Oil in the Intake Tract

turbojimmy

Supporting Member
Joined
May 26, 2001
Hi all,

I'm swapping out my turbo and injectors for bigger stuff. Since I got a 4" Big Mouth kit I pulled the TB to install an angled boss for the IAC. I figured while I was at it I'd Heli-coil my doghouse bolts.

So as I'm taking all these intake parts off I noticed a decent amount of oil. At the vacuum block, on the TB blades, pooled at the front and back of the JC Power Plate, and a coating inside the lower intake. The engine has 1,300 miles on it and compression is fine and there's no crankcase pressure (from combustion, anyway). The car doesn't smoke at idle. It does smoke at WOT but it looks like fuel (black) - still trying to sort that out. Exhaust doesn't smell like oil (smells like fuel).

Plugs look good.

So what would cause this? How can I fix it? Or is some oil to be expected?

Thanks,
Jim
 
3 ways ways oil can get in the intake:
1) PCV valve, but oil would only be on the vacuum block and in the intake, not in the up-pipe or outside the throttle blades.
2) Turbo seal bad, if oil in the up-pipe, then when you do the turbo swap, that will hopefully fix it, you'll need to remove and flush out the IC also cause you don't want large amount of oil in there.
3) Or if the breather tube from the pass. side valve cover is still hooked up to the inlet side of the turbo. Remove it and cap the hole on the bell housing of the turbo and pop in a push in breather on the valve cover. You'll still need to clean the IC if this is it too. If you don't have the tube already, and oil is in the up-pipe, then its the turbo, which you are replacing anyway...
 
Originally posted by 2QUIK6
3 ways ways oil can get in the intake:
1) PCV valve, but oil would only be on the vacuum block and in the intake, not in the up-pipe or outside the throttle blades.
2) Turbo seal bad, if oil in the up-pipe, then when you do the turbo swap, that will hopefully fix it, you'll need to remove and flush out the IC also cause you don't want large amount of oil in there.
3) Or if the breather tube from the pass. side valve cover is still hooked up to the inlet side of the turbo. Remove it and cap the hole on the bell housing of the turbo and pop in a push in breather on the valve cover. You'll still need to clean the IC if this is it too. If you don't have the tube already, and oil is in the up-pipe, then its the turbo, which you are replacing anyway...

It's only in the vacuum block and in the intake. Up-pipe is clean as a whistle. No breather tube on the turbo. I have a K&N breather and it's a little oily, but nothing to write home about.

So I suppose it's the PCV. Is it bad, or is this just how it works?

Jim
 
It could be if you are getting a lot of oil. The PCV's job is to meter the crankcase gases so if you are seeing a lot of oil it may not be working correctly. I'd change it every year or so since its a $2 part.
 
Check valve will keep boost from getting into the crankcase, not oil from getting out. Just my .02.
 
I have the exact same condition that turbojimmy described. I change my AC Delco PCV every year and still have seen oil in the intake areas. I can see that a PCV check valve won't help since it's closed in the opposite direction that the oil is coming thru. It it too much crankcase pressure due to other problems ?
 
Originally posted by MistaScott
Check valve will keep boost from getting into the crankcase, not oil from getting out. Just my .02.

Yeah, I know. After reading the mixed reviews on the ATR valve I decided to stay away from it. Keeping the boost out of the crankcase (and theoretically preserving the rear seal) seemed like a good idea though.

Jim
 
Right, but the PCV should be keeping boost out anyway. The check valve is just insurance against a PCV gone bad. I wasn't trying to flame, just don't want you to throw money away.

Have you checked the intercooler for oil?
 
Originally posted by TurboSlacker
I have the exact same condition that turbojimmy described. I change my AC Delco PCV every year and still have seen oil in the intake areas. I can see that a PCV check valve won't help since it's closed in the opposite direction that the oil is coming thru. It it too much crankcase pressure due to other problems ?


If it is a LOT of oil, there is a problem. PCV vapors are likely to bring in some oil to the intake but if you are getting puddles, something is up. (There is a marathon thread on here somewhere about chasing this problem.) Check the intercooler hoses. If you find oil anywhere prior to the throttle body, it is likely from the turbo. Again, a little oil film is fine.

If crankcase pressure is excessive, something else is up (like bad rings) so try a leakdown test and compression test. Also, inspect the vent hose and grommet that goes from the intake to the passenger valve cover to make sure the filter isn't clogged. HTH
 
Originally posted by MistaScott
Also, inspect the vent hose and grommet that goes from the intake to the passenger valve cover to make sure the filter isn't clogged. HTH

Where exactly are these located? I can't picture it.
 
Before the turbo inlet bell there is a rubber hose that connects to the passenger side valve cover. That is the PCV vent, used to draw air into the system and let air out under boost. Some people got rid of theirs and use valve cover breathers instead.
 
oily intake

Try checking the condition of your turbo, and also the seal quality of those new cylinders. I know you just rebuilt the engine, and have no evidence of blowby, but you are also apparently washing the cylinders with fuel on WOT, hence black smoke. Not good for ring seal, I would think.
Do you have any intake misfiring? That will blow the oil in a turbo's bearings right past the seals. The things could just be shot, also. Usually, that leads to oil smoke from exhaust, but under high boost, all is possible...
 
Thanks for all the replies. The engine has about 1,300 miles on it so I'd think the rings should be seated by now (and sealing). There's no obvious blowby. Intercooler and turbo are squeaky clean. Inside the lower intake is just a film - no puddling there. There was a drop of oil on the inside of the throttle blades and it had puddled atop the RJC power plate at the front and back. By "puddle" it had gathered around the EGR tower and the area by the back bolt. Not dripping but wetter than a film.

I don't have an intake misfire, but it does stall on occasion when I drop it into gear. It will also sometimes stall coming off the gas quickly at highway speeds (which makes things interesting on exit ramps). Sometimes it will stall at random like I turned the key off - really weird. I've been chasing that problem since before the 2 rebuilds. I've replaced basically everything and the fargin thing still does it.

I'll keep an eye on it. I'm not sure there's much I can do about it really (other than what's been mentioned here). I'll check the other threads, too.

Thanks,
Jim
 
The little bit of oil in the intake is probably not related to the stalling. The stalling could be a bad TPS or more likely the IAC not set properly, or a bad/slow IAC. When you let off the gas and the throttle blades close, the IAC is the only thing letting air into the engine and if not open properly, will choke the air of air causing it to die. Do you have any scan tool readings when this happens or what your IAC counts are at idle in 'D'rive?

The amount of oil may be normal, I've never taken an intake off that didn't have some oil in it if there was a PCV valve installed, and there is usually enough to puddle in some places where the airflow is less in the intake tract.
 
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