windings are not shorted to ground, low AC voltage may be due to

loss

of magnetism. If so, blower wheel assembly must be replaced. Check for magnetism with steel tool blade. Next, connect one ohmmeter test lead to stator wire, connect the other test lead to ground. If the ohmmeter reading is low the stator is grounded and must be replaced.

I

*

BASIC TEST

1. Battery

2.

Regulator

I

TABLE 1. TESTING 15- AND PO-AMPERE SYSTEMS

I

PROCEDURE

Battery Voltage

-

TEST

‘

15A. SYSTEM rLUES

20A. SYSTEM

12

VDC 12VDC

Battery Voltage after unit is running

3

to

5

minutes. 13.6 to

14.7

VDC

13.6 to 14.7 VDC

3. Alternator Stator and Wiring

.

Ohmmeter reading from stator output

-

Check at plug.

(4.

Alternator and Wiring

Measure

AC

open

circuit stator voltage with unit running. Measure between two stator leads with plug disconnected and unit running at approximately

3600 rprn.

0.1 to 0.2 Ohms

0.3 to

0.5

Ohms

I

40 VAC Minimum 31 VAC Minimum

.

60 VAC Maximum

51

VAC Maximum


8-4

ENGINE WIRING DIAGRAM

(Inertia

Type

Starter)

*

O

> u

2

'>

8.5


ENGINE WIRING DIAGRAM

(Solenoid

Shift

Type Starter)

f

a

U

w w

J

2

I

-.

i

w

p p

> n

“1

f

8-6

& +

W -


Starting

System

ELECTRIC STARTER

Normally the starter

will

require

little

or no service other than possible brush replacement. However,

if

through accident or misuse, the starter requires service or overhaul, the following information will provide the information necessary to perform this service.

1.

Remove both battery cables from battery. Discon- nect ground cable first.

2.

Disconnect battery cable and electrical lead wires from starter.

3.

Remove blower housing and cylinder air housing.

4.

Remove flywheel and starter motor.

Service

When starting engine, note starter motor action. The pinion gear should mesh quickly with flywheel ring gear and spin engine. Once engine starts and solenoid opens, the starter should disengage and stop. If starter cranks engine slow, or not at all, check start circuit components. Failure to crank is normally caused by low battery charge, defective battery cables, corroded or poor connections, or

low

temperatures.

If

after checking these variables, starter continues to crank slowly, starter must be removed and repaired.

Starter Disassembly (Inertia Type)

1.

Remove through-bolts and separate end cap, housing, and armature (see Figure

1).

2.

Disassemble drive assembly and drive end cap by loosening the self-locking stop nut.

3. Inspect starter for damaged or worn parts.

4. Repair or replace all damaged or worn parts, as

needed.

I -

Starter Removal

[

Accidental starting

of

the engine can result in severe personal injury

or

death. Disconnect the negative battery cable and spark plug wires while servicing engine, controls, or asso- ciated equipmenf.

Starter Assembly (Inertia Type)

1. Before reassembling the starter, wipe

off

any dirt from parts with

a

clean cloth or blow

off

with filtered, compressed air.

SEAL

I

/

STOP

NUT

PINION GEAR BRUSHES

HOUSING

BRUSH

SCREWS

'

NUT

ES-1334

FIGURE 1. STARTER MOTOR (INERTIA

TYPE)


9-1

2. Assemble brushes so that the chamfered side is away from the brush springs. Make sure brush wires do not rub against the commutator or end cap.

3. Torque brush screws to a value

of

3

to

3.5 ft-lbs (4tO

5 Nm).

4.

Torque input stud nut to a value of 4 to

5 ft-lbs (5 to

7 Nm).

5. Apply a thin film of grease to the commutator end of the armature shaft and to the portion of the shaft that contacts the bearings. Apply a generous film of silicone base grease

(GE

shaft threads.

6. Torque stop nut to a value of 20 to 25 ft-lbs (27 to

34 Nm).

7. Torque through bolts to avalueof 4.5 to 6 ft-lbs (6 to

8 Nm).

8. Apply a small amount of a silicone based grease

(GE Versilube 322-L) to armature shaft spline.

9.

Install dust cap, pinion gear, dust cover spacer, anti-drift spring, stop nut washer, and stop nut.

10.

Push dust cover on until it snaps into position.

Starter Disassembly (Solenoid

Shifl Type)

1.

Remove "M" terminal nut and wire lead from solenoid (Figure 2).

2. Remove the two solenoid mounting screws and remove solenoid.

3. Scribe a mark across frame and rear bracket to aid in assembly. Remove the two through bolts.

4.

Remove rear bracket and frame assembly.

5. Carefully remove armature and lever from front bracket. Note direction of lever and retainer.

6. Remove the two brush mounting screws, and remove the rear bracket.

7. Remove brush holder assembly from the frame by pulling the brushes out.

SCREW

FRONT

BRACKET

RETAINFR

\

LEVEF

mn

SOLENOID

\

THROUGH

BOLT

/

BUSHING

C

I

SEAL (RETAINING

RING)

\

..

\

ADJUSTMENT

OVERRUNNING

WASHERS

CLUTCH

FRAME

ASSEMBLY

BRUSH

\

. -. .. .

BRACKET

HOLDER ASSEMBLY

SCREW

ES-1665

FIGURE

2. STARTER MOTOR

(SOLENOID

SHIFT TYPE)


9-2

8.

Push stopper toward pinion and remove snap ring

(Figure 3).

9.

Remove stopper and overrunning clutch from armature shaft.

PU

OVERRUNNING CLUTCH

\

STOPPER n

U

/--

4

10.

FIGURE 3. REMOVING OVERRUNNING CLUTCH

Es-1622

Inspect starter for damaged or worn parts.

11. Repair or replace all damaged or worn parts, as needed.

Starter Assembly

(Solenoid

Shifl

Type)

1. Install seal in nose housing. Install overrunning clutch on the armature shaft.

2.

Slide stopper on the armature shaft. Position snap ring in groove in armature shaft.

3. Pull stopper all the way over snap ring (Figure 4). It may be necessary to tap snap ring into groove with a punch while maintaining tension on stopper.

SNAP RING

I

ES-1194

FIGURE 4. INSTALLING STOPPER

4. Lubrication: When starter motor is assembled apply grease to each of the following points (Recom- mended grade; Multemp PS No. 2):

0

Armature shaft spline

Both bushings (Both ends of armature)

Stopper on armature shaft

Pinion gear

0

Sliding portion of lever

5. Fit overrunning clutch into lever, and install with armature in the front bracket.

6. Install lever retainer and spacer. Position frame assembly over armature on the front bracket.

7. Install brush holder assembly. Position brushes in brush holder. Make certain positive lead wires are not grounded.

8.

Install washers, as required, on the rear end of armature shaft to obtain an armature shaft thrust gap of 0.05 to 0.5 mm (0.002 to 0.02 inch). New washers are required if rear bracket is replaced.

9-3

Solenoid

Screws

Brush Retaining Screws

Through

Bolts

6

Nm

4

Nm

5.7 Nm

(54

in.-lb.)

(33 in.-lb.)

(51 in.-lb.)

9. Install rear bracket. Secure brush holderto rear bracket with two machine screws.


10. Install and tighten the two through capscrews.

11. Install solenoid plunger in lever. Secure solenoid to front bracket with two machine screws.

12. Install wire lead to the terminal

“M”

on solenoid.

13.

After assembly, adjust pinion clearance. Pinion clearance should be 0.020 to 0.080 inch (0.5 to

2.0

mm); if not, check as follows. See Figure 5.

