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TH350 Problem

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Marc72, Jun 7, 2001.

  1. Marc72

    Marc72 Registered Member

    Joined:
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    Location:
    Austin, TX
    Man I feel like a bum when all I do is ask a question. Hopefully someday I'll learn enough to help you guys out instead of staring at the forum every day with no answers...

    Anyway, I am having a problem with my transmission on my 72 Jimmy that I'd like to diagnose before I get any major work done. The problem is that in the morning, when the transmission is cold, it won't engage unless I rev the engine a little bit. It doesn't seem to matter if I select reverse or drive - I just need to give it a little gas for a second or two and then it engages and all is good. Later in the day, while the tranny is still warm, I don't have the problem. I've also noticed that it will hang in second longer than I would expect at low speeds sometimes - it will always shift to 3rd if given a little gas.

    I've checked the fluid when it's warm and when it's hot and it's fine. If the previous owner wasn't lying, the transmission was overhauled about 2 years ago.

    Any ideas?

    Thanks,
    Marc
     
  2. blazin72

    blazin72 1/2 ton status

    Joined:
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    Location:
    Oklahoma
    It could be a couple of things.
    First I would change the modulator at the rear of it if its bad it will make it shift funny. Hope its that. if not what does your fluid look like maybe change your filter and when your in there look to see if your fluid has any metallic flake in it.
    If it does more than likely your clutches are burnt,
    Mine use to do that and finally tore it down and my cluthes was roasted.
    Good luck
    Blazin72


    Blazin 72
     
  3. 2quicK5

    2quicK5 Registered Member

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    Location:
    TN
    Replace the filter in your pan first. If you filter isn't clogged then it could be your front pump going out. You can diagnos this with a pressure gage on the pump pressure fitting to measure line pressure.

    John

    1972 K5 Blazer: 400 ci, 4 sp, 4" springs, 35" Tires

    2000 Trans Am, A4
    11.97@114 mph
     
  4. Marc72

    Marc72 Registered Member

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    Location:
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    I will see what I can do about the filter, pump, and modulator.

    Thanks!
    Marc
     

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