Lubricating Oil System Diagnostics (007-048)
B3.9 and B5.9 Series Engines
Section 7 - Lubricating Oil System - Group 07
Another remote possibility, is that a crack or porosity in the
head casting could allow fuel to leak to the air intake and
onto the cylinders.
Lubricating Oil System Diagnostics
Lubricating Oil Pressure Regulating Valve
The engine will have high oil pressure at normal operating
temperature if the regulator sticks in the closed position.
Check the regulator for freedom of movement.
Refer to Procedure 007-029.
Low-Lubricating Oil Pressure
Low-lubricating oil pressure (or no oil pressure) can be
caused by several lubrication system related malfunctions.
To begin the investigation, determine the engine operating
conditions when the low-pressure was first observed; i.e.,
following a service interval, at idle only, and while oper-
ating on a steep grade.
Lubricating Oil Level
High oil level can cause low oil pressure. If the oil level is
high enough for the connecting rods to dip into during
operation, the oil can become aerated, resulting in low oil