Plug Inserts

[Dame]

Hi guys. As you may already know, I have got an MR2 with a stripped plug thread. The idea is to hopefully vut a larger thread and use an insert. Has anyone done this before to a 3SGE? The plugs are recessed deeply into the head, making it much harder than on a standard engine.

[Kelvyn]

Surely the head has to come off to fit the insert?? I would have thought that the hole would need to be drilled bigger to allow for the thickness of the insert. You wouldn't want metal swarf getting into the bore and there would be no way you could stop that without taking the head off would there?? Assuming you did take the head off then the plug hole would be close to the surface so fitting the insert would then be easy. A few years ago I had a Vectra that needed an insert fitting. Took the car to a local Vauxhall dealer for a major service(including cambelt) and 2 days after I got it back one of the plugs blew out of its hole knackering the thread in the process. Had the car taken back and they denied any fault but out of the goodness of their hearts they fixed it for free. Well vectra plugs are recessed too. Dont know exactly how they did it but they said they had to fit a HELICOIL insert.

[Dame]

Thanks for the reply. we're still looking into this. The head would indeed have to come off, it's mainly because of the access needed to drill out a larger thread. You can do it in the car, and use grease to catch the bits of metal, but TBH I wouldn't want to risk this!! The biggest issue is whether there is enough metal between the valves and the plug hole. Considering valves are mushroom shape, there should be plenty of space there. It's really a case of getting the head off and having a good look.... Looks promising though :)

[Kelvyn]

If the thread isn't totally knackered maybe it would simply clean up. Once you have the head off you could run a normal size tap up from the combustion chamber end to try to clean it up, that way if you're lucky you wont need to insert it.

[Dame]

Haven't had the head off yet, but the plug doesn't tighten up at all. I'm a bit reluctant to simply clean it up, I wouldn't like to trust it, though something definately worth exploring.... Just need some nicer weather......

[Matt wantsatoyota]

a simlar thing happend to my brothers car, we had to get a helicoil kit and remove the head, unless ur good at removing swarf from deep inside engines its certainly not worth taking a shortcut :D

those helicoil kits you can buy seem a bit pricey but they do the job well

[Dame]

Cheers for that. May be a bit pricey, but cheap compared to the cost of a new head!