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Heli coil failed

Posted by Ces4rDSM, Aug 21, 2019

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  1. Ces4rDSM

    Ces4rDSM Proven Member

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    watsonville, California
    I had to instal 2 heli coils for my exhaust manifold studs due to the fact that the threads broke on the 2 holes, my first heli coil did fine that is until I took my exhaust mani off and reinstalled but both heli coils ended up losing tension when I torqued the bolts. Now it looks like every time I torque, the studs appear to come out of the hole again. Same problem. Now how should I repair ?
     

    Street Build 148  1

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
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  2. mitsubishikid

    mitsubishikid Proven Member

    821
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    Turlock, California
    send it to a machine shop and have them weld shut and then have it re-drilled and tapped to
    metric 8x1.25 it will not be cheep but it can be done. depending on how much you have invested in the cylinder head, you might consider finding another head, especially if it's a mostly stock head.
     

    985  0

    1990 Eagle Talon TSi AWD
    manual · 1G DSM
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  3. silvreclips

    silvreclips Proven Member

    1,003
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    Greenville, South Carolina
    You can try a different type of insert if you have enough material around the hole. Keenserts have a larger OD so you can drill it and retap that hole again.
     

    Autocross Build 181  1

    1998 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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  4. Vegas smith

    Vegas smith Proven Member

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    Houston, Texas
    Worst case scenario is you can drill to a larger size such as 10x1.25. You would of course have to drill out the exhaust manifold holes for 10mm as well but that's not hard.
     

    Street Build 3K  10

    1993 Eagle Talon TSi AWD
    awd · manual · 1G DSM
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  5. tk106

    tk106 Supporting Member

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    Cincinnati, Ohio
    Vegas’s method would be the cheapest way to go
     

    143  3

    2000 Jeep Cherokee Sport - Classic
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    147  4

    93 Civic 4 Door -sold-
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    1992 Eagle Talon TSi AWD
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  6. Ces4rDSM

    Ces4rDSM Proven Member

    106
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    Joined Feb 2, 2019
    watsonville, California
    Damn, I'm getting to the point where I might sell the car and keep the engine. I dont have the space to always work on it and it just takes so much patience.
     

    Street Build 148  1

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
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  7. tk106

    tk106 Supporting Member

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    Cincinnati, Ohio
    Can’t count how many helicoils I’ve installed over the years. Prob over 10 on just my current dsm and never had an issue with it coming loose. Is it possible you used too big of a drill bit? Think I’ve installed 4 for the exhaust manifold and a lot for the valve cover.

    I get your frustration and hope you get this sorted.
     

    143  3

    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

    147  4

    93 Civic 4 Door -sold-
    fwd · manual · Misc Vehicles

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    1992 Eagle Talon TSi AWD
    12.625 @ 111.42 · 1G DSM
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    silvreclips likes this.
  8. Ces4rDSM

    Ces4rDSM Proven Member

    106
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    watsonville, California
    To be honest with the amount of space I was working with, and the time on my hands the heli coils were done decent. My guess is the threads holding the heli coils broke. Or maybe I torqued the bolts too hard. I was torquing the bolts to 28 lb of pressure
     

    Street Build 148  1

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
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  9. tk106

    tk106 Supporting Member

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    Cincinnati, Ohio
    Think it’s 18-22.
     

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    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

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    93 Civic 4 Door -sold-
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    1992 Eagle Talon TSi AWD
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  10. Ces4rDSM

    Ces4rDSM Proven Member

    106
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    Joined Feb 2, 2019
    watsonville, California
    That's probably why. 22 lbs felt too little for me so I usually torque them to 25 lbs but this time i went 28 lbs
     

    Street Build 148  1

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
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  11. tk106

    tk106 Supporting Member

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    Cincinnati, Ohio
    The a
    Probably. The aluminum used to cast these heads weren’t the best.
     

    143  3

    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

    147  4

    93 Civic 4 Door -sold-
    fwd · manual · Misc Vehicles

    Street Build 2K  6

    1992 Eagle Talon TSi AWD
    12.625 @ 111.42 · 1G DSM
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  12. Ces4rDSM

    Ces4rDSM Proven Member

    106
    5
    Joined Feb 2, 2019
    watsonville, California
    Yea but my torque wrench has a min torque value of 25
     

    Street Build 148  1

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
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  13. Ces4rDSM

    Ces4rDSM Proven Member

    106
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    Joined Feb 2, 2019
    watsonville, California
    Yea what's your recommendation? Sell the shell and keep the motor for future swap ?
     

    Street Build 148  1

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
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  14. tk106

    tk106 Supporting Member

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    Cincinnati, Ohio
    I use harbor freights. It’s only $15ish
     

    143  3

    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

    147  4

    93 Civic 4 Door -sold-
    fwd · manual · Misc Vehicles

    Street Build 2K  6

    1992 Eagle Talon TSi AWD
    12.625 @ 111.42 · 1G DSM
    Loading...
  15. tk106

    tk106 Supporting Member

    1,574
    393
    Joined Sep 11, 2017
    Cincinnati, Ohio
    Idk...
     

    143  3

    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

    147  4

    93 Civic 4 Door -sold-
    fwd · manual · Misc Vehicles

    Street Build 2K  6

    1992 Eagle Talon TSi AWD
    12.625 @ 111.42 · 1G DSM
    Loading...
  16. Ces4rDSM

    Ces4rDSM Proven Member

    106
    5
    Joined Feb 2, 2019
    watsonville, California
    Mitsubishikid I hadn't seen your post! I think ima end up doing so. Does anybody know how much it adds up to in cost by retapping the holes after welding them ?
     

    Street Build 148  1

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
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