B3.9 and B5.9 Series Engines
Section 7 - Lubricating Oil System - Group 07
During operation, the lubricating oil pressure will be higher
than coolant pressure. A leak in the lubricating oil cooler
will show as lubricating oil in the coolant.
However, following an engine shutdown, the residual pres-
sure in the coolant system can cause coolant to seep
through the leak path into the lubricating oil.
To check for leaks, pressurize the cooling system to 140
kPa [20 psi]. With the system pressurized, remove the
following components, and inspect for leaks.
· Valve covers (leaks indicate cracked head)
· Lubricating oil drain plug (leaks indicate defective
lubricating oil cooler, head gasket, cracked head or
· Tappet cover (expansion plug leak).
Coolant in the lubricating oil can be caused by a damaged
cylinder head gasket or cracked cylinder head or block.
Remove the cylinder head and gasket, and inspect for
cracks or damage.
Fuel-Diluted Lubricating Oil
Fuel dilution is limited to five sources:
1. Injection pump shaft seal
2. Fuel leaking by the rings
3. Fuel transfer pump
4. A crack in the cylinder head from the fuel filter location
to the air intake
5. Injector leakage.