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Is there anything I can use short of Helicoil, which I'm really hoping not to have to use, to make sure a bolt sits in its threaded socket in my engine block and torques to spec ? The problem that I am having on my Tacoma is that there is a timing chain cover bolt which reaches the end of the hole but the hole threads (I made sure it is not the bolt by putting the bolt in another hole and trying to put another bolt in that hole) won't grip it tight.

Will something like thread locker be helpful ?

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  • Just to be clear, is it just spinning in place no matter how much you tighten?
    – Zaid
    Sep 10 '15 at 17:47
  • yes, exactly, spinning in place no matter how much i tighten.
    – amphibient
    Sep 10 '15 at 17:48
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    Ok, you've stripped the thread in the bolt hole. Thread locker won't help unfortunately. I'll post up an answer in a bit, but in short helicoil is the standard solution. There are other alternatives but no shortcuts
    – Zaid
    Sep 10 '15 at 17:51
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Loctite thread repair product #: 28654 (also known as Form-A-Thread) may help your problem. I wouldn't suggest using it on a headbolt but I think on a timing cover it would work. Basically it a filler material and a release agent. You fill the hole with one of the materials of the kit. The bolt is coated with a second material, a release agent that keeps the bolt from sticking to the filler. The bolt is inserted in to the filled hole. The bolt forms the threads. Once the filler material hardens the bolt is removed leaving the threads in place.

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  • Since these are only to be torqued to 17 lb-ft, this isn't a bad choice. I'm not sure why people are afraid of Heli-coils though. They are relatively easy to use (even for a novice) and work rather spectacularly. I guess amphibient has his reasons. Sep 10 '15 at 21:47
  • @Paulster2 -- the reason in this case is that it is not a regular bolt but one of those studs that look like a headless bolt that has threads on both sides and on the outside also has an inverse torx driving head on which a nut goes. the nut is barely wider than the hole so if i drilled a Helicoil hole, the nut would not have any holding surface unless i resorted to a washer. so i would have to take the timing chain cover off and I don't want that because i applied the gasket maker already and torqued the rest of the bolts. i am thinking of injecting some JB weld or titanium epoxy (cont.)
    – amphibient
    Sep 11 '15 at 15:49
  • in the hole and then setting the stud in and let it cure ... also hoping that i never have to take it out again
    – amphibient
    Sep 11 '15 at 15:49
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Unfortunately, thread locker won't help here

That's because the thread is damaged, and thread locker needs thread to help secure the bolt in place.

No thread → no grip → bolt will still spin in place.


Helicoil is the standard go-to solution to solve this mess

There are other alternatives, but no shortcuts:

  • metal putty, which should allow you to fill the hole and recreate new thread
  • Keen-serts, if the Helicoil repair didn't work out as planned

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