A. Connect starter to a battery (Figure 5). Close switch. This will shift pinion into cranking position.

B. Push pinion back by hand and measure pinion clearance. If clearance does not fall within the specified limits, adjust by adding or removing shims located between solenoid and front bracket. Adding shims decreases clearance; removing shims increases clearance. Shims are included with replacement solenoid.

/

PINION

w

FIGURE 6. TESTING ARMATURE FOR GROUNDS

ES-1001

hpecting for an Open Circuit in Armature: Using an ohmmeter, check for continuity between the commutator segments. If there

is

no continuity (high resistance), the segments are open and armature must be replaced.

Testing Armature for a Short Circuit: Use a growler for locating shorts in the armature. Place armature in growler and hold a thin steel blade(e.g. hacksaw blade) parallel to the core and just above it whileslowly rotating armature in growler. A shorted armature will cause the blade to vibrate and be attracted to the core. If armature is shorted, replace with a new one (Figure 7).

i+

PINION CLEARANCE

ES-1623

H

FIGURE 5. PINION CLEARANCE ADJUSTMENT

Inspection and Testing

Inspect the starter components for mechanical defects before testing for grounds or shorts.

Testing Armature for Grounds:Touch armature shaft or core and the end of each commutator bar with a pair of ohmmeter leads. A low ohmmeter reading indicates a grounded armature. Replace grounded armature. See

Figure

6.

.ER

9-4

ES-1002

FIGURE 7. TESTING ARMATURE

FOR

SHORT CIRCUITS


Commutator Inspection:

If commutator

is

dirty or discolored, clean with number

00 to

000 commutator

paper,

Blow grit out of armature after

cleaning.

If commutator is scored, rough, or worn, turn it down in a lathe.

Inertia type starter inspection

Housing Inspection: Permanent magnets are glued to inside of the housing. Magnets must be secure and free of cracks.

Brush Inspection:

If

brushes are worn shorter than

1 / 4

inch

(6.35

mm), replace them. Check to see that brushes move smoothly in the brush holders. See

Figure 8.

Check

for

shorts between positive side

of

brush holder and brush holder base.

If

there is continuity, replace holder assembly. Check for free movement of brushes.

All

brushes should move freely

in

the brush holders.

Overrunning Clutch: Inspect pinion and spline teeth for wear or damage.

If

pinion gear is worn or damaged, inspect flywheel ring gear also. Rotate pinion. It should turn free when turned in one direction, and lock when turned in the opposite direction. m

damage.

Do

not clean overrunning clutch in liquid cleaning solutions.

Solenoid: Push solenoid plunger in and release it. The plunger should return to its original position. While holding plunger

all

the way in, check for continuity between terminals "M" and "B'. If there is no continuity,

replace thesolenoid (Figure 10). After replacing solenoid

check pinion clearance.

f

FIGURE 8.

LIMIT

Pinion Gear: If pinion gear is badly worn, has broken teeth, or pinion splined sleeve is damaged replace pinion gear and dust cover assembly. If pinion gear is in good condition, wipe armature shaft spline and pinion clean.

Solenoid shifl type starter inspection

Field

Coil:

Use an ohmmeter to check for continuity between brushes.

If

there is no continuity, the field coil is open and must be replaced. With field coil mounted in the frame, check for continuity between the field coil and frame. Replace frame assembly if there is continuity. f3rushes:Clean around brushes and holders, wiping off all brush dust and dirt. If brushes are worn shorter than

11.5 mm

(.4528

9).

p$q-

LlMlT11*5:fi

(.4528

inch)

/

FIGURE 9.

BRUSH

WEAR LIMIT

TERMINAL'Y

TERMINAL'W'

TERMINAL

"M"

FIGURE 10. SOLENOID TERMINALS

Es-1345

Bushings: If either the front or rear bushing show signs of wear or damage, replace them. Bushing and rear bracket are replaced as an assembly. Check armature shaft thrust gap if rear bracket is replaced.

ES-1193

9-5

Remove front bushing by tapping bushing from inside with a 7/16 inch tap.

Do

not remove cap from front bracket. Thread capscrew, same size as tap, into bushing. Using a slide hammer remove bushing from front bracket. Press new bushing into front bracket.

Use

care not to distort inside diameter of bushing.


Starter Mounting

Brush Repkcement: Cut old positive brush from pigtail at the brush. Be careful not to damage field coil. Clean

/ 4

to

mm) of

brush end of pigtail

with sandpaper or emery cloth (Figure 11).

Before installing starter motor, make sure the starter mounting surface on the engine base is clean and free of oil.

PIGTAIL

STILL ATTACHED

TO FIELD COIL

4

CLEAN

(approx.

114 to 3/8 inch)

To install starter on B43G (Prior to Spec C) and B48G

(Prior to Spec E) engines use the following procedure.

On these engines starter pinion gear lash requires adjustment and must be checked when starter is installed.

SMALL CHAMFER

*ncSoLDER

BRUSH SURFACE

LARGE CHAMFER

1. Install starter

motor

and tighten mounting capscrews just enough to hold starter in place.

U

BRUSH

2. Remove spark plugs from the engine. This allows free movement of the flywheel.

FIGURE 11. BRUSH REPLACEMENT

3. Manually pull the starter pinion gear outward

on

its shaft until pinion gear teeth mesh completely with flywheel ring gear teeth. Energize solenoid on solenoid shift starter.

Push prepared end

of pigtail lead into hole in replace-

ment brush from the small chamfered side. Solder pigtail lead to replacement brush on the large chamfered side, using

50/50

240/325 Watt soldering iron. Use a file to remove any excess solder that may extend beyond brush surface.

(BCAUTIONI

Ma ferial protruding from solderedside sudace

of

brush can cause equipment damage.

Do

not use excessive solder

or

heat

and

file any excess material from brush surface.

9-6


4. Measure the amount

of

free travel (lash) between the pinion gear teeth and the ring gear teeth. See

Figure 12. If

lash is too

tight, causing binding

and

slow starter operation, or if lash is greater than

0.035 inch (0.889 mm), lash must be adjusted.

FLYWHEEL RING

GEAR

STARTER

GEAR

FREE

TRAVEL WHEN

To install starter on B43E (Beginning Spec A), B43G

(Beginning Spec

C),

and B48G (Beginning Spec

E)

engines

use

the following procedure.

On

these engines starter pinion gear lash does not require adjustment.

1.

Install starter motor and torque mounting capscrews to 24 to 26 ft-lbs (33 to 35 Nm).

2.

Install flywheel, blower housing, and cylinder air housings. For correct cylinder air housing instal- lations (required on some models), refer to Cylinder

Air Housing Clearance.

3. Connect battery cable and wires to starter. Connect battery cables to battery. Connect ground cable last.

STARTER MOTOR

PINION GEAR

-

FIGURE 12.

CHECKING

STARTER GEAR

LASH

ES-1003

5. To adjust lash on starters without slotted mounting holes, remove starter. Use a

21

164

inch (8.334 mm) drill to enlarge one mounting hole in starter mounting bracket.

6.

Install starter motor and adjust lash to 0.020 in.

3.

0.015

in. (0.51 mm

k

7. Remove flywheel and torque starter mounting capscrews to 24 to 26 ft-lbs (33 to 35 Nm). Use

Onan flangehead capscrews or SAE grade

8

capscrews with a hardened flatwasher.

Do

not use lockwashers.

-1

Failure io torque starter bolts properly can cause starter failure and ring gear

damage. -Torque starter bolts to

correct values when installing.

