Got a stripped spark plug thread, so rather than have someone insisting I need a whole new cylinder head (which no doubt a main dealer would do), has anyone had the experience of re threading the damaged area and fitting a helicoil (or better still, a specific insert)?
I've had it done on a Honda Fireblade engine. A few years ago and still fine. I don't think I'd do it myself.
Yes. You need a timesert really as the helicoil removes the bit that 'hugs' the end of the plug. If you look at the fire face of a head you will see what I mean. I had a blade head in for doing but after I quoted including getting the timesert set the owner found a second hand head and we fitted that instead.
What is it.
Alfa 145. New cylinder head on an old car is a non starter. Finding a secondhand one won't be easy I imagine.
There's some on ebay
I helicoiled a Talbot Horizon spark plug thread about 20 years ago. Never had a problem with it afterwards. Had plenty of other issues with the car mind 🙂
Had a motobike engine helicoiled professionally once, as above, it's not something I'd want to do myself. Had to get it done twice though, as the first one unscrewed itself when the engine was hot!
Yes, had one cylinder done professionally, no problems
loads of times, usually sump plug threads etc... Work well.
there's also something called Timesert which is argued to be better
Yes. I had a tame mechanic helicoil a plug with the Cylinder head still on on a Rover 414. It worked fine and the car ran for years after. Obviously doing it in situ there's a risk of a bit of sharp metal dropping into the Cylinder and doing damage. Tame mechanic was uneasy about doing it but I assured if I wouldn't blame him if it went wrong.
My Grandad worked for Ford making tractor engines in the 50/60/70s and he said they used to regularly leave the factory with a helicoiled plug or two.
thought the same on my sons freelander, turned out the plug had vibrated loose first and only stripped the last few threads.