5-8 LUBRlCATlON SYSTEM
Pressurized Lubrication System
The engine lubrication circuit is a pressurized system consisting of a
positive displacement pump which picks up oil through a filter screen
from the crankcase. The oil is pumped to a replaceable oil filter cartridge,
through the engine’s oil passages lo lubricate internal components, and
return to the crankcase. A bypass valve is incorporated in the oil filter to
allow oil to circulate if the filter becomes clogged. A pressure relief valve
is used between the oil pump and oil filter to relieve excessive oil pressure
by returning excess oil to the crankcase (see Oil Flow Chart).
Oil Pressure Measurement
l Remove the oil pressure switch (A) from the crankcase.
@Install an appropriately sized oil pressure gauge adapter and
pressure gauge.
l Run the engine ‘and allow warrn
up
completely.
l Run the engine ,at fast idle speed and read the oil pressure gauge.
l
Stop the engine.
0 Remove the oil pressure gauge and adapter.
*Apply a non-permanent locking agent to the taper threads of
pressure switch and install the switch.
*If the oil pressure is below the specification, inspect the oil pump
relief valve.
oil
the
and
*If the oil pump and relief valve are not at fault, inspect the rest of the
lubrication system.
Oil Pressure (Ylnlmum)
276 kPa (40 psi)
011 Pressure Swlkh
PT 118 (Taper Pipe Threads)
Oil Pressure Switch Inspection
When the oil pressure falls below 98 kPa (14.2 psi), the oil pressure
switch activates the oil warning lamp to alert the operator or lubricating
problem.
*To check the oil warning system, insert the switch key into the “OFF”
position of the engine switch, the’n turn it to the “RUN” position. The
warning light must be illuminated.
@Whenever start the engine, make sure the warning light is not on in
started engine.
*If the warning light comes on, stop the engine immediately and check
the oil level.
l
When starting the engine, note the warning light on dash carefully.
*If the warning light is on in the started engine in spite of adequate oil
level, check the laad from the pressure switch to the warning light for
short circuit and/or check the pressure switch and replace damaged
part.
*If the light is not on al: the moment of the engine switch operation,
check all leads of the warning light circuit or bulb and replace damaged
parts.
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