2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Oil leak in the weirdest place...

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Old Nov 25, 2006 | 09:55 PM
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Question Oil leak in the weirdest place...

I was pulling my intake manifold out to put this after market fuel stuff in and I notice it was extremely greasy between the upper and lower manifolds... I thought this was weird since the rest of the engine is clean other that just dirt and dust build up... I pulled the throttle body off of the upper manifold because I was going to paint it all red (Changed my mind when I saw the work involved) and this is when I realized the oil leak is coming from the black plastic spacer area between the throttle body and upper manifold...

1. Is this normal...? If yes, please go to question 2... If no please go to question 3...
2. How do I stop this leak...? Please read question 3...
3. Why the hell is there motor oil in my throttle body...??? I know motor oil is supposed to be injected into the rotor housing at some point, but I did not disconnect any oil lines from my throttle body or intake manifold that I noticed...

All help is greatly appreciated...
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Old Nov 25, 2006 | 10:15 PM
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are you sure it's engine oil?
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Old Nov 25, 2006 | 10:18 PM
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Originally Posted by mikaz
are you sure it's engine oil?
If its not, it resembled it very closely...
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Old Nov 26, 2006 | 09:48 AM
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Originally Posted by C.A.R
1. Is this normal...? If yes, please go to question 2... If no please go to question 3...
No, not really. That black plastic piece should seal against the throttle body. So yours is either not sealing or is cracked. Either way, it's going to cause a vacuum leak. You will probably have to clean the mating surface of the throttle body and intake, and inspect the plastic spacer for problems.

3. Why the hell is there motor oil in my throttle body...??? I know motor oil is supposed to be injected into the rotor housing at some point, but I did not disconnect any oil lines from my throttle body or intake manifold that I noticed...
Purge valve. The "oil" is vapour from the crankcase that is sucked into the intake manifold under vacuum. This keeps nasties and moisture from building up in the oil system.
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Old Nov 26, 2006 | 01:24 PM
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Originally Posted by Aaron Cake
No, not really. That black plastic piece should seal against the throttle body. So yours is either not sealing or is cracked. Either way, it's going to cause a vacuum leak. You will probably have to clean the mating surface of the throttle body and intake, and inspect the plastic spacer for problems.


Purge valve. The "oil" is vapour from the crankcase that is sucked into the intake manifold under vacuum. This keeps nasties and moisture from building up in the oil system.
So there being a table spoon or two of oil puddled in the throttle body is ok, but the fact it is leaking out of the throttle body is not... Is that correct...?

The little black plastic piece has very small indentions (almost un-noticeable) in it... No cracks... When I put it all back together should I use some gasket sealer around the edges to prevent leakage...?
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Old Nov 26, 2006 | 04:20 PM
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I forgot one...If the car is turbo, oil will bypass from the compressor seal and can accumulate in places as well.

Originally Posted by C.A.R
So there being a table spoon or two of oil puddled in the throttle body is ok, but the fact it is leaking out of the throttle body is not... Is that correct...?
Yes. A leak there means an intake leak, which means a vacuum leak.

The little black plastic piece has very small indentions (almost un-noticeable) in it... No cracks... When I put it all back together should I use some gasket sealer around the edges to prevent leakage...?
You can use gasket sealer but make sure not to plug any of the air passages. These are supposed to be installed dry so if yours is leaking it probably needs to be replaced.
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Old Dec 22, 2006 | 07:03 AM
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After doing some searching I found that the 3rd Gens have this problem more than anyone... They used a vented oil catch can in the place of the PCV... Turns out the line going from the oil filler neck to the PCV sucks up the oil during hard turns and it is moved through the vac lines till it gets to the TB and just accumulates there...
**
Mine just happened to be a good thing cause it revealed a vacuum leak that no one else would have ever thought to check for... I just thought I would put this in here incase anyone else thought they would do a search, there would be more than one thread shoing an answer...
**
Thanks to everyone for the answers and help...
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Old Jun 24, 2008 | 05:29 PM
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From: mcdonough,ga
i have a problem... i have an oil leak coming from the back of the motor underneath the intake manifold and i was wondering if anyone would know what it could be....
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