Blown spark plug and heli-coils

[calrockx]

So I was driving around town the other day and all of a sudden...LOUD NOISES! Haha, turns out it was a blown spark plug.

Anyway, took it to a shop they diagnosed it as a popped spark plug in cylinder #3. Pulled it out and out came the coil, stripped threads.

They fixed it using a heli-coil and replaced the spark plugs. But said this could be considered a temporary fix. Not that it'd blow again anytime soon, but something to consider next time I'm changing the spark plugs.

So just how "temporary" should I consider the heli-coil fix?
I guess the real way to fix it is to re-thread the cylinder head, which seems like a pricey affair.

[mastacox]

I would consider it permanent, although it may not seal as well as it used to... Your only other option other than a heli-coil would be a permanent threaded insert like a keensert, but I'm not sure there is enough room for something like that to fit...

You can't re-thread the cylinder head without first adding material back where it stripped out, which would mean a welded-in plug that is tapped with the proper spark plug threads. I'm not sure I've heard of anybody doing this though; as far as I know it's heli-coils or a new head.

[Seanz0rz]

id keep my eye open for a new (used) head

[corax]

I've seen heli-coiled plugs last forever in the past if it's done right - best would've been a solid threaded piece like "time-sert" or similar though

[CJM]

Time sert woulda been best, but a helicoil should be fine if they did it ok. If I were you I wouldnt touch that plug ever again just to play it safe.

[slosurfer]

You aren't running Bosch plugs are you?

[Robinhood4x4]

Huh, never heard of a timesert. Learn something new everyday.

We use keenserts at work all the time. I don't think sealing would be a problem since keenserts are inserted below flush with the surface so the seal of the sparkplug will seal like normal as long as you use one of the smaller ones.

[calrockx]

You aren't running Bosch plugs are you?


nah, i think they're denso.

well okay, good responses here. i'll just leave it alone, not go rushing out for another fix. it's been driving fine since i got it back, so far their install seems just fine.