Various gaskets, seals and plugs are used to contain the lubricating oil. Most leaks can be identified during routine
inspection of the engine and vehicle.
A blown expansion plug can allow a relatively large quantity of lubricating oil to escape resulting in a sudden drop
in the lubricating oil pressure.
When checking for such a leak, be sure to check the expansion plug behind the tappet cover as well as those
that may be obscured by chassis parts.
Lubricating oil blowing out the breather is a good sign of a blown expansion plug. This is usually more obvious on
a four cylinder engine.
If the lubricating oil cooler element ruptures, the lubrieating oil pressure will force lubricating oil into the coolant
system. Lubricating oil in the coolant should be visible when the radiator cap is removed.
Refer to page 2-18 for lubricating oil cooler element replacement and testing.
Worn or damaged seals in the turbocharger can also allow lubricating oil to leak into the air crossover pipe and
be burned in the engine.
The condition can be verified by removing the air cross over tube or charge air cooler tubing and looking for oil.
Inadequate sealing of the piston rings will result in lubricating oil being blown out the breather tube and/or consumed by the engine (refer to the Base Engine Components Section for measuring blow-by).
Lubricating oil can also be lost through a worn or malfunctioning air compressor. Look for carbon build up in
the air line from the compressor to the air tank. Also, a failed air compressor head or head gasket can allow oil
to leak into the coolant or coolant to leak into the oil during hot shutdown.
