Stripped the threads in one of the "M8" cylinder head bolt holes today. Read through a number of threads on the time sert kits, just want to make sure that I need the -100 and -300 kits off ebay (every thread I read seemed to be about the "M11" bolt holes). If the kits are complete that should be everything I need to repair this? Also want to make sure that helicoils are a no go for head bolts.

 

Ok, so it looks like this will only take care of the M11 bolt holes. I've found the kit(s) that I need, but still have a couple questions so here goes.

The bolts are 45mm, but the inserts don't seem to come in any size larger than 20mm- will that be enough thread?

How difficult is it to drill this hole out for the insert?

Do I need to completely remove the head prior to doing this or can it be done with the head still on? Any major risks to doing it with the head still on? I realize you can't use the plate guide with the head still in place, any suggestions for a guide to use with the head in place (if thats even feasible)?

 

A heli-coil isn't good enough for the bigger head bolts. The smaller top row of bolts only get 22 ft pounds. I dont see why you couldn't do a heli-coil for them, or even re-tap them the same size if you stripped one and see if it has enough threads left to hold.

 

Not sure if there are many threads left, I had at least half the threads on the bolt when I got it out.

Any chance of being able to put in a helicoil w/o pulling the head off or too risky?

 

I have never done a heli-coil. I do understand how they work though. I don't see why you couldn't do one with the head on.

 

I think it will come down to fitting the drill + bit where I need to.....while still being able to drill the hole straight. I'll have to go measure.

 

Yep, may be a judgement call on this particular situation.

 

A Helicoil will hold a lot more than you think, We use them a lot at work on large equipment, Ive seen a 3/4" grade 8 bolt broke flush and it had a helicoil insert, And helicoil did not move and reused the coil after removing the broke bolt. All my rocker arm bolt holes a coiled. You can get the M8 helicoils at any parts store, like Advance or Autozone.

 

Same thing happened on my car however I didn't do the work nor has the car been driven alot since the heads and cam install but he had to drill the block out and re thread it using a bigger bolt but I don't know which head bolt this happened to but I would only do that as a last resort. And I would think it would be better to leave the head on the block. Seems as if it would be easier to get the drill straight. good luck

 

Yea, I'm gonna pick the helicoils up this week and give them a try. Hopefully I can get this done over the weekend and finish painting and put her back together.

 

Is this a common problem on the motors

 

Its not the engines, it just aluminum, Every time you tighten and loosen and re tighten, The threads stretched and give way, and the threads just separate from the threaded bore.

 

Hate to hijack his thread but roughly how many heads swaps will the block take. My ls6 just had heads taken off at gm last summer and I'm thinks about sending them to ai