Onan MCCK Series User Manual

Oil System
*
The engine has pressure lubrication to all working
parts. The oil system includes:
Gear type oil pump
Oil pressure gauge
Oil passages to deliver oil throughout.
Oil filter (if used)
I Oil intake cup
engine
Crankcase pressure could blow out
I-) hot oil and cause serious burns. Do
NOT check oil while the engine is operating.
The oil pump is located on the front surface of the
crankcase and is driven by the crank gear. The inlet
pipeand screen assembly attach directlytothe pump
body. Figure
19. A discharge passage in the cover of
the pump registers
with a drilled passage in the
crankcase. Parallel passages distributeoil to the front
main bearing, rear main bearing, and pressure con-
trol bypass valve.
Circumferential grooves in the main bearings supply
oil to the 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. The flyball
governor
is lubricated byadrilled passage in thefront
camshaft journal.
Normal oil pressure should be
30 psi (207 kPa) or
higher when the engine isatoperating temperature.
If
pressure drops below 30 psi (207 kPa) at governed
speed, inspect the oil system for faulty components.
__
OIL PUMP INTAKE CU
ON LEFT SIDE +
OIL PUMP ASSEMBLY;
FIGURE 19. OIL PRESSURE PUMP ASSEMBLY
OIL BYPASS VALVE
The by-pass valve (located to 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
30 psi (207 kPa).
The
oil overflow from the bypass valve furnishes
lubrication to the camshaft drive gears.
The valve is non-adjustable and normally needs
no
maintenance. To determine if abnormal (high or low)
oil pressure is caused by a sticky plunger inspect as
f 01 lows:
1. Remove 3/8 x 24 x 3/4 cap screw located behind
gear cover and under governor arm.
2. Remove spring end plunger with a magnet tool.
Clean plunger and spring with
a suitable solvent
and install.
FIGURE 20. OIL PRESSURE
33
Redistribution or publication of this document
by any means, is strictly prohibited.
Redistribution or publication of this document
by any means, is strictly prohibited.

Onan MCCK Series Specifications

General

Cylinders	2
Fuel Type	Gasoline
Governor Type	Mechanical
Starting	Electric
Lubrication System	Pressure
Rotation	Counterclockwise
Bore	3.25 in. (82.6 mm)