8.

Install flywheel spark plugs, blower housing, and cylinder air housings. For correct cylinder air housing installation (required on some models), refer to Cylinder Air Housing Clearance.

.

9. Connect battery cable and wiresto starter. Connect battery cables to battery. Connect ground cable last.


9-1


Engine

Disassembly

DISASSEMBLY/ASSEMBLY

When complete engine disassembly is necessary, first removeall complete assemblies. Individual assemblies such as fuel pump and carburetor can be disassembled and repaired at another time.

1. Use the proper bearing driverto install front main bearing after coating it with a light film of oil.

2.

Insert rear main bearing in rear bearing plate.

3. Insert crankshaft,rear bearing plate, and crankshaft gear.

4. Install piston and connecting rods.

Suggested Disassembly Order

1.

Drain crankcase.

2. Disconnect all exhaust lines and electrical lines.

3.

Remove engine from its mountings and place on a suitable bench or work stand.

4.

Remove all housings, shrouds, blower housings, etc.

5 ,

Remove flywheel, using a puller.

6.

Remove the gear cover, being careful to protect the oil seal from keyway damage.

7. Remove the crank gear, using a gear puller and ring.

8. Remove all accessories such as oil filter, starter, intake manifold, fuel lines, spark plugs, etc.

9.

Remove breaker point box.

10. Remove oil base, oil pump and cylinder heads.

11. Remove valves, springs, lifters, etc.

12.

Remove camshaft and gear assembly.

13. Remove connecting rods and pistons.

14. Remove rear bearing plate, crankshaft, and front

bearing.

5. Install camshaft and gear assembly; align crank gear mark with cam gear mark.

6. Install valve assemblies, oil pump, oil base, and cylinder heads.

7. Install breaker point box.

8.

Install all accessories such as oil filter, starter, fuel lines and spark plugs.

9.

Install gear cover with oil seal and flywheel.

10. Set breaker points to obtain proper timing.

11.

Check valve clearance.

12. Install all housings and air cleaner.

13. Fill crankcase with oil.

Operation

Start engine and check oil pressure. Run for approximately 15 minutes to bring engine to operating temperature. Check for oil leaks, fuel leaks and exhaust leaks. Adjust carburetor and governor for speed and sensitivity.

Keep all parts in their respective orders. Keep valve assemblies together. Return rod caps to their respective pistons. Analyze the reasons for parts failure.

Suggested Assembly Procedure

Testing Compression

The compression tester is used to

determine the

condition of valves, pistons, piston rings and cylinders.

To check compression:

1.

Run the engine until thoroughly warm.

2.

Stop engine and remove spark plugs.

3. Remove air cleaner and place throttle and choke in the wide open position.

4. Insert the compression gauge in one spark plug

hole.

Engine assembly is normally the reverse of the disassembly procedure, observing proper clearances and torques. Use a torque wrench to assure proper tightness. Coat the internal engine parts with oil as they are assembled. After the internal engine parts are assembled, the engine should turn over by hand freely. Use onlygenuine Onan partsand special tools when reassembling your engine.

10-1

5.

Crank the engine and note the reading.

Refer to SPEClFlCA TlONS section for compression pressures. There may

be variations due to temperature,

atmospheric conditions and altitude. These pressures are for a warm engine at cranking speed (about

300

rpm).


Tappet Adjustment

The engine is equipped with adjustable valve tappets.

The valve tappet clearance should be checked and adjusted, if necessary, at least every 200 operating hours or when poor engine performance is noticed.

Adjust the valve clearance only when engine is at ambient temperature. Proceed as follows:

1. Remove ignition key to prevent accidental starting.

2.

Remove all parts necessary to gain access to valve tappets.

3.

Remove spark plugs to ease the task of turning the engine over by hand.

4.

Place a socket wrench on the flywheel capscrew and rotate the crankshaft in a clockwise direction until the left intake valve (viewed from flywheel end) opens and closes. Continue turning the crankshaft until the TC mark on the flywheel is lined up with the TC mark on the gear cover. This should place the left piston (#1) at the top of its compression stroke. Verify that the left intake and exhaust valves are closed and there is no pressure on the valve lifters.

5.

The correct feeler gauge for the valve adjustment

(see SPEClFlCATl0NS)shouId pass freely between valve stem and tappet; a 0.002 inch thicker gauge should not (Figure 1).

(0.05

mm)

6.

To correct the valve clearance, use a 7/16-inch open end wrench to turn the adjusting screw to obtain the correct clearance. The screw is self- locking and will stay where it is set. A 9/16-inch

(14 mm) open end wrench is required to hold the tappet while turning the adjusting screw.

7.

To

adjust valves on the right hand cylinder, turn engine one complete revolution and again line up mark on the flywheel and the TC mark on the gear cover. Then follow adjustment procedure given for left hand cylinder.

8.

Replace all parts removed in Step 2. Tighten all screws securely. Torque manifold bolts to specified torque.

VALVE SYSTEM

A

properly functioning valve system isessential for good engine performance.

All engines utilize an L-head type

valve design as shown in Figure 1. Access

to the valve system can be obtained by removing the cylinder heads and thevalve coverson top of the engine. Avalvespring compressor must be used to remove valves from the cy1 i nder block.

A valve stem seal is used on the intake valve guides of

some engines. This seal must be replaced each time the valve is removed.

Place valves, springs, retainers, and tappets in a rack as they are removed from cylinder block so they can be identified and reinstalled in their original locations.

Discard old valvestem seals and replace with new ones during assembly.

Use the following procedures to inspect and service the valve system.

Inspection

Clean carbon from the valves, valve seats, valve guides, and cylinder block.

Valves: Check the valve face for evidence of burning, warpage, out-of-round, and carbon deposits.

Burning and pitting are caused by the valve failing to seat tightly. This condition is often caused by hard carbon particles on the seat. It may also be due to weak valve springs, insufficient tappet clearance, warpage, and misalignment.

t

NOTE: USEA STANDARD AUTOMOTIV

'ETYPE

,

J

CTT

VALVE

pj

VALVE CLEARANCE

E

VALVE RETAINER

VALVESPRING,

VALVE A D J U n l N G

SCREW

I

' '

I

ONLY) SEAL

FIGURE

1.

VALVE ASSEMBLY

10-2

ALVE ROTATOR

VT-1005


I

I

+

Warpage occurs chiefly in the upper stem due to its exposure to intense heat. Out-of-round wear follows

when

the

seat

is

pounded by a valve

whose head is not

in

line with the stem and guide.

If a

valve face

is

burned or warped, or if the stem is worn, install a new valve.

Too much clearance in the intake guide admits air and

oil

into the combustion chamber, upsetting carburetion, increasing oil consumption, and making heavy carbon deposits. Carbon reduces heat dissipation. Clean metal is a good heat conductor but carbon insulates and retains heat. This increases combustion chamber temperatures which causes warping and burning.

-1

Driving out old valve guides can cause guide and tappet bore damage. Do not strike guide or tappet bores wiih driver during removal.

Valve Guide Installation: Run a small polishing rod covered with crocus cloth through valve guide holes to clean out carbon and other foreign materials. Place a new gasket on the intake valve guide, and coat the outer edgeof each new guide with

oil.

Placeguide, notch-up, in cylinder block and press in until guide stops or protrudes

11

132

inch

(8.7 mm) from rocker box side of block. A suggested method of installation is shown in

Figure 3.

Unburned carbon residue gums valve stems and causes them to stick in the guide. Deposits of hard carbon with sharp points projecting become white hot and cause pre-ignition and pinging.

