Oil Leakage Into Combustion Area of Cylinders

LUBRICATION SYSTEM

TESTING AND ADJUSTING

LUBRICATION SYSTEM

Gauge, which is part of 7S8875 Hydraulic Test Box, can

One of the problems in the following list will generally

be used for checking pressure in the system.

be an indication of a problem in the lubrication system for

the engine.

TOO MUCH OIL CONSUMPTION

OIL PRESSURE IS LOW

OIL PRESSURE IS HIGH

TOO MUCH COMPONENT WEAR

TOO MUCH OIL CONSUMPTION

Oil Leakage on Outside of Engine

7S8875 HYDRAULIC TEST BOX

Check for leakage at the seals at each end of the

crankshaft. Look for leakage at the oil pan gasket and all

Crankcase Oil Level

lubrication system connections. Check to see if oil is

coming out of the crankcase breather. This can be caused

Check the level of the oil in the crankcase. Add oil if

by combustion gas leakage around the pistons. A dirty

needed. It is possible for the oil level to be too far below

crankcase breather will cause high pressure in the

the oil pump supply tube. This will result in the oil pump

crankcase, and this will cause gasket and seal leakage.

not having the ability to supply enough lubrication to the

engine components.

Oil Leakage Into Combustion Area of Cylinders

Oil leakage into the combustion area of the cylinders

Oil Pump Does Not Work Correctly

can be the cause of blue smoke. There are three possible

ways for oil leakage into the combustion area of the

The inlet screen of the supply tube for the oil pump

cylinders:

can have a restriction. This will result in cavitation and a

loss of oil pressure. Air leakage in the supply side of the

1. Oil leakage between worn valve guides and valve

oil pump will also cause cavitation and loss of oil

stems.

pressure. If the pressure regulating valve for the system is

held in the open (unseated) position, the lubrication

2. Worn or damaged piston rings or dirty oil return

system can not get to maximum pressure. Oil pump gears

holes.

that have too much wear will cause a reduction in oil

pressure.

3. Compression ring not installed correctly.

Oil Filter and Oil Cooler Bypass Valves

Too much oil consumption can also be the result of

using oil with the wrong viscosity. Oil with a thin (low)

If the bypass valve for the oil filter is held in the open

viscosity can be caused from dirt or fuel getting in the

position (unseated) and the oil filter has a restriction, a

crankcase, or by the engine getting too hot.

reduction in oil pressure can result.

OIL PRESSURE IS LOW

The bypass valve is in the oil filter base. The bypass

valve will cause the flow of oil to go around the filter

An oil pressure gauge that has a defect may give an

elements when there is a reduction to the flow through the

indication of low oil pressure.

elements.

When the engine is running at rated speed with SAE 30

oil at operating temperature, the oil pressure measured at

If the oil cooler has a restriction:, the oil cooler bypass

the clean side of the oil filter at the oil filter base will be 55

valve in the oil filter base will open. This will cause the

to 85 psi (3.9 to 6.0 kg/cm2 ).

flow of oil to go around the oil cooler.

A minimum low pressure reading of 15 psi (1.1

kg/cm2) is normal at low idle rpm. If there is no oil

pressure, stop the engine immediately. An 8M2744