Thread: Sooty spark plug, only one

Originally Posted by Reptile

I've seen many times where the threads get pulled in heads. It's not really that common in cast iron as opposed to aluminum where it happens 90% of the time.

That's why using a type of anti-sieze will help lubricate the threads to keep the plug from grinding away at the cast iron.

Interesting thought. And I was so careful making sure the area was free of debris, and only snugging the plugs. Out of all of the cars I've owned and changed plugs on, I've never seen this happen. Even the motorcycles with the aluminum heads.