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Old 10-31-2008, 03:43 AM   #1
karst
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Default Oil on air filter AND spark plug boots

I discovered oil on my air filter and all four spark plug boots (small oil deposits in plug holes but no major pooling). Are these most likely related, from 'blow-by'? If so, am I right that it isn't worth changing valve cover gaskets? Is there another probable suspect (my PCV valve is only a couple years old).

In case it matters, I found these while troubleshooting a rough idle, which was fixed with a new o2 sensor, but I also replaced oil, air & fuel filters, plugs & wires, and applied upper throttle body cleaner and manually cleaned IAC.
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Last edited by karst; 11-01-2008 at 12:52 AM.
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Old 10-31-2008, 05:51 PM   #2
Subyroo2.5
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Oil would not get passed your spark plugs, even if you have a blow-by condition.
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Old 10-31-2008, 06:51 PM   #3
GrundleJuice
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lots of down shifting, especially to higher rpms, can work oil up the breather lines pretty easily from my experience.
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Old 10-31-2008, 09:39 PM   #4
karst
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Thanks guys. It sounds like the two may not be related then. In that case I guess I should try the most likely fix for an oil leak into the plug holes, and replace my valve cover gasket and plug seal rings. Judging from the look of my old plugs it doesn't look like oil made it past the threads:



http://img265.imageshack.us/my.php?i...resizedld6.jpg

I don't know what to do about the oil hitting the air filter. I could replace my PCV valve again. I read that a collapsed vacuum line is another common cause, but I'm not even sure what that would look like. My hoses look and feel okay at least. Here is what my old filter looked like:



http://img265.imageshack.us/my.php?i...resizedra2.jpg
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Old 10-31-2008, 10:32 PM   #5
Subyroo2.5
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wow thats a lot of oil on that filter.
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Old 10-31-2008, 10:43 PM   #6
GrundleJuice
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how many miles on that air filter? my oem filter had a similar pattern of filth after 6k miles, but it wasn't oil, just dirt, and not as dark.
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Old 11-01-2008, 12:46 AM   #7
karst
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Yeah, that was my reaction when I pulled out the air filter.

It had 10,500 miles on it. The last used air filter I replaced did not look as bad -- it was certainly dirty but no oil splotches. I guess I should keep my eye on the new one I just installed for a while.

I don't know if it could possibly be related but for the last couple months I was getting a surging idle and the odd strange noises from under the hood, until I did the work mentioned above (o2 sensor fixed the unstable idle). Engine sounds much better now.

If anyone has suggestions for fixing or monitoring, apart from a valve cover gasket+ and maybe PCV replacement, please let me know.
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