Refinish valves that areslightly pitted or burned on an accurate valve grinder. If valves are badly pitted or have a thin margin when refacing, replace them.

ROD

4

5/16-18 HEX, NUT

(2

\

VT-1020

FIGURE 2. VALVE STEM AND VALVE GUIDE INSPECTION

Stems And Guides: Always check valve stems and

guidesfor wear as shown in Figure 2. Use a hole gauge

to measure the valve guide. When clearance with stem exceeds original clearance by that specified in

DIM-

ENSlONS AND CLEARANCES

replace either valve or guide or both, as may be necessary. Always regrind seat to make concentric with the newly installed guide.

VT-1023

Worn valve stem guides can be replaced from inside the valve chamber (a seal is provided behind the intake valve guides only). The smaller diameter of the tapered valve guides must face toward the valve head.

Tappets are also replaceable from the valve chamber after first removing the valve assemblies.

FIGURE 3. VALVE GUIDE INSTALLATION

Valve Stem Seals: Do not reuse valve stem seals. Each time the valves are removed from cylinder block, a new seal must be used when valve is reinstalled. Valve Guide Remova1:Before removing valve guides, use an electric drill with a wire brush to remove carbon and other foreign material from top surface of guides. Failure to perform this operation may result in damage to the guide bores. Drive the guides out with a hammer and valve guide driver.

10-3

[BCAUTIONI

Removing a valve after installing valve stem sealcan cause sealdamage. Do not allow valve stem groove to come in contact with valve sfem seal after installation.


Value Spring: Check valve springs for cracks, worn ends, distortion, and tension. If spring endsare worn, check valve spring retainer for wear. Check for spring distortion by placing spring on aflat surface next to a square. Measure height of spring and rotate it against square edge to measure distortion. If distortion exceeds 0.06 inch (1.5 mrn) replace spring. Check spring tension at the installed height for both the valve open and closed position using an accurate valve spring tester. Replace any valve spring that is weak, cracked, worn, or distorted.

Valve Rotators: Positive type valve rotators prolong valve life and decrease valve repairs. When functioning properly, the valve is rotated a fraction of a turn each time it opens. While at open position, the valve must rotate freely. There is no easy way to determine if a valve rotator is good or bad. Onan recommends that valve rotators be replaced at each major overhaul or i f a build-up of carbon is noted on valve face and valve seat.

Walve Seats: Inspect valve seat inserts. If seats are loose, cracked or severely pitted, new ones must be installed. Remove valve seat inserts using a valve seat removal tool. If valve seat insert bores in cylinder block are damaged or worn so that a press fit cannot be obtained when installing new standard size valve seat inserts, the bores must be machined for an oversize seat.

USE

NEW VALVE SEAT TO

ADJUST PULLER DEPTH

Valve Seat Removal: Remove carbon and combustion deposits from valve seat. Select proper puller size determined by inside diameter of valve seat. On some pullers use a new seat as a guide to adjust puller depth

(Figure 4). Puller jaws must expand into cylinder block at the point where bottom of valve seat insert rests on cylinder block (Figure 4). Position puller on valve seat and tighten hex nut. Clamp cylinder block to a solid bench. Attach slide hammer to puller. Tighten hex nut between each blow with the slide hammer.

VAL

L

CHECK THIS SURFACE

FOR

BURRS BEFORE

INSERTING SEAT

*

VT-1

ow

FIGURE 5. INSERTING NEW VALVE SEAT

PULLER JAWS

FIGURE 4. VALVE

SEAT

REMOVAL

Valve Seat Installation: After the old seat has been removed, clean out any carbon or metal burrs from the seat insert recess. Use a valve seat insert driver and hammer to install the insert (Figure 5). Drive the valve seat insert in so that the insert enters the recess evenly.

Make certain that the valve seat insert rests solidly on the bottom of the recess all the way around its circumference.

C-1104

10-4

Insert valve seat staker into valve seat or guide in cylinder block. Using a lead hammer, strike the staking tool asharp blow

to

wedge new valvesecurely in place.

It will

be

necessary to refinish valve seat inserts before installing valves.

To assure a tight valve seat fit and eliminate the danger

of

seat loosening in the bore, valve seat must be staked.


*

b

*

,

TAPPETS

Very little wear takes place on tappet diameters or in tappet bores.

If the clearance

between tappet

and

bore in cylinder block exceeds specifications, replace the tappet.

Inspect the tappet faces which contact camshaft lobes for roughness, scuffing, or concave wear.

Replace any worn tappets. If tappets are worn, inspect camshaft for wear.

VALVE FACE AND SEAT GRINDING

Some engines are equipped with a premium valve package (aluminized intakevalves). If the aluminized valve face does not clean-up using a wire brush, the valve face may be refinished. This removes the aluminized coating from thevalveface. An aluminized valve that has been refinished will normally have a life expectancy equal to a standard valve. If longer valve life is required, worn or damaged valves should be replaced with new premium valves.

Before installing new valves or previously used valves, inspect valve seats for proper valve seating.. If used valves are reinstalled, the valve stems should be cleaned and valve faces ground to their specified angles of 44". Refinish valve seats to a 45" angle.

When refacing valves and seats, remove all evidence of pitting and grooving. If end of valve stem is pitted or worn, true it and clean it up on the refacer wheel. A very light grind is usually enough to square stem and remove any pits or burrs. The valve guide should be thoroughly cleaned. If valve guide is worn, or valve is warped, the necessary parts must be replaced.

By grinding the valve face and seat at slightly different angles, a fine line of contact on face and seat is obtained, eliminating the need to lap the seating surfaces. The one degree difference in angles is defined as the interference angle (Figure 6). The seat angle is greater than that of the valve face. This assures contact at the maximum diameter on valve seat seating surface.

Refinish valve faces to a 44" angle on a valve refacing machine. The first cut from valve face

must

be a light grinding. Check if there is an unevenness of metal being

removed. If only part of valve's face has been

touched, check to see if valve is properly seated in machine or

if

valve is warped, worn,

or

distorted. When cut is even around the whole valve face, keep grinding until complete face is ground clean. Be sure the correct valve face angle is maintained. When valve head

is

warped, a knife edge will be ground (Figure 7) on part or all of the head due to the large amount of metal that must be removed to completely reface valve. Heavy valve heads are required for strength and good heat dissipation.

Knife edges lead to breakage, burning, and pre-ignition due to heat localizing on the edge.

Replace any valve that cannot be entirely refaced while keeping a good valve margin (Figure 7) or is warped, worn, or damaged in any way. The amount of grinding necessary to true a valve indicates whether valve head is worn or warped.

WARPED

VALVE

WITH

KNIFE EDGE KNIFE EDGE

GOOD MARGIN

74

1 I

1/16 INCH

(1.6mm)MlNlMUM

FIGURE 7. VALVE HEAD MARGIN

M-1114

When new valve seats are installed, or previously used seats reground, refinishing must be done with a valve seat grinder used according to the manufacturer's directions.

FIGURE 6. VALVE INTERFERENCE ANGLE

Valve seats should be ground with a 45 degree stone and the width of theseat band should be 1/32 inch to

3/64 inch (0.79 to 1.2 mm) wide. Grind only enough to assure proper seating.

VT-1021

10-5

Place each valve in its proper location. Check each valve for a tight seat. Make several marks at regular intervals across the valve face using machinist's bluing. Observe if the marks rub off uniformly when the valve is rotated part of a turn against the seat. The valve seat should contact the valve face evenly at all points. The line of contact should be at the center of the valve face.


