Oil in the IAC ?

[The Shape]

This isn't on my car , but a friends 87 GT. It has been ideling a bit odd lately so we pulled the IAC off to clean it and it had motor oil dripping out of it! What would cause this? The engine is stock it has been smoking a bit lately, but it isn't blue like burning oil smoke normally is. If you let it idle a few minutes then rev the throttle it will blow black soot out of the pipes enough that it will leave black marks on the driveway. The plugs have quite a bit of soot on them as well, but they are not oily. Any ideas?

 

[jerry beach]

Maybe you could try changing the PCV valve. If there is motor oil in there, it has to be coming out of the tailpipes too. you prolly know there is a line going from just under the oil fill cap to the TB. This is the only supply I can think of for oil to get there. Pull that line and see if it is soaked with oil. Is the oil level correct?

 

[The Shape]

I helped him put a new PCV valve and screen in about a month ago so that should be ok. But yeah the tube from the valve cover to the throttle body is oily as well. I have seen cars with blow by before, but that much oil in the IAC seemed odd. Could that much oil be caused by the valve guide seals?

 

[bapford]

oil woes

I helped him put a new PCV valve and screen in about a month ago so that should be ok. But yeah the tube from the valve cover to the throttle body is oily as well. I have seen cars with blow by before, but that much oil in the IAC seemed odd. Could that much oil be caused by the valve guide seals?

Has the baffle been removed from the valve cover? This can sometimes lead to oil getting pulled up the tube from the filler neck at higher rpm's. If so, try a clear plastic G3 (part number) Fram fuel filter in-line between the filler neck and IAC. This is an easy indication of the amount getting in there.
The seals can pass a crazy-lot of oil if they're bad too.

 

[Black 93 Fox]

I was also gona say PVC valve.

 

[bgjohnson]

well if it's a stock motor the valves may be slightly burnt, causing a little bit of the combustion to blow by the valve and bring the pressure back up the intake or go through the seals(if they are bad). It's just an idea but I think it might help a little bit.

 

[Michael Yount]

Under high vacuum conditions (idle for example) the intake pulls air from the crankcase through the pcv. This air has to enter the engine from somewhere and it comes through the little hose running from the oil fill nipple to the throttle body - that way it's pulling air that's been metered through the maf. Under low vacuum conditions (wide open throttle) the crankcase is pressurized from blow by (even brand new engines) and this pressure gets vented through the pcv into the intake, and also through the valve cover into the throttle body. So the air moving through that hose between t/b and valve cover is bi-directional. Over time, oil mist/vapor can allow oil to accumulate in the throttle body and iab solenoid - perfectly normal. As others have suggested, be certain the pcv components are working perfectly. Pull the throttle body and iab and clean them thoroughly with carb cleaner or brake cleaner. They should work fine for many years before they need cleaning again.