Oil in air lines. 3406B

I have a n14 . The only way you could have oil in the intake supply air for compressor is if the turbo was leaking oil.
I think the oil in your compressed air is from your compressor not the air supply.

Just change your air dryer cartridge and check your compressed air for oil.

All my trucks had some oil in the compressed air. Never caused a problem that the dryer didn't clean out.

Disconnect your hoses to and from your compressor and you can see where the oil is.
Good luck

 

If you're loosing oil from your turbo into your compressor, you've still got a turbo that's beginning the end of it's life journey.

I have had that happen actually, I was replacing my air compressor, after lots of oil in the air system like you described, when I found my oil was from the line coming from the intake to the compressor.

 

Check the intake to the compressor as already mentioned to identify an engine issue feeding the compressor with oil. If the intake is dry, remove the discharge line from the compressor and hold a sheet of paper or cardboard to the charge outlet and run the compressor. If your paper get spattered the compressor is passing oil and will need replaced. Make sure it is warm when checking.

 

No , there ACTUALLY very related. The compressor gets its intake air from a #12 hose conneted to the intake manifold on a B model cat.
That same intake manifold is fed charged air from the turbo.

So yes , your air compressor is fed engine manifold pressue while engine is under load.

I don' think the oil is coming from your engine or intake. More likey the compressor is passing oil.

 

"So yes , your air compressor is fed engine manifold pressue while engine is under load" is it same on E models?

 

Yes on 99% of them. If you hear guys talking about naturally aspirated compressors that means the air compressir picks up outside air. Meaning not hooked up to the intake manifold. That system is pretty rare though.