B3.9 and B5.9 Series Engines
Section 7 - Lubricating Oil System - Group 07
Use the following logic to determine the source of the oil
dilution with fuel:
A worn or damaged fuel injection pump shaft seal will allow
fuel to leak into the gear housing and then into the lubri-
cating oil pan.
The seal is designed to provide increased sealing as the
pump case pressure increases. Pressure forces the lip (1)
tighter around the shaft.
A worn seal could leak during start-up and shutdown when
case pressure is low. A worn seal can not easily be de-
tected by pressurizing the pump.
The bushing (2) in the Bosch VE fuel injection pump can
cause a seal leak. If the bushing is loose in the housing,
it will move toward the seal raising the lip (1) and providing
a leak path for fuel.