Onan NHC Series Operator's/Service Manual And Parts Catalog page 310

GEAR COVER
O I L SEAL
AS 77
Use haavy fibar or
cup grease in spac*
between seals to
improve
REAR BEARING P L A T E
• MOUNTING F A C E
OF GEAR COVER
I 1/32
THIS SURFACE SHOULD BE
C L E A N E D OF A L L OLD
SEALING COMPOUND BE-
FORE I N S T A L L I N G SEAL.
- T H I S SURFACE SHOULD BE
C L E A N E D OF A L L OLO
SEALING COMPOUND BE-
FORE I N S T A L L I N G S E A L .
DRIVE OR PRESS OIL
SEAL TO SHOULDER
OF THE P L A T E BORE
GEAR COVER O I L SEAL
REAR BEARING P L A T E
O I L SEAL
FIGURE 63. GEAR COVER AND REAR BEARING PLATE OIL SEALS
OIL SEALS
The bearing plate must be removed to replace its oil
seal. Drive the oil seal out from the inside using
bearing plate driver and gear cover driver.
Before installing the seals, fill the space between
seals with a fibrous grease or stiff cup grease. This will
improve sealing. See Figure 63.
When installing the gear cover oil seal, tap the seal
inward until it is 11/32 of an inch from the mounting
face of the cover.Mnstall new style, thin open face seal,
1-7/64 inches from mounting face of 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 shim stock around the end of the
crankshaft, when replacing the bearing plate to avoid
damaging the seal. Remove the shim stock as soon as
the plate is in place.
Engines equipped with some types of reduction gear
assemblies do not use the rearoil seal. The reduction
gear assembly is oiled directly from the engine
crankcase. Refer to the instructions screened on the
case of the reduction gear assembly.
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 accom-
modate 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 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 E following the engine serial number stamped,
on the cylinder block and on the unit nameplate.
The standard cylinder bore size appears in;
Dimensions and Clearances.
OIL PUMP
To remove the oil pump, it is necessary to detach the - '
intake cup assembly as shown in Figure 64.
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.
OIL PUMP INT AK
CRANKCASE TURNEDjft
ON LEFT SIDE— y
UNSCREW OIL PUMP ASSEMBLY
FROM INTAKE CUP AT THIS POINT
To reassemble reverse the procedure.
O I L PUMP ASSEMBLY-*
FIGURE 64. OIL PUMP ASSEMBLY
41
9 0 2 4 0 7