Strange oily plug issue

85_SS_302_Coupe

it sucks (I know) to be on the receiving end
15 Year Member
Nov 11, 2003
6,945
1,598
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Northern KY
So, i found that every one of my plugs has oil on the threads and more so up above the threads towards the porcelin. My first and obvious suspicion is leaky valve covers, but they're spotless, as is the whole side of the heads between the plugs and the valve cover gaskets, so i don't think it's leaking from there. I do have leaky breather/PCV grommets, but again, no oil trial leading to the plugs on either side.

If this is coming from the cylinders.... then 1) how the hell is the oil getting up through the threads of a tightened spark plug?? and 2) why isn't my car smoking if that much oil is getting past the rings?

:shrug:
 
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Oh it does burn oil....it's over 250k miles....but it only smokes when i'm racing, and most cars do that anyways. It never smokes just when i'm driving around, even when i romp on it...just when i'm pounding gears at 6k.

It's the damnedest thing and it's got me totally stumped. I went out with a white terry cloth towel and rubbed the side of the heads above the plugs and it was totally clean, yet there's oil in the spark plug holes. All i can think of is maybe i have the wrong plugs, but i don't see how they still thread in and tighten down good if they're the wrong thread pattern...they thread in easy by hand. I don't see how oil could get past tightened threads either.
 
The valve seals and guides are brand new, not even 1k miles on them. My PCV is/has always leaked...i've put new valves in, nothing changes. I need to get a crank case evac setup or something...but i don't see how that coudl get getting the plugs oily. I'm gonna have to see if i can get pics of this or something.
 
I have a couple plugs that look the same way and have for the last 100k miles. My car does not burn oil and the electrods on the plugs are perfect. I have been using forced induction for the last 100k miles. I was Supercharger and now Twin Turbo and I think under boost the valve covers leak and the oil settles a little in the plug holes and when I remove the plugs to check them the oil is getting on the threads. The only thing is I can wipe down the heads and look at the exhaust manifold flange and No oil splash and no smelling of burning oil.