Oil on Spark Plugs

This discussion was created from comments split from: Oil on spark plugs ???.

I have a 1998 Toyota Corrolla with 210,000 miles I bought it from the original owner six months ago. The engine recently started jerking when shifting between the third and fourth gears mostly and other times just not with the same frequency. Today I replaced the spark plugs and wires based on dvice from this forum. Haven’t seemed to have a problem yet. Here in lies the problem though I have a receipt from the first owner where she had the valve cover gasket replaced in Sept 2010 is it normal for those things to go bad in year? If not does that mean I have a BIG problem, as in piston rings? As far as I know the spark plugs were not changed at the same time as the gasket. Do you think one is related to the other?

It could have been installed incorrectly, or it may just need a bit of tightening. Lasting a year doesn’t really mean very much. Try tightening the valve cover nuts, but don’t over-tighten them. What’s too tight? Hard to describe. Give it a shot, anyway.

It’s funny you mention the tightening bit. My Dad went with me when I bought the car and noticed a loose bolt on the valve gasket cover we tightened it and I haven’t thought about it since. I will definitly check it. As far as tightening I’m female so my tight may be be just right haha I find that it usually is just right not too tight but not over tightened. Thank you for responding.

It all depends on the engine design whether the valve cover has ANYTHING to do with oil on the plugs…If the spark plugs are located down inside tubes in the head or valve cover, then yes, oil can leak into and slowly fill these tubes with engine oil, shorting out the plug and causing a mis-fire…When these flooded plugs are removed, the oil can run down the plug and make it appear the that the tip of the plug is covered in oil that resulted from an internal engine problem…But that is seldom the case. Usually, it’s the same oil drooling from outside the engine to inside the engine…Hopefully, replacing the gaskets and seals, plugs and plug wires will cure the problem…

Yes Caddyman my plugs are located in tubes on top of the valve cover. I will replace the gaskets and seals. Should I replace the wires and plugs since I aready have.

By the way I am a little confused did you mean “But that is seldom the case” that the oil rarely runs down the plug upon taking them out or that the tip is covered in oil from the oil being in the internal part of the engine.

Yes, change the plugs and wires, the oil ruined them…

The USUAL situation is for the oil to have run down the plugs to the tip as you removed them…NOT from inside the combustion chamber. If that were the case, your exhaust would be spewing blue smoke and you would be burning a LOT of oil…

If you just changed the plugs and wires there shouldn’t be any reason to change them again if the car is running OK, but if you have a miss in the engine it’s possible the oil damaged one of the new plugs or wires. Be careful tightening the valve cover bolts. Valve cover bolts are usually very low torque and if you over tighten them you run the risk of stripping the threads out of the hole or warping the valve cover.