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Trans problem

Discussion in '1992-Present Chevy & GMC models' started by wasted wages, Jun 3, 2004.

  1. wasted wages

    wasted wages 3/4 ton status

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    Here's one for all you trans guy's ,,,

    My 97 GMC Yukon has this problem that starts only when the trans is hot and has been running down the road for a while.
    I think it's a 460LE???

    When the trans is cool and driving arround town and in traffic it shifts normally, /forums/images/graemlins/thumb.gif,,,but when it's been driven at highway speeds,,,and then you stop and then go again the trans will shift HARD like it has a shifts kit in it (even harder)(It really bangs hard into second) /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif (It acts like the clutch packs are getting slammed with high pressure fluid) /forums/images/graemlins/yikes.gif
    and will continue to shift like that untill the truck is shut off and the truck sits about 10 minutes and then it shifts fine again,,,,, the "service engine soon" light comes on when this happens, does the trans throw a code that can be read?

    It does not slip,fluid has been chenged twice in 84K miles.
    The trans works perfectly other than this hard shift problem,,,what gives?????? /forums/images/graemlins/dunno.gif /forums/images/graemlins/dunno.gif /forums/images/graemlins/dunno.gif
     
  2. Burbinator

    Burbinator 1/2 ton status

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    Had the SAME exact problem with my '98 Tahoe...

    The MIL will set eventually, if it hasn't already. Read your computer and look for the code that indicates "trans component slipping"...I can't remember the exact P code off the top of my head.

    Basically, the input and output RPM's are compared by the ECM. If the RPM differs by more than 400 for three or more run cycles, it will increase trans line pressure causing the hard 1-2 shift and the computer will set a code and light the MIL. If your MIL isn't lit, the code will be pending, more than likely.

    The fix for this is a new, revised aluminum valve body that has a steel insert in the piston bore. The old style is plain aluminum (no insert) and leaks over time.

    This is an EXTREMELY common problem on the 4L60E...don't get conned into replacing the trans!

    Revised valve body from the dealer is about $400. I replaced the one in my Tahoe and it fixed it permanently. The test was 115+ temps in Phoenix during the daily commute!

    Good luck!
     
  3. bckinblk

    bckinblk 1/2 ton status

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    I am starting to have this problem also in my 97 tahoe. How bad was it to change out the valvebody? How did you do it.Do I have to pull my tranny out?? Thanks for any help..
     
  4. wasted wages

    wasted wages 3/4 ton status

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    bckinblk,
    I sent you a PM
     
  5. wasted wages

    wasted wages 3/4 ton status

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    burbinator,,many thanks dude,,the valve body did the trick!!
     
  6. bckinblk

    bckinblk 1/2 ton status

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    Thanks man I will fix mine soon.. /forums/images/graemlins/thumb.gif
     
  7. Burbinator

    Burbinator 1/2 ton status

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    Sweet...glad to help!
     

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