Oil on spark plugs

BriceJohnson · **Joined:** Thu Apr 13, 2006 7:33 am **Posts:** 2230

Changed the plugs in the 3 the other day, and was a little worried to find some oil on the plugs in cylinders 2 and 4 (but nothing in 1 and 3). I know its a vague symptom, but any idea what this could be or whether its something to worry about? I know the 3 is notorious for failing PCV's (although I honestly don't really know what a PCV does). Any help would be greatly appreciated. The engine is showing no symptoms other than that, pulls as strong as it always has, it had picked up a little stumble at idle (which is why I changed the plugs), but its something that developed gradually, I figured 85k miles, it was just time for new spark plugs. CHanging the plugs has made the stumble go away, but I'd hate to see oil come back and foul the plugs (they aren't particularly cheap plugs).

BretLuter · **Posted:** Fri Aug 08, 2008 9:33 am

PCV= Positive Crankcase Ventilation

Basically it's a check valve, usually in the crankcase or valve cover breather hose, that allows oily fumes from the crankcase to get sucked back into the engine and burned via the intake or intake plumbing.

85k is not a bad plug interval, I wouldn't worry too much about it. If you're still concerned, drive ~10k and then pull all the plugs and see what they look like. If they're fouled, you can clean them with carb cleaner instead of replacing them, if the electrodes, etc are in good shape.

Bret.

BriceJohnson · **Joined:** Thu Apr 13, 2006 7:33 am **Posts:** 2230

so seeing some oil on the plugs is no big cause for concern with that mileage? I would think that I'd see burnt up oil, not actual wet oil on them. It WAS just on the threads though, there was very little oil actually on the electrode or anything.

BretLuter · **Posted:** Fri Aug 08, 2008 9:45 am

Are the plugs recessed into the head? If there's no oil on the electrode, then you have an external oil leak- probably a leaky valve cover gasket.

Oil leaks/seeps out of the valve cover gasket, then runs down into the spark plug hole and pools around the plug, just up from the threaded part. THAT's where your oil is coming from, I'll bet........

BriceJohnson · **Joined:** Thu Apr 13, 2006 7:33 am **Posts:** 2230

hmm, you may be right. Come to think of it, the porcelain (I think its porcelain, the white part) of the plug is discolored brown too. Thanks for your help.

THSCC Forums

Oil on spark plugs

Who is online