FLYWHEEL

Removing the flywheel isa relatively simple process, but the following procedure must be followed to avoid damage to the gear case and possible injury to the operator.

1.

Turn the flywheel mounting screw outward about two turns.

pAEI

result in severe personal injury.

Do not remove flywheel screw completely when using flywheel puller.

2.

Install a puller bar on the flywheel as shown in

Figure 8.

GEAR COVER

After removing the mounting screws, tap the gear cover gently with a

soft

faced hammer to loosen it (Figure 9).

When installing the gear cover, make sure that the pin in the gear cover engages the nylon lined (smooth) hole in the governor cup. Turn the governor cup

so

that the nylon lined hole is at the three o’clock position. Use a small amount of grease to assist in holding governor cup in position. The smooth side of the governor yoke must ride against the governor cup. Turn the governor arm and shaft clockwise as far as possible-and hold in this position until the gear cover is installed flush against the crankcase. Be careful not to damage the gear cover oil seal.

c

FLYWHEEL

MOUNTING SCREW

U

cs-lo00

FIGURE

8. BLOWER WHEEL PULLEY

R O L L P I N

\+GOVERNOR

ROTATE

GOVERNOR CUP

SO

T H A T R O L L PIN’

FITS INTO T H E

METAL LINED

HOLE OR PLASTIC

E U S H ~ G THE CUP

I

/,I

I

ARM

GOVERNOR

SHAFT YOKE

(Smooth

Side

Toward Cup)

UI

L

aEAL

3. Turn the puller bar bolts in, alternately, until the wheel snaps loose on the shaft.

1 -

use any

tools

Improper flywheel removal can cause gear case damage.

Do

not to pry against gear cover when removing iiywheel.

4.

Unscrew the puller from the flywheel, remove the flywheel mounting screw and washer and pull the flywheel

off

the

shaft.

Take care not to drop the wheel.

A

bent

or

broken fin will destroy the balance.

Always use a steel key for mounting the flywheel.

10-6

IF FEELER WILL

ENTER HOLE

112”

BALL HAS

FALLEN OUT

FIGURE 9. GEAR COVER ASSEMBLY

by any means, is strictly prohibited.

1

WHEN GOVERNOR

IS

PROPERLY

ON

ORAWING WILL

RIGHT

INSTALLATION OF BALLSPACER

v

WRONG

C-1107

4

4

5

BALL GOVERNOR 6 BALL GOVERNOR 8 BALL GOVERNOR

FLYBALL LOCATIONS

CS-1238

FIGURE

10. GOVERNOR

CUP

DETAILS

GOVERNOR CUP

With the gear cover removed, the governor cup can be taken off after removing the snap ring from the camshaft center pin. Catch the flyballs while sliding the cup off

(Figure

10).

cannot be pulled outward or removed without damage.

If the center pin extends out too far, the cup will not hold the flyballs properly. If the distance is less than

7/32”

remove the center pin and press in a new pin.

Replace with a new part any flyball which is grooved or has a flat spot; the ball spacer if its arms are worn or otherwise damaged; the gear/spacer assembly if loose on gear hub, and the governor cup if the race surface is grooved or rough. The governor cup must be a free- spinning fit on the camshaft center pin, but without any excessive play.

TIMING GEARS

If replacement of either the crankshaft gear or the camshaft gear becomes necessary, always install both gears new.

If

replacing the ball spacer, be sure to position it

so an

arm is lined up with the space on the camshaft gear (if your camshaft gear does not have a space in it, disregard this paragraph). If the ball spacer arm is not lined up with the space in the camshaft gear, a flyball can slip into the space and cause engine racing and

governing problems (Figure 10).

The camshaft and gear must be replaced as an assembly.

Before removing the camshaft and gear assembly, remove the cylinder head and valve assemblies. Then remove the operating plunger for the breaker points and tappets.

To remove the crankshaft gear, first remove the snap ring and retainer washer, then attach the gear pulling ring using two No.

screws (Figure

11).

Tighten the screws alternately until both are tight. Attach a gear puller to the puller ring and proceed to remove the gear. When installing the governor cup, tilt the engine so the gear is up, put the flyballs in place (Figure

lo),

and install the cup and snap ring on the center pin.

The camshaft center pin extends out

314

inch

(19

mm) from the end of the camshaft. This distance provides an in-and-out travel distance of

7/32

(5.6

governor cup, as illustrated. Hold the cup against the flyballs when measuring. The camshaft center pin

10-7

Each timing gear is stamped with “0” near the edge. The gear teeth must mesh

so that these marks exactly

coincide when the gears are installed in the engine.

When instalfing the camshaft gear and shaft assembly, be sure that the thrust washer is properly in place behind the camshaft gear. Then install the crankshaft retaining washer and lock ring.


CRANKSHAFT

GEAR PULLER

E MARKS

LIGN WHEN

ING TIMING

EARS

VT-1029

FIGURE

11.

TIMING GEAR REMOVAL AND INSTALLATION

PISTONS AND CONNECTING RODS

Observe the following procedure when removing pistons and connecting rods from the engine.

1.

Drain Oil.

2. Remove the cylinder head and oil base pan from the engine.

3. Remove the ridge from the top of each cylinder with a ridge reamer before attempting piston removal

(Figure 12).

1

Improper piston removal can cause piston damage. Use ridge reamer to remove cylinder ridge before removing piston.

4. Turn the crankshaft until the piston is at the bottom of its stroke and remove the connecting rod nuts. Lift the rod bearing cap from the rod and push the rod and piston assembly out through the top of the cylinder using a hammer handle. Avoid scratching the crankpin and cylinder wall when removing the piston and rod.

Mark each piston and rod assembly

so

they can be returned to their respectivecylinders after overhaul.

Keep connecting rod bearing caps with their respective rods.

5. Remove the piston rings from the piston with a

piston ring spreader asshown in Figure 13. Remove

the piston pin retainer and push the piston pin out.

L

L

FIGURE

13.

REMOVING PISTON RINGS

FIGURE 12. REMOVING RIDGE

FROM CYLINDER

Remove dirt and deposits from the piston surfaces with an approved cleaning solvent. Clean the piston ring grooves with agroove cleaner or the end

of

a piston ring

filed to a sharp point (Figure 14). Care must be taken not

to remove metal from the groove sides. m

cleaning solvent

Do nof use a caustic

or

wire

brush

for cleaning pistons.

104

When cleaning the connecting rods in solvent, be sure to include the rod bore.

Blow out all passages with compressed air.


82

1

FIGURE 14. PISTON GROOVE CLEANING

Inspection

Follow the procedures given below when inspecting pistons and connecting rods.

Piston Inspection:

1. Inspect the pistons for fractures at the ring lands, skirts and pin bosses. Check for wear at the ring lands using a new ring and feeler gauge

as shown in Figure 15. Replace the piston when

the side clearance of the top compression ring exceeds that specified in

DIMENSIONS AND

CLEARANCES.

2.

Replace pistons showing signs of scuffing, scoring, worn ring lands, fractures or damage from preignition. Excessive piston wear near the edge

of the top ring land indicates preignition.

Connecthg Rod Inspection:

1. Replace connecting rod bolts and nuts with damaged threads. Replace connecting rods

10.9

FIGURE 15. CHECKING RING

SIDE

CLEARANCE

with deep nicks, signs of fractures, scored bores or bores out of round more than 0.002 inch.

2.

Use a new piston pin to check connecting rod for wear.

