TM 5-3825-226-24
5P6225 HYDRAULIC TEST BOX
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 result in the oil
pump not having the ability to supply enough lubrication
to the engine components.
Oil Pump Does Not Work Correcty
The inlet screen of the supply tube for the oil
pump can have a restriction. This will result in
cavitation 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 pressure regulating valve
for the system is held in the open (unseated) position,
the lubrication system can not get to maximum
pressure. Oil pump gears that have too much wear will
cause a reduction in oil pressure.
Oil Filter and Oil Cooler
A dirty oil filter will cause a reduction in oil
pressure. When the oil filter is filled with dirt, a
restriction of oil flow thru the filter and a reduction of
filtered oil pressure is the result.
The bypass valve will cause the flow of oil to go
around the filter elements when there is a reduction to
the flow through the elements. When the bypass valve
is open, oil that is not filtered is permitted to flow thru
the engine. To correct this problem, install a new
Caterpillar filter.
Look for a restriction in the oil passages of the
oil cooler. If the oil cooler has a restriction, the oil
cooler bypass valve in the oil filter base will open. This
will cause the flow of oil to go around the oil cooler. The
oil temperature will be higher than normal when the
engine is running. The oil pressure of the engine will
become low if the oil cooler has a restriction.
Too Much Clearance at Engine Bearings or Open,
Broken or Disconnected Oil Line or Passage in
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 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 COMPONENT WEAR
When some components of the engine show
bearing wear in a short time, the cause can be a
restriction in the oil passage. A broken oil passage can
also be the cause.
If the gauge for oil pressure shows the correct
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
component and this will cause early wear.
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