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Thread: Head Bolts - Torque to Yield or Reusable?

  1. #1
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    Head Bolts - Torque to Yield or Reusable?

    mechanic buddy raised a horrible question .. are 4AGE headbolts reusable or are they torque to yield?

    going to do HG this w/end and really don't want to spend more money on this..

    thnx

    Brett

  2. #2
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    I thought they were stretch bolts? I would replace em.
    I am your 4ajesus

  3. #3
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    ive always re used them. i know Nick probably reused those ones when he did the head too

  4. #4
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    I've always reused them as well. 6+ engines so far, and I know that Toyota dealerships reuse them

    Migs

    1986 GT-S Hatchback, 2002 IS300 5MT w/LSD, 1991 22RE 4x4 Pickup

  5. #5
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    I would replace them as well. It's always a good thing to replace bolts anywhere on your car with newer ones rather than reusing them, especially if they're like 10 years old.
    - TVK -

    "There's A Vid In All Of Us!"
    "Do You Know How I Fix Rusty Cars? I Buy A New One." - Ben (Soulibrium)

  6. #6
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    oops..........

  7. #7
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    I know lots of people who reuse head bolts, and can't name one who has had a problem with them -- myself included.

  8. #8
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    A torque-to-yield type bolt will have a torque spec like this:
    23 lbs.ft
    44 lbs.ft
    90 deg turn
    90 deg turn

    A regular bolt will have a torque spec like this
    Torque: 600kg.cm (43 ft.lbs, 59 N.m)
    The newer Toyota engines use torque-to-yield bolts, the older ones do not. Torque-to-yield bolts also have a spec for length, once the length is exceeded, you cannot re-use.

    Bottom line: it's okay to re-use 4A-G head bolts, crank bolts, rod bolts, etc.
    - Brian


  9. #9
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    on my smallports valve covers it reads:

    cylinder head bolts
    22 fl/lb
    +90 deg turn
    +90 deg Turn

    does that mean i cant re-use the head bolts?

  10. #10
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    Toyota has always recommended to me to replace them every time, and the head mechanic at the nearest dealer claimed they were "stretch" bolts. Cheap insurance...they're not nearly as pricey as you might think.

    15psi + 200hp + 2400lbs = GOOD!

  11. #11
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    Quote Originally Posted by twotone_ae86
    on my smallports valve covers it reads:

    cylinder head bolts
    22 fl/lb
    +90 deg turn
    +90 deg Turn

    does that mean i cant re-use the head bolts?
    Uh, I guess the EARLY 4A-G bolts are reusable. If the late ones are stretch bolts, then you need to measure their length. The manual will say what that spec is. I didn't know the later ones had stretch bolts. The current Toyotas all use stretch bolts.
    - Brian


  12. #12
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    at a whopping 6.60$ each before the decade discount I got Metro to bring in a full set .. will be here tomorrow from over there in Van..

    if nothing else I can keep the old ones for spares if they all check out ok..

    thanks for the input all..

    Brett

  13. #13
    Pentavalver Guest
    Never ever reuse rod bolts on any engine.

  14. #14
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    now, this is something i don't know for sure, but anyone with a parts number catalogue could look up numbers from different years and see if they changed.

    when i used to work at hyundai, they sent around a TSB, giving us different headbolt torques. same bolts, but they wanted us to use a more accurate method.

    the old spec was say 55 ft/lbs, but they wanted us to start torquing them to say 22 ft/lbs + 90 + 90. the end result was the same, except that each bolt was supposidly more accurately torqued, putting the same stress on the cylender head as the other were.


    now, is this what toyota did 20 years earlier? i don't know, but they may have.

    i always buy new ones. like mac said, cheap insurance. on other applications, other manufactureres want you to measure the headbolts agianst a brand new spec, and if any are out you are supposed to replace them. i guess if nothing else, compare them to each other first.
    1985 Corolla GTS
    1988 MR2

  15. #15
    Pentavalver Guest
    "now, is this what toyota did 20 years earlier? i don't know, but they may have".
    Yes.

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