Questions and Answers
Stripped Spark Plugs
Q. Dear Mr. Ciulla, I have a 1993 Subaru Legacy 2.2 liter, with a 192,000 miles. I recently had a major tune up on my car. My mechanic repaired a stripped plug and a cross threaded plug. I noticed that on the stripped plug, the spark plug wire is not seated like the others. I have tried pushing it down, but it does not seat. My mechanic states that it will be like this until I replace the head gasket (apparently my plug was badly stripped).
Since the tune up, I noticed that after driving over 20 or so miles, my engine is very hot (hotter than normal). My temperature gauge registers that it's NOT overheating. I do not see any smoke coming from the engine. But, after turning off the engine, it's very hot, a burning smell is coming from the engine and there is a faint ticking noise present. It sounds like it's coming from the same side of the engine as the stripped plug. After about one and a half hours later, the engine is still very hot, but the smell and noise is not as strong.
Is it true about replacing the head so the plug wires will seat properly? And is this burning smell, noise and temperature of the engine cause by the stripped plug or do I have other problems?
Thanks for your help...This is a great site.
KimA. If I can call you Kim, you can call me Vince. Okay?
If the thread repair was done properly, the spark plug wire should sit on the spark plug normally. Replacing the head gasket will not affect the spark plug wire at all. Perhaps he meant replacing the whole cylinder head?
I suspect that it was so badly damaged that he couldn't get the plug to sit properly in the head and it's either not all the way in, or it is in the head at an angle. It doesn't take a whole lot to mess up the spark plug threads on an aluminum head since aluminum is much softer than cast iron. I have a spark plug thread chaser to clean the threads on an aluminum head, but for an actual thread repair, I send the head to a machine shop to have a heli-coil put in. They are much better equipped to do a repair like this then I am.
As for the engine seeming hotter than normal, I'd have to see that. After a 20 mile drive the engine would be hot, and the ticking noise you hear is probably just the heat shields cooling down. A normal noise that they make. It may be that you are just noticing something that is normal for the car with while looking at the spark plug problem.
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