Air Compressor

What do you mean the air compressor is leaking oil into the cab?

If you mean the one on the engine that provides the brakes with air, it needs to be replaced.

 

If we're talking about a class 8 truck, and some type of oil is coming into the cab, that can't be good. Regardless, sounds like an issue that needs to be addressed.

 

First off, drain your air tanks. Put a drip tray or bucket under them and drain all of them completely. No oil in the air tanks, compressor is likely ok.

Second, is this an older truck with a mechanical oil pressure gauge? If it is, I bet that's the issue. They plumb that gauge into the engine lube system. If that hose to the gauge, a fitting or the gauge itself leaks it'll pump engine oil out into the cab.

 

How would an air compressor leak anything into the cab?

 

Maybe he means theres oil leaking from parking brake valves?

 

If that's the case, there would be oil in the air tanks. And the air dryer would be pooched too.