Onan NHC | NHCV Engine Service Manual

Onan NHC | NHCV Engine Service Manual
Service Manual
NH & NHC
Industrial Engines
Service Manual
Onan
THIS IS A MANUAL PRODUCED BY JENSALES INC. WITHOUT THE AUTHORIZATION OF
ONAN OR IT’S SUCCESSORS. ONAN AND IT’S SUCCESSORS
ARE NOT RESPONSIBLE FOR THE QUALITY OR ACCURACY OF THIS MANUAL.
TRADE MARKS AND TRADE NAMES CONTAINED AND USED HEREIN ARE THOSE OF OTHERS,
AND ARE USED HERE IN A DESCRIPTIVE SENSE TO REFER TO THE PRODUCTS OF OTHERS.
ON-S-NH,NHC
O~ERAT()iRS/SERVICE .MANUAL
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940-402
Prlnled in V.S.A.
1AD73
ONAN
INDUSTRIAL ENGINES
NH
SERIES
TABLE OF CONTt:NTS
PAGE
TITLE
General Information
Specifications . . .
Dimensions and Clearances
Assembly Torques and Special Tools
Troubleshooting
Installation . . . . . . .
Operation . . . . . . . .
Service and Maintenance
Adjustments . . . . . . .
Fuel System . . . . . . .
Ignition and Battery Charging Systems
Starting System . . .
Oil System . . . . .
Engine Disassembly
Parts Catalog .
Wiring Diagrams . . .
1
2
3
4
6
7
8
11
12
15
21
25
30
37
38
47
66
(SHOWN WITHOUT
ENGINE CONTROL)
MOVE GOVERNOR SPRINGSLIDE
ASSEMBLY
/
GOVERNOR
SHAFT
GOVERNOR ARM EXTENSION
DETENT SPRING
(Optional) For locking
at minimum speedo
MAXIMUM SPEED STOP
FIGURE 17. VARIABLE SPEED GOVERNORS
the speed (Figure 16).
are adapted for use where a wide range of s peed settings
is desired. The design of the variable speed governors
gives an automatic increase in sensitivity when the
speed is increased and the result is good stability at
all speeds.
SENSITIVITY ADJUSTMENT
The engine speed drop from no load to full load should
be not less than 100 rpm. Check the engine speed
with °no load connected and again after connecting
full load. Do not exceed 4000 rpm at no load.
To adjust the variable speed governors, refer to Figure
17 and the following:
The sensitivity of the governor depends upon the
position of the arm end of the governor spring. A
series of holes in the governor arm provides for adjustment. To increase sensitivity, move the spring
toward the governor shaft. To decrease sensitivity,
move the spring toward the linkage end of the governor
arm.
1. Run the engine and make necessary. carburetor
adjustments.
2. Adjust the throttle stop screw on the carburetor to
allow a recommended minimum idling speed of
900 rpm. A lower minimum does not assure smooth
operation under load.
3. Adjust the tension of the governor spring for minimum speed. For the control with the control arm,
shift the lever to minimum speed with no load and
adjust the spring tension for approximately 1500
rpm.
If the setting is too sensitive, a hunting condition
(alternate increase and decrease in engine speed) will
result.
If the setting is· not sensitive enough, the
speed variation between no load and full load conditions will be too great. Therefore, the correct sensitivity will result in the most stable speed regulation
without causing a surge condition.
For the control with the control knob and slide (NH
engines with mounted engine controls), pull back
the knob and slide and set at the first notch (low
speed). Adjust speed to approximately 1500 rpm
(or the desired low speed) at no load by turning
the knob as required.
4. Adjust the sensitivity while operating at minimum
speed to attain the smoothest no load to full load
operation as follows:
Always recheck the speed adjustment after a sensitivity
adjustment. Increasing sensitivity will cause a slight
decrease in speed and will require a slight increase
in the governor sl'ring tension.
Variable Speed Governor Adjustments: TheSe engines
18
Use heavy fiber or
cup grease in space
between seals
to
improve seal. - -......""'"4~
GEAR
COVER
REAR BEARING PLATE
MOUNTING FACE
OF GEAR COVER
THIS SURFACE SHOULD
BE CLEANED OF ALL
OLD SEALING COMPOUND BEFORE INSTALLING SEAL.
OIL SEAL
Asn
THIS SURFACE SHOULD
BE CLEANED OF ALL
OLD SEALING COMPOUND BEFORE INSTALLING SEAL.
DRIVE OR PRESS OIL
SEAL TO SHOULDER
OF THE PLATE BORE
REAR BEAruNG PLATE
OIL SEAL
GEAR COVER OIL SEAL
FIGURE 68. GEAR COVER AND REAR BEARING PLATE OIL SEALS
Check the oil pump thoroughly for worn parts.
Oil
the pump to prime it before reinstalling. Except for
gaskets, the component parts of the pump are not
available individually. The suction cup is available
separately. Install a new pump assembly, if required.
CYLINDER
The cylinder wears very little in normal service. If,
through improper lubrication or accident, the cylinder
wall should become scored or worn badly, the cylinder
may be rebored and honed to accommodate a new
piston and ring set of the available oversizes. Pistons
are available in .005 ", .010 ", .020", .030" and .040"
oversize. Piston rings are available in .010 ", .020 ",
.030" and .040" oversize. Use standard size rings
on a .005" oversize piston. If the cylinder is not
being reconditioned, but new piston rings are being
installed, remove any ridge which may have become
formed at the top of piston ring travel in the cylinder
bore.
Engine might be fitted at the factory with a
.005" oversize piston and are so indicated by a letter
FIGURE 69. OIL PUMP ASSEMBLY
E following the engine serial number stamped on the
cy Hnder block and on the unit nameplate.