A

push fit clearance is required and varies from engine to engine. If a new piston pin falls through a dry rod pin bore as a result of its own weight, replace the rod.

Fitting Pistons:

1.

Proper piston tolerances must be maintained for satisfactory operation.

.

2. Refer to DIMENSIONS AND CLEARANCES to determine where to measure piston to be sure the total clearance follows specifications.

1

I

I

I

I o

0

0

0

0 1

c

MEASURECLEARANCEHERE

FIGURE 16. MEASURING

PISTON

CLEARANCE


fitting Piston Rings:

1. Install the piston ring in the cylinder bore. Invert the piston and push the ring to the end of ring travel, about halfway into the bore, which trues the ring end gap. Check the gap with a feeler

gauge (Figure 17).

2. The practice of filing ring ends to increase the end gap is not recommended. If the ring end gap does not meet specifications, check for the correct set of rings and the correct bore size A cylinder bore that is 0.001 inch

(0.03 mm) under size will reduce the end gap

0.003 inch (0.08 mm).

Cleaning

After removing pistons, crankshaft, cylinder heads, etc., inspect block for cracks and extreme wear. If block is still serviceable, prepare it for cleaning as follows:

1. Scrape all old gasket material from block. Remove oil by-pass to allow cleaning solution to contact inside of oil passages.

2. Remove grease and scale from cylinder block by agitating in .a bath of commercial cleaning solution

or

hot soapy washing solution.

3. Rinse block in clean hot water to remove cleaning solution.

Inspection

When rebuilding theengine, thoroughly inspect block for any condition that would make it unfit for further use. This inspection must be made after all parts have been removed and block has been thoroughly cleaned and dried.

1.

Makeathorough check forcracks. Minutecracks may be detected by coating the suspected area with a mixture of 25 percent kerosene and 75 percent light motor oil. Wipe the part dry and immediately apply a coating of zinc oxide (white lead) dissolved in wood alcohol. If cracks are present, the white coating will become discolored at the defective area. Always replace a cracked cylinder block.

2. Inspect all machined surfaces and threaded holes.

Carefully remove any nicks

or

burrs from machined surfaces. Clean out tapped holes and clean up any damaged threads.

3. Check top of block for flatness with a straight edge and a feeler gauge.

CyMnder Bore Inspection: Inspect cylinder bores for scuffing, scratches, wear, and scoring. If cylinder bores are scuffed, scratched, scored, or worn, they must be rebored and honed for the next oversize piston.

When the appearance of cylinder bores is good and thereare noscuff marks, check cylinder bore forwear or out of roundness as follows:

FIGURE 17. POSITIONING OF PISTON RING

AND MEASURING OF END GAP

CYLINDER BLOCK

1. Check cylinder bore for taper, out of round, and wear with a cylinder bore gauge, telescope gauge or inside micrometer. These measurements should be taken at four places, top and bottom of piston ring travel, parallel and perpendicular to axis

of

crankshaft.

The cylinder block is the main support for all other basic engine parts. Crankshaft and camshaft are supported by the block, assuring alignment of the crankshaft and cylinder bores.

10-10

2.

Record measurements taken at top and bottom of piston travel as follows (Figure 18):


L

,

A.

Measure and record as

“A” the cylinder bore diameter (parallel to crankshaft) near the top

of

cylinder bore where greatest amount

of

wear occurs.

B.

Also

measure and record as “B”cy1inder bore diameter (parallel to crankshaft) at the bottom

of

piston travel.

C. Measure and record as

“C” cylinder bore diameter (perpendicular to crankshaft) near the top

of

cylinder bore where greatest amount of wear occurs.

D. Also measure and record as “D” cylinder bore diameter (perpendicular to crankshaft) at the bottom of piston travel.

TOP

END OF CY LlNDER

e418

BOTTOM OF

RING TRAVEL

RING

,WEAR

AREA

b

4

E. Reading ”A’subtracted from reading “B” and reading

“C”

subtracted from reading “D” indicates cylinder taper.

If cylinder taper exceeds that specified in

DIM-

ENSlONSAND CLEARANCES rebore and hone cylinder to the next oversize

F. Reading reading “B’ compared to reading “D” indicate whether

or

not cylinder is out of round. If out of round exceeds that specified in

DlMfNSlONS

AND CLEARANCES, the cylinders must be rebored and honed to the next oversize. A reboring machine is used when going to oversize pistons.

FIGURE 18. METHODS OF MEASURING THE DIAMETER

OF A CYLINDER BORE

Reboring the

Cylinder

Rebore and hone engine whenever cylinder bore is worn, damaged, out

of

round,

or

if cylinder taper exceeds specifications. A worn cylinder bore should be resized to the smallest standard oversize diameter at which it will clean up.Thefinalfinishand borediameters should then be obtained by honing. Final bore diameter should equal the standard diameter added to the oversize.

After boring to the correct oversize cylinder bore dimension piston and ring clearance should be appropriate. There is no need to adjust or“fit” pistons and rings.

When reboring cylinders, take the following precautions:

1. Make sure cutting tool

is

properly ground before using

it.

Improper boring

wi//

resulf in engine

k@%!@!l

damage. Boring

musf

be done by qualified mechanics.

10.1 1

2. Be sure top of engine block is smooth and deposit free.


3.

Clean base of boring bar before bar is set up.

Deposits under boring bar will cause it to tilt and the cylinder will be distorted after boring.

4. Makean initial roughcut,followed byafinishcut.

Then hone cylinder bore to the specified oversize.

Deglazing Cylinder Bores

Deglaze the cylinder bores if there are no scuff marks and no wear or out of round beyond specifications before installing new rings. Deglazing gives a fine finish, but does not enlarge cylinder diameter, so the original pistons with new rings may still be used.

The reason for deglazing a cylinder is to provide cavities to hold oil during piston ring break-in.

1.

Wipe cylinder bores with a clean cloth which has been dipped in clean, light engine oil.

2. Use a brush type deglazing tool with coated bristle tips to produce a crosshatch pattern in the cylinder bore.

Honing Cylinders (Using Precision Hones)

Refer to hone manufacturer’s recommended grit size to produce specified surface finish of 20 to 40 RMS. Too rough of a finish will wear out the rings and cause excessive oil consumption and too smooth of afinish can retard piston ring seating.

1. Position block solidly for either vertical or hori- zontal honing. Use either a drill press or heavy- duty drill which operates at approximately 250 to

450 rpm.

2. Follow hone manufacturer’s instructions for the use of oil or lubricant on stones. lubricants with a dry hone.

Do

not use

3. Insert hone in bore and adjust stonestofit snugly to the narrowest section. When adjusted cor- rectly, the hone should not shake

or

chatter in cylinder bore, but will drag freely up and dowg when hone is not running.

3. Use a slow speed drill to drive the deglazing tool.

Move deglazing tool up and down in cylinder (10 to

12 complete strokes) rapidly enough to obtain a crosshatch pattern (Figure 19).

4.

Connect drill to honeand start drill. Feel out bore for high spots, which cause an increased drag on stones. Move hone up and down in bore with short overlapping strokes about

40 times per minute. Usually bottom of cylinder must be worked out first because it is smaller. As cylinder takes a uniform diameter, move hone up and down all the way through cylinder bore.

PRODUCE CROSS HATCH SCRATCHES

FOR FAST RING SEATING

AVOID THIS FINISH

5. Check diameter of the cylinder regularly during honing.

A

dial bore gauge

is

the easiest method but a telescoping gauge can be used. Check size at six places in bore; measure twice at top, middle and bottom at 90-degree angles.

