Threads stripped, heli-coils failed...

[BassGuy]

1987 760Ti

I replaced the exhaust manifold and turbo, and as I was torquing down the stud, no.1 cylinder top slipped, then kept spinning.

I went out and bought a heli-coil kit and tapped out the hole with the over-sized tap.

I then threaded on coil in, backed out the stud, threaded a 2nd coil in, backed out the stud, but then the 3rd coil, as I was tightening, backed up onto the other 2 coils. I'm not sure what to do now.

My thought was to drill out the hole, tap it, and have a threaded "sleeve" machined for it. What does the mighty TB advise?

[as an aside, I had a partial brain fart; when I threaded the stud in, I forgot the fat washer, so I now have a stud with a lock nut and 3 nice and tight heli-coils stuck on.)

 

[745 TurboGreasel]

snap off the drive tang and thread the stud in?

 

[MasterBlaster]

I then threaded on coil in, backed out the stud, threaded a 2nd coil in, backed out the stud, but then the 3rd coil, as I was tightening, backed up onto the other 2 coils. I'm not sure what to do now.

Sorry, I don't understand what you did. 3 coils of different sizes inside each other, or 3 coils end-to-end to fill a really deep hole?

 

[meeki007]

I have never gone back http://www.timesert.com/

kinda spendy but worth it.

you can order longer or shorter inserts besides the supplied 11.7mm length.
http://www.amazon.com/TIME-SERT-Metric-Thread-Repair-1812/dp/B001JK44LG

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I bought one of these kits after the mechiene shop said it would be 60 USD to do a proper re-thread insert and 2 helicoils failed. I had to get a 10mm kit after an egr valve striped out when removing stud on my ford.

If what happened to your head happened to me id just pay the 60ish usd to get a timesert kit in 8mm 1.25 kit.

other people have also just tapped in 10mm threads and then drilled out the hold on the manifold to accept new size but after bits and tools, bolts and nuts, its going to cost the same as the kit.

 

[epjetta]

x2 on the timeserts. i have used them for years with never a problem. probably stronger that the original hole for exhaust studs.

 

[Coupe' de Grace]

and they also make big-sert for those beyond 'normal' dimensions