Oil
System
'Onan diesel engines have pressure lubrication to alp
working parts of the engine. The oil system includes
an oil intake cup,
a
gear-type oil pump, a by-pass
valve, a full-flow oil filter and passages and drillings
through the block for oil delivery.
;
Figure
36
shows the pressure oil system.
A
thin film of oil from the crankcase IubricateS the
cylinder walls and the rings wipe the excess oil off to
prevent passage of oil to the combustion chamber.
The upper portion of the cylinders are partially
lubricated by the fuel. The connecting rod bearings
are critically
in
need of lubrication because of the
high pressures and high rotating speeds. Bearing
lubrication and cooling are very important to the life
of an engine.
Normal
oil
pressure should be 25.psi (172.5 kPa) or
higher when the engine is at operating temperature. If
pressure drops below 20 psi
(138
kPa) at governed
speed, inspect the oil system for faulty components.
BY-PA
VALVE
-FILTER
LS-1013
FIGURE
36.
OIL
PRESSURE
SYSTEM
OIL
PUMP
The oil pump is mounted on thefront of the crankcase
gear.
Repair
are not individuallv available. If the Dump is defective
behind the
gear
'Over
and
is
driven
by
the
crankshaft
Except for the gaskets, component parts of the pump
The pump draws oil from the crankcase and delivers it
through the
oil
filter to the rocker housing, drillings
through the crankcase to the crankshaft bearings,
camshaft front bearing, crankshaft passages to con-
necting rod bearings and connecting rod passages to
piston pin bushings.
Rem oval
or excessively worn, replace
it.
'Disassemble the
pump by removing the two cap screws holding the
pump cover to the body. Inspect forexcessive wear
in
gears and shafts.
To
improve pump performance,
adjust the gear end clearance by changing the gasket
thickness between the pump body and cover. Use the
thinnest gasket that permits free movement of the
pump shafts. Oil all parts when assembling the pump.
Installation
engine and adjust the 0.005-inch (0.127 mm) lash
1.
Remove gear cover and oil base. (See
ENGINE
2. Unscrew intake cup from pump.
DISASSEMBLY.
Before installing, fill the pump intake and outlet with
oil to be sure it is primed. Mount the pump on the
between the pump gear and crankshaft gear. Mount
4.
Loosen two cap screws holding pump and the intake cup on the pump
so
it
is parallel to the
bottom of the crankcase.
3.
hemove crankshaft lock ring and gear-retaining
I
was her.
remove pump.
36
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