Helicoil?

[GeoffBooth]

Everyone and everything leads be to believe my head gaskets blown. This now brings me to another problem that I have been waiting for a reason to take the head off. My #4 plug is probably cross threaded, half way in. Been like this for years. Thought I'd leave well alone. Someone on here must have used Helicoils. Are they any good? Do I need a new head? I do a lot of drilling and taping at work, can this be drilled out and some kinda reducer fitted or maybe even chase the thread out from the face seeing that the plug is only half way in.

Geoff

[MR2Jedi]

They're OK. A Helicoil kit usually comes with a tap for a new thread specifically for the thread coil. Tirmeserts are better.

[Ghostyman]

Helicoils are good, they're actually stronger than the original threads (especially in aluminum like this). I'd apply some red Loctite to the outer part of it when putting it in to make sure there's no way it can thread into the combustion chamber later. Timeserts will work just as well.