Lift Pump Leakage; Cylinder Head Leakage; Oil Leaks - Dodge D250 1990 Service Manual

Engine Lubricating System
Page9B-12
Base Engine Components
DODGE Turbo Diesel
j^j^ Lift Pump Leakage
There is a remote possibility for fuel to drain into the oil from
the lift pump.
For this to happen, the diaphragm in the pump would have to
break and the drain hole would have to be plugged.
Cylinder Head Leakage
Another remote possibility, is a crack or porosity in the head
casting could allow fuel to leak to the air intake and on to the
cylinders.
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A blown cup plug can allow a relative large quantity of oil to
escape resulting in a sudden drop in the oil pressure.
When checking for such a leak, be sure to check the plug
behind the tappet cover as well as those that may be obscured
by chassis parts.