6.

Crosshatch formed by the stones should form an included angle of 23 degrees. This can be achieved by moving the rotating hone (250 to450 rpm) up and down in cylinder bore about

40 times per minute.

7.

Clean cylinder bores thoroughly with soap, water and clean rags. A clean white rag should not become soiled on wall after cleaning is complete.

Do not use a solvent or gasoline since they wash oil from the walls but leave the metal particles.

8.

Dry crankcase and coat it with oil.

I

FIGURE 19.

CROSS

HATCHING

ACAUTION

Improper cylinder cleaning will result in engine damage. Do

not

use gasoline, solvents, or commercial cleaners to clean cylinder bores.

4.

Clean cylinder bore thoroughly with soap, water and clean rags. Continue cleaning until a clean white rag shows

no

discoloring when wiped through cylinder bore.


10-12

L

1

L

I

C

CRANKSHAFT

Clean

crankshaft thoroughly

and

inspect journals

for

scoring, chipping, cracking, or signs

of

overheating.

If

crankshaft has overheated, is scored, or excessively worn, reconditioning

or

replacement will be required.

Examine bearing journals for cracks if overheating has occurred.

Measure crankshaft main bearing and connecting rod journals at several places on their diameter to check for roundness and taper.

The only recommended method of reconditioning the crankshaft

is

regrinding, as required to accommodate undersize bearings. Metallizing

of

bearing journals is not recommended.

If regrinding of crankshaft journals is necessary, the work should be done by a reputable machine shop that has suitable equipment to handle precision work of this type. Undersize main bearings are available in sizes of

0.01 0, 0.020, and 0.030 inch. Undersize connecting rods are available in sizes of 0.010, 0.020, 0.030 and

0.040 inch.

Whenever making major repairs on the engine, always inspect the drilled passages

of

the crankshaft. Clean them to remove any foreign material and to assure proper lubrication

of

the connecting rods.

BEARINGS

With camshaft and crankshaft removed, use a micrometer to measure diameter of bearing journals. Use a dial bore gauge

or

a telescopic gauge and micrometer to measure inside diameter of bearings. Refer to

DIMENSIONS AND CLEARANCES to determine if clearances are within specifications.

Any bearing that is scored, chipped, pitted or worn beyond the specified limits must be replaced.

Removal

of

the camshaft bearings requires complete disassembly of the engine. Use a press or a suitable driver to remove bearings. Support casting to avoid distortion and to avoid damaging the bearing bore during removal and installation.

HOLE IN

BEARING

IN

BEARING BORE

CAWSHAFT BEARING

7/32' (5.6 m m )

FROM

OUTSIDE

FIGURE 20. FRONT

CAMSHAFT

BEARING

Replacement camshaft bearings are precision type which do not require line reaming or line boring after installation. Clean outside of the bearing and bearing bore in the block. Before installing cam bearings use

Locktite Bearing Mount on outside diameter of bearing.

Use a combination bearing driver to install bearings.

Place the bearing on the crankcase over the bearing bore with the lubricating hole (front only) in the proper position. Be sure to start the bearing straight. Press in the front bearing flush with the outside end of the bearing bore. Front cam bearing oil hole must line up

with oiling hole in cylinder block (Figure 20). Press in

the rear camshaft bearing until past the ignition plunger hole. Lubricate bearing surfaces with oil after installing.

New crankshaft main bearings are precision type which

do

not

require line reaming or line boring after installation. Usea press ora suitable driverto remove bearings.

Support casting to avoid distortion and to avoid damaging the bearing bore during removal and installation.

Before installing main bearings, expand bearing bore by placing the casting in an oven heated to 200°F (94OC). If practical, cool the precision bearing to shrink it.

Before installing the front main bearing, usethe towelette included with the bearing kit to clean the outside of the bearing and bearing bore in the block.

Breathing

vapor from fowelefte

prolonged confacf with

and skin

can be harmful. Use only in well ventilated area and avoid prolonged contact

with

skin.


10-13

After allowing three to four minutes for drying, apply the

Locktitefrom the small tube to the mating surfaces of the bearing and the bearing bore. Align the oil holes in the bearing with the oil holes in the bearing bore (Fig-

ure 22). The oil passage should be at least half open.

Install the bearing flush with the block, using the combination driver. Wipe

off

any exesss Locktite around the bearing. Allow at least one hour for hardening at room temperatu re.

REAR BEARING END P L A T E

ALIGN BEARING

OIL

HOLES

WITH O I L HOLES IN

BEARING BORE

THRUST

WASHER

In the rear bearing plate, install the bearing flush to

1 /64 inch

(0.40

to align the oil holes in the bearing with the oil holes in the bearing bore(Figure 21). The oil passage must be at least half open. Lubricate bearing after installation.

If head of lock pin is damaged, use side cutters or Easy

Out tool to remove and install new pin. Oil grooves in thrust washers must face the cranksahft, and washers must be flat (not bent). The two notches on each washer must fit over the two lock pins to prevent riding on the

crankshaft (Figure 21).

Lubricate the front main bearing lightly with oil and insert the crankshaft. With the rear bearing plate gasket in place and the rear plate bearing lubricated, slide the thrust washer (grooves toward crankshaft) and plate overtheendofthecrankshaft. Line up notches ofthrust washer with lock pins before tightening end plate or lock pins will be damaged.

FIGURE 21. BEARINGS

FOR

REAR BEARING PLATE

Engines shipped from the factory have separate thrust washers and main bearings for both front and rear of engine. Front bearing replacement part is a one piece bearing (with attached thrust washer) as shown in

Figure 22.

Do

not add an additional thrust washer to this front bearing.

FRONT MAIN

BEARING BORE

1

CRANKSHAFT ENDPLAY

After the rear bearing end plate has been tightened, using the torque recommended in

ASSEMBLY TORQUES

AND SPECIAL TOOLS, check the crankshaft endplayas

shown in Figure 23. If there is

too much endplay (see

DlMENSlONS AND CLEARANCES for minimum and maximum endplay), remove the rear bearing end plate

and add a shim (Figure 21) between the thrust washer

and plate. Reinstall the end plate, making sure the thrust washer and shim notches line up with the lock pins.

Torque and recheck endplay

of

the crankshaft.

I E N T

FRONT MAIN

BEARING

MEASURE ENDPLAY HERE

(REFER TO DIMENSIONS

AND CLEARANCES)

1

FIGURE

23.

CRANKSHAFT ENDPLAY


FIGURE 22. FRONT BEARING INSTALLATION

10-14

Checking Bearing Clearance With Plastigauge

The most

accurate

means of

determining

bearing

clearance is

by

using micrometers. However,

if

crankshaft is installed in engine, bearing clearance may be measured by using a plastic strip (Plastigauge) manu- factured for this purpose.

1, Make certain that all parts are marked or identified so that they are reinstalled in their original positions. using aclean dry cloth, thoroughly clean all oil from crankshaft journal and connecting rod.

2. Place a piece

of

correct size Plastigauge in the bearing cap the full width of the journal surfaceand about

1

/4 inch

rnrn) off

center (Figure 24).

3. Rotatethe crankshaft about30 degreesfrom bottom dead center and reinstall the bearing cap; tighten rod bolts to the torque specified in

ASSEMBLY

TORQUES

AND SPEClAL

TOOLS.

Do

not turn the crankshaft.

FIGURE 24. MEASURING BEARING CLEARANCE

4. Remove bearing cap.Theflauened Plastigaugewill be found adhering to either the bearing cap or crankshaft.

5-

Plastigaugewiththegraduations on Plastigauge envelope to determine clearance.

