[NKau]

Was changing the spark plugs in my 5.0 today, and noticed that the plugs were torqued in pretty tight. After pulling them all and replacing most of them, I began screwing in the one that is the second back from the front of the motor on the passenger side of the motor. It seemed like it was beginning to tighten......then complete looseness while turning :0 After some more turns it just suddenly stopped in the head and got tight. I started the car up, and it seems to run fine, but using the edge of the valve cover as a plane and looking down across it, I can see that the one spark plug is noticeably farther into the head than the others. If you feel around the base of the plug, the hexagonal portion that you crank on is a lot closer to the surface of the head than any of the other plugs on that side of the motor.
Am I just paranoid, or could something be up here? I plan on just running the thing and forgetting about it as the thing seems to run alright, but I really don't want to pull that plug out again. Anyone have anything like this happen?

 

[mlnielsen]

You're right, sounds like you stripped out your threads. Many auto parts stores sell HeliCoil type spark plug thread repair kits. Make sure you get the right thread size kit. They run about $35, but come with a tap, installation tool, and several inserts. I think they're solid inserts, and should last quite a while.

When I install new spark plugs, I always use some anti-sieze on the threads. This prevents galling of the threads and makes removal easier. Don't use too much, it can damage O2 sensors. I also use some silicone grease on the other end where the wire goes. This prevents the wire boot from melting to the ceramic on the plug.

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The silicone grease is sold as "silicone dielectric grease".

 

[nosaj122081]

Another hint I learned from working on Talons/Eclipses (DOHC, so the spark plugs sit down in wells in the heads, maybe 4 inches) was to stick a piece of vacuum line on the ceramic side of the plug and use that to start it in the hole, that way you still have control over it but can't put enough torque on it to strip out the thread.

 

[spinner]

You want to make sure that the plug is properly threaded and torqued. Conceivably, the plug can pop out of the head when driving if the threads are stripped.