C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Oil issue

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Old Jul 8, 2012 | 10:30 AM
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Default Oil issue

I have a 91' L98 car. I put it up on the lift today and noticed oil coming from the rear spark plug hole on the left (drivers side) bank. Car has 49k miles, has always had semi/full synthetic. I can also smell a bit of oil if I run it for a long time. The car runs great, no bad motor noises. My first thought is bad rings, but I can't imagine a low mileage car would have bad rings, especially when it drives so well. Any ideas? Im thinking I should get it compression tested.
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Old Jul 8, 2012 | 12:15 PM
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are you sure its not from a leaking valve cover?
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Old Jul 8, 2012 | 12:30 PM
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I would agree with Deepa. The chance of oil coming out of a spark plug hole is about zero. It's coming from somewhere above the spark plug and running down and around the spark plug, giving the impression that it is coming from there.

Regards
Mac
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Old Jul 8, 2012 | 12:46 PM
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Originally Posted by okmac
I would agree with Deepa. The chance of oil coming out of a spark plug hole is about zero. It's coming from somewhere above the spark plug and running down and around the spark plug, giving the impression that it is coming from there.

Regards
Mac


If it makes you feel better take out that spark plug and have a look.

You likely have an oil leak elsewhere. Valve covers, rear of the intake and oil pressure sender are all likely culprits. If your intake has never been touched, I'll almost guarantee it's leaking.
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Old Jul 8, 2012 | 01:03 PM
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Vave cover/oil pressure sender is something I wasn't considering. The intake was recently removed and resealed when I had the injectors put in. Old plugs didn't have oil on them when headers were installed a few weeks ago, but I've been running the car pretty hard lately.
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Old Jul 8, 2012 | 01:59 PM
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I agree with the other posters. Oil doesn't come out of spark plug holes. It is most always the valve cover which leaks oil that puddles around the spark plug.
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