The number within the matching graduation on the envelope indicates total clearance in millirnetres or thousandths of an inch.

OIL SEALS

The bearing plate must be removed to replace the oil

seal (Figure 25). Drive the oil seal out from the inside.

Before installing seals, fill thespace between lips with a multi-purpose grease. This will impiove sealing.

When installing the gear cover oil seal, tap the seal inward until it is .645 inch

(1 gear cover.

When installing the bearing plate oil seal, tap the seal into the bearing plate bore to bottom against the shoulder in the

plate

bore. Use a seal expander or place a piece of heavy paperaround theend of thecrankshaft, when replacing the bearing plate to avoid damaging the seal. Remove the paper as soon as the plate is in place.

FRONT

MOUNTING FACE

OF

GEAR COVER

REAR BEARING PLATE

THIS SURFACE SHOULD BE

CLEANED OF ALL

OLD

SEALING COMPOUND

BEFORE INSTALLING SEAL

,645

INCH

u

SEAL TO SHOULDER

OF THE PLATE BORE

THIS GEAR COVER SURFACL

SHOULD BE CLEANED OF ALL

OLD SEALING COMPOUND

BEFORE INSTALLING SEAL.

GEAR COVER OIL SEAL REAR

REARING

PLATE

OIL SEAL

LS-1163

FIGURE 25. GEAR COVER AND REAR BEARING PLATE

OIL

SEALS


10-15

PISTON

ASSEMBLY

Lubricate all parts with engine oil.

Position piston on its respective rod and install the pin.

Install the rings on the pistons starting with the oil

control ring (Figure 26).

Use

a piston ring spreader to prevent twisting or excessive expansion of the ring. Compression rings have a dot or the word

“top” on one side of the ring to indicate which side faces the top

of

the piston. Unmarked piston rings can be installed either way. The oil control ring has an expander; install the expander first and then close until the expander ends butt. The joint should be 180 degrees from the gap

of

that ring.

CT-1047

FIGURE 26. PISTON RINGS

INSTALLATION OF PISTON IN CYLINDER

1.

Turn the crankshaft to position the number one rod bearing journal at the bottom

of

its stroke.

2.

Lubricate the number one piston assembly and inside

of

the cylinder. Compress the rings with a ring

compressor (Figure 27).

FIGURE

27. INSTALLING PISTON

AND

CONNECTING

ROD

3.

Position the piston and rod assembly in the cylinder block. Notched side

of

connecting rod must face camshaft. Rod bolts must be off-set toward outside

of

block.

4.

Tap the piston down into the bore with the handle end of a hammer until the connecting rod is seated

on the journal (Figure 27). Install the bearing cap on

the rod. Install one fastener and tighten to 5 ft-lbs

(7 Nm).

Repeat this for the other fastener. Tighten

10-1

6

Install the remaining piston and rod in the same manner. Crank the engine over by hand to see that all bearings are free.

5.

Install the oil base with a new gasket.

6.

Install the cylinder heads. See Cylinder Headsection for torques and torquing procedure.

7.

Replace

oil

Redistribution or publication of this document, and break in engine.

t

P

6

4

CYLINDER

HEADS

Remove

the cylinder heads for lead cleaning and gasket change at least

every 200 hours, or when

poor engine performance is noticed. For engines running on un- leaded fuel this interval may be extended to

400

hours.

5.

Follow the head torque sequence shown

in

Figure 28.

A.

Graphoil head gasket torque procedure:

1. Use a 112 inch (13 mm) socket wrench to remove cylinder head

bolts. Lift

heads

off.

Tightenall boltsto5 ft-lbs(7 Nm),then

10

ft-lbs

(1

4

Nm), then to the torque specified in ASSEM-

BLY TORQUES. Recheck all head bolts for correct torque. j

ACAUT'oN

heads when hot (above

700°F

B.

137"

C]) will result in head damage. Allow heads to

cool to below 100°F (37°C)

before torquing or removing.

Asbestos head gasket torque procedure:

Tighten all boltsto 5 ft-lbs

(7 Nm), then 10 ft-lbs

(1 4 Nm), then to the torque specified in

ASSEM-

BLY TORQUES. Recheck all head correct torque.

bolts

for

2.

After removing heads, clean out all carbon deposits.

Be careful not to damage the outer sealing edges where gasketsfit.The headsare made ofaluminum and can be damaged by careless handling.

ALIGNING BLOWER WHEEL,

VENTURI

AND CHAFF SCREEN

3.

Use new head gaskets and clean both the heads and the cylinder block thoroughly where the head gaskets rest.

It may be difficult to line up the screw holes in the blower housing chaff screen with those in theventuri and those in the blower wheel if these parts are separated without noting their relative positions. The holes will match

up

if the parts are aligned as shown in Figure 29.

4.

Place a head gasket on the cylinder blockand align the holes in the gasket with the holes in thecylinder block. While holding the gasket against the cylinder head, carefully install the cylinder head on the engine. Do not attempt to slide the head bolts through thegasket without thecylinder block behind it or the gasket may tear.

NO. 1 CYLINDER

NO. 2 CYLINDER

FIGURE

28. CYLINDER HEAD TORQUE SEQUENCE c-1002

10-1 7

cs-1WI

FIGURE

29. BLOWER WHEEL, VENTURI AND

CHAFF SCREEN ALIGNMENT


CYLINDER

AIR HOUSING CLEARANCE

On

B48G beginning Spec

D l B43G7

and

B43E

engines the cylinder air housing to cylinder head cooling fin clearance must be checked during assembly.

The correct clearance is 0.187 to 0.313 inch (4.76 to

7.94 mm).

To

adjust cylinder air housing clearance, loosen

capscrews A and B (Figure

30).

Insert spacer tool, (a piece of

0.250 inch

[6.35

thick bar stock will work) between the cylinder head cooling fins and cylinder air housing at the points illustrated

in

Figure

30.

Tighten capscrews (A and 6) and the spacer

tool.

b b

FIGURE 30. CYLINDER AIR HOUSING CLEARANCE

10-1

8



Cummins

Power

Generation

1400 73rd Avenue

N.E.

Minneapolis, MN 55432

763-574-5000

Fax: 763-574-8087

Cummlns and Onan are registered trademarks

of

Cummins Inc.


Onan B43 E, B43 G, B48 G Engine Service Manual

Assistant Bot

965-0757

(Spec A-D)

A-D)

B48G (Spec A-G)

Service

Manual

.-

_--

Safety Precautions

result

[AWARNING!

or

to a

Is

use

of

off

Fuel

System

DO

Do

System

a

is

System

E-6

Table of Contents

TITLE PAGE

General Information

Specifications

1-1

2-1

Dimensions and Clearances

Assembly Torques and Special Tools

Engine Troubleshooting

Oil System

Fuel System

7-1

Ignition and Battery Charging

Starting

System

4-1

6-1

8-1

Engine Disassembly

9-1

10-1

AWARNING

EXHAUST GAS IS DEADLY!

THE FRESH AIR

do

of

i

General Information

INTRODUCTION

so

ENGINE

REFERENCE

by

MODEL

NO.

B

48

G G A 0 2 0 1 1 D

1 2 3 4 5 6

3.

4. Fuel required (G=gasoline).

6.

8. Specification (spec letter) which advances with

IAWARNING

1-1

,

Specifications

SPECIFICATION

Oil

UNIT OF

MEASURE

Qts

**G G A 0 2 0 1 1 D**