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Should you re-tightening head gasket bolts after 150k-200k mile?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Anklepain, Oct 2, 2024.

  1. Anklepain

    Anklepain New Member

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    I found this post and pictures from toyota prius facebook group. Im thinking to re-tightening my head gasket bolts with torque wrench.

    There could be possibility that bolts are stretched after 150k-200k miles. This would maybe enable coolant and oil get into in bedween head gasket, therefore it would corrode the head gasket.

    I know majority people believe that the reason for head gasket failure is from neglecting to clean the egr, intake and replacing water pump. I just want to add something new for discussing.
     

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  2. Anklepain

    Anklepain New Member

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    Ps. You should open the picture to see if this post makes any sense. The bolts in picture is stretched about 1-2mm. Even 0,5mm is too much, in my opinion.
     
  3. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    I wouldn't touch it. For starters it's not trivial to dig down far enough to access the head bolts. Never done a head gasket (knock on wood), but just off the top of my head, think you'd first have to first remove:

    coolant
    water pump
    oil filter bracket
    engine mount
    valve cover
    "balancer" pulley
    timing chain cover
    timing chain and guides
    timing chain tensioner
    cam shafts
    cam shaft cradle
    rockers and associated

    Then carefully scrape clean mating surfaces, apply various form-in-place gaskets, replace gaskets, reinstall the above, refill coolant.

    To check something that's almost certainly as it should be?

    If you were going through all that, I'd go the extra step, replace the head gasket, lol.

    The poster you link had a head gasket replacement fail soon thereafter, likely because he screwed something up in the process, or didn't touch the EGR.
     
    #3 Mendel Leisk, Oct 2, 2024
    Last edited: Oct 2, 2024
  4. ASRDogman

    ASRDogman Senior Member

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    The drain plug bolt is NOT a stretch bolt. It is not, and won't stretch, unless over tightened.

    To "retorque" the head bolts, you'll have to loosen them all, in sequence, the tighten again,
    in sequence. Which will allow cools to leak into the cylinders and oil. Thus ruining the head gasket.

    The head bolts are stretch bolts. After initial torque, there are 2, 90 degree turns. Which
    stretches the stretch bolt. There is certainly enough torque to secure it and keep it secure
    to the block.

     
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  5. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    It's a 90 degree, then 45 degree turn.

    Yeah bottom line, it's NOT sensible to do this, just on a whim.

    Full disclosure: I've never done a head gasket, but have an inkling of what's involved.
     
  6. Mr.Vanvandenburg

    Mr.Vanvandenburg Senior Member

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  7. Kenny94945

    Kenny94945 Active Member

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    My initial vote - No

    If it was 200 miles (from a head gasket repair/ removal) and not 200,000 miles - perhaps.
    I have not removed the items necessary to reach the bolts, yet it seems this is a big job.
    But, if you like to "tinker" on cars, no harm no foul accessing the bolts, other than new gaskets (here and there) and some spark plugs (since you are "in there" ).

    Good luck with your decision and OP, PS let us know if you do this and what you found with the bolts.