Figure 6-32.Full force-feed lubrication system.
to the piston pin bearing. This passage not only feeds
the piston pin bearings but also provides lubrication for
the pistons and cylinder walls. This system is used in
virtually all engines that are equipped with full-floating
LUBRICATING SYSTEM PROBLEM
To troubleshoot an engine lubricating system, begin
by gathering information on the problem. Ask the
operator questions. Analyze the symptoms using your
understanding of system operation. You should arrive
at a logical deduction about the cause of the problem.
The four problems most often occur in the
lubrication system are as follows:
1. High oil consumption (oil must be added
2. Low oil pressure (gauge reads low, indicator
light glows, or abnormal engine noises)
3. High oil pressure (gauge reads high, oil filter
4. Defective indicator or gauge circuit (inaccurate
operation or readings)
When diagnosing these troubles, make a visual
inspection of the engine for obvious problems. Check
for oil leakage, disconnected sending unit wire, low oil
level, damaged oil pan, or other troubles that relate to
High Oil Consumption
If the operator must add oil frequently to the engine,
this is a symptom of high oil consumption. External oil
leakage out of the engine or internal leakage of oil into
the combustion chambers causes high oil consumption.
A description of each of these problems is as follows:
External oil leakagedetected as darkened oil
wet areas on or around the engine. Oil may also
be found in small puddles under the vehicle.
Leaking gaskets or seals are usually the source of
external engine oil leakage.
Internal oil leakageshows up as blue smoke
exiting the exhaust system of the vehicle. For
example, if the engine piston rings and cylinders
are badly worn, oil can enter the combustion
chambers and will be burned during combustion
Do not confuse black smoke (excess fuel
in the cylinder) and white smoke (water
leakage into the engine cylinder) with blue
smoke caused by engine oil.