I changed the plugs today. Two of the four 10 mm bolts that hold the plug connectors in place made a popping sound like they had snapped off. Took them out, they’re fine. Now neither will tighten. I didn’t over tighten them but I’m guessing after 13 years the threads in the valve cover gave way. Is that a correct assumption? If so, can the holes be re-threaded or do I need a new valve cover?
Go to Sears or an ACE hardware store and get this thread restoring kit.
This kit has saved my butt several times when threads got damaged from doing what seemed like a simple job.
I would buy a new valve cover instead of trying to restore the threads.The valve cover has to come off anyway and a new gasket put in.
The bolts referred to are to hold the coils in place and are blind into the valve cover. Cleaning up the threads with the kit as @Tester posted, doesn’t require the valve cover be removed unless there is no clearance to reach the threads. A thread insert, like a heli-coil would work if the threads are too buggered to clean up.
Edit: OK, replace valve cover, THAT requires new gasket. I was confused by your comment.
Heli coils will do the trick.