The standard cylinder bore size appears in Dimensions
and Clearances.
46
IGNITION GROUP
13--1
I
r
I
I
9
12-1
I
I
I
I
~----
I
7---..,
I
I
I
I
I
L_~ .~
15
25
REF.
NO.
--
PART
NO.
QTY.
USED
10
II
12
13
160A930
160AI50
160A75
160A2
312A69
160AI040
160A723
160AI143
CABLE, SPARK
167AI464
167AI548
166B535
167AI463
167-241
160AI135
14
15
509-35
160A428
16
160A349
I
2
3
4
5
6
7
8
9
REF.
NO.
PART
DESCRIPTI()N
Co ver, Break er Box
Gasket, Breaker Box Cover
Cam, Point Gap Adjusting
Point Set, Breaker
Condenser, Breaker Points
Gasket, Breaker Box Mounting
PI unger
I
Diaphragm, Breaker Box
PLUG - RIGHT HAND
Key 2 (24 0)
I
Key I (21°)
I
Coil, Ignition, Key 2
I
Cable (19"), Spark Plug- L.H.
I
Plug, Spark
2
Box, Breaker (Includes Points,
I
Condenser Cover, Gasket &
Bushing)
"0" Ring - Spark Plug Cables
Strap, Point Set to Terminal
Block
BI'ock & Terminal Assembly
'59
PART
NO.
23
24
25
26
27
332A273
GROMMET
508A2
508P 114
508P95
313-18
160BI121
16001124
160BII18
167AI88
160AI041
I 60A26 I
815P357
166B519
28
308AI40
29
30
302A60
338A613
31
160A93I
17
18
19
20
21
22
QTY.
USED
PART
DESCHIPTION
CI ip, Magneto Lead, Key
I
I
2
4
I
I
2
I
Magneto Lead Clip, Key I
Ignition Coil Lead, Key 2
Spark Plug Cables
Switch, Ignition Stop, Key
Magneto Stator Assy., Key I
Coil, Magneto Stator, Key I
Pole Shoe, Magneto Stator, Key I
Clip, Spark Plug Cables, Key I
Bushing, Breaker Box (Bottom)
Wi ck, Breaker Box
Screw, Mounting - Breaker Box
Bracket, Timing - Vacu-Flo
Cooled Engines
Switch, Toggle - Ignition (StartOn-Off) - Optional
Ammeter, DC (20-0-20) - Opt.
Harness, Wiring - Ammeter to
Terminal Block - Optional
Guide. Plunger
SPECIFICATIONS
NHC-MS/l
Number of Cylinders . • . •
Displacement (cubic inch) .
Cylinder Bore
Piston Stroke . • •
Horsepower • • . •
Compression Ratio . • • • . . . . . .
Ventilation Required (cfm @3600 rpm) .
Oil Capacity • • . • • . • • • .
Oil Capacity With Filter Change
Starting . . • • • • • • • . • • .
Ignition . . • . . • • . • . • . •
Combustion Air (cfm @3600 rpm)
Fuel . . • .
Fuel Pump . . . • . . • • . . . .
2
60
3-9/16 in.
3 inch
25 BHP @3600 rpm
7.0 to 1
1080
3-1/2 qt.
4 qt.
Electric
Battery
80
Gasoline (regular grade)
Diaphragm, 4 ft. lift
TUNE-UP SPECIFICATIONS
Spark Plug Gap . • . .
Breaker Point Gap . . .
Ignition Timing (Fixed),
Tappets (Cold) Intake •
Exhaust
. • . . . . . . .
• . . . . . . . .
Electric Start Units
.025 "
.020 "
25°BTC
.003 "
.012 "
.••.•...•..
NOT E: For gaseous fuel operation set spark plugs at .018" and ignition timing at 26°BTC and exhaust valve
lash at .014".
3
STARTING SYSTEM
ELECTRIC STARTER REPAIR
l"'"::~
Do not use steam or high pressure
~ water to c/eim the starter.
'---_._---_..
FIGURE 28.
3.
FIGURE 26.
STARTER ASSEMBLY
REMOVING THROUGH BOLTS
The armature can easily be removed from the front
bracket. Be careful not to miss a small steel
washer used in the end of the armature shaft. The
shift lever can be removed along with the armature
when it is removed. In this case, the spring holder.
lever springs and retainer can be taken out before
the lever. See Figure 29.
DISASSEMBLY
1. Loo,.;en the M terminal nut on the magnetic switch
and remove the connector. Then unscrew attaching
screws and remove the magnetic switch.
NOTE: ThL' packings
[or the magnetic switch are
mOlInteel so thot the steel packing is located in the
[ront bracket side.
I
~
_ _ _J
f"IGURE 29.
26
REMOVING ARMATURE
4.
Remove the ring after driving the pinion stopper
toward the pinion gear using a cylindrical tool
as shown in Figure 30. The ovenunning clutch
and the pinion stopper should be removed simultaneously.
5.
All four brushes have been soldered to the brushholder in the same way. The brush springs can
be removed from the brushholder.
6.
The pole shoes may be removed if necessary, by
removing the flat head machine screws from the
frame.
FIGURE 27. MAGNETIC SWITCH REMOVAL
2. After removing the thru bolts, the starting motor
can be divided into three parts - the front bracket,
housing and rear bracket. The spacing washers
shown in Figure 28 are used for adjustment of
the thrust gap of the armature shaft and are placed
between the rear bracket and the commutator.
NOTE: These washers are inserted so the steel
washer is located in the commutator side.
I
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