TM 5-3805-258-24-1
L U B R I C A T I O N S Y S T E M
T E S T I N G
A N D
A D J U S T I N G
mum permissible pressure from the ENGINE
OIL PRESSURE CHART. If the pressure
reading on the test gauge is below the minimum
permissible pressure, find the cause and correct
it. Operation of the engine with low oil pressure
can be the cause of engine failure or of a reduc-
tion in engine life.
Crankcase Oil Level
Check the level of the oil in the crankcase. Add oil
if needed. It is possible for the oil level to be too far
below the oil pump supply tube. This will cause the
oil pump to not have the ability to supply enough
lubrication to the engine components.
Oil Pump Does Not Work Correctly
The inlet screen of the supply tube for the oil pump
can have a restriction. This will cause cavitation (the
sudden making of low pressure bubbles in liquids by
mechanical forces) and a loss of oil pressure. Air
leakage in the supply side of the oil pump will also
cause cavitation and loss of oil pressure. If the bypass
valve for the oil pump is held in the open (unseated)
position, the lubrication system can not get to maxi-
mum pressure. Oil pump gears that have too much
wear will cause a reduction in oil pressure.
Oil Filter and Oil Cooler Bypass Valves
If the bypass valve for the oil filter or oil cooler is
held in the open position (unseated) and the oil filter
or oil cooler has a restriction, a reduction in oil pres-
sure can be the result. To correct this problem, install
a new Caterpillar oil filter.
Too Much Clearance at Engine Bearings Or
O p e n
(Broken or Disconnected Oil Line or Passage)
Lubrication System
Components that are worn and have too much
bearing clearance can cause oil pressure to be low.
Low oil pressure can also be caused by an oil line or
oil passage that is open, broken or disconnected.
Oil Cooler
Look for a restriction in the oil passages of the oil
cooler. If the oil cooler has a restriction, the oil tem-
perature will be higher than normal when the engine
is running. The oil pressure of the engine will not get
low just because the oil cooler has a restriction.
OIL PRESSURE IS HIGH
Oil pressure will be high if the bypass valve for the
oil pump can not move from the closed position.
TOO MUCH BEARING WEAR
When some components of the engine show bear-
ing wear in a short time, the cause can be a restriction
in an oil passage. A broken oil passage can also be the
cause.
If the gauge for oil pressure shows enough good oil
pressure, but a component is worn because it is not
getting enough lubrication, look at the passage for oil
supply to that component. A restriction in a supply
passage will not let enough lubrication get to a com-
ponent and this will cause early wear.
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