Thermostat housing helicoil help

Discussion in 'Engine Topic' started by 7.62fmj, Dec 18, 2017.

  1. 7.62fmj

    7.62fmj Veteran Member

    104
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    May 16, 2017
    Jacksonville, Fl
    Not sure if this is the right section.
    Over the weekend I flushed my cooling system and replaced my thermostat.

    It was an easy job until I realized that the reason the prior gasket had been leaking was because the bolt hole was stripped.

    So I drilled, tapped, and put a helicoil in the hole. Well it turns out that I didn't drill deep enough and the bolt stripped when I tried to torque it down.

    How do I fix this? Should I drill and tap for a bigger bolt? Can I just use a 3/4" long bolt?
     
  2. djorgensen3

    djorgensen3 Veteran Member

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    Oct 15, 2009
    Peoria, Az
    Cardinal likes this.
  3. 7.62fmj

    7.62fmj Veteran Member

    104
    3
    May 16, 2017
    Jacksonville, Fl
    Would I have to retap to use that or can I use it in place of the helicoil
     
  4. djorgensen3

    djorgensen3 Veteran Member

    338
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    Oct 15, 2009
    Peoria, Az
    Drill and tap for insert. It's all in each kit...a drill bit, countersink tool, tap for insert, and installation tool.
     
  5. 7.62fmj

    7.62fmj Veteran Member

    104
    3
    May 16, 2017
    Jacksonville, Fl
    The kit for a 3/8 bolt has a drill bit .397 in diameter, the 3/8 helicoil used a 25/64 (.391). Since the timesert uses a slightly larger bit, can I use the 3/8 kit or would I need to size up to fully drill out the helicoil tap thread?
     
  6. djorgensen3

    djorgensen3 Veteran Member

    338
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    Oct 15, 2009
    Peoria, Az
    I don't have the answer for that...sorry.
     
  7. COPO

    COPO Veteran Member Lifetime Gold Member

    16,249
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    Sep 15, 1999
    Ontario, Canada
    I would buy the correct bit for the insert. Bits are not that expensive. I remember repairing the same thing back in 1975 on my 71 Z28.
     
  8. 7.62fmj

    7.62fmj Veteran Member

    104
    3
    May 16, 2017
    Jacksonville, Fl
    What I meant was that would the 3/8 time sert kit bore out enough that I could tap for the insert or would I have crossing threads from the helicoil still present. I may have to size up to a larger bolt and drill the housing, I haven't been able to find a spec for the helicoil od
     
  9. djorgensen3

    djorgensen3 Veteran Member

    338
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    Oct 15, 2009
    Peoria, Az
    It might be better to upsize to the next larger insert so it can have enough material to bite into. The inserts flare out at the bottom from the installation tool. They also get loctited in.
     
  10. 7.62fmj

    7.62fmj Veteran Member

    104
    3
    May 16, 2017
    Jacksonville, Fl
    So it seems like that's the way to go. Still a couple lingering questions (this forum is so helpful). Is it worth doing the insert vs just drilling and tapping? And is there a cheaper place to buy that kit? My local mechanic only charges $50/hr and he already has all the tools so not much parts cost. It's almost $100 from Amazon!
     

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