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TH350 Tranny Problems

Discussion in 'The Garage' started by donoh, Apr 22, 2005.

  1. donoh

    donoh Newbie

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    I have a question/problem. My tranny has been releasing fluid out the filler tube. At first I thought it was overheating, then today I discovered exactly when it was doing it. This is the second time this happened. The truck was parked all day, so I know it was no hot. I backed the truck up to the garage door,(approx. 45 ft), and shut it off. I went inside to get a jack. I then proceeded to jack the right rear tire off the ground, that's when I heard fluid hitting the ground. I lokked under to see a steady stream flowing on the ground. It was so much that I had time to walk around the truck to release the hood from inside the cab, oopen the hood, and verify that "Yep" it is definitely coming out the top of the filler tube.

    I have never seen this before. The truck was not hot, nor was it running at the time. It did, however, put a lot of fluid on the ground.

    Does anyone have an idea of what may be wrong? Should I be looking for a different Tranny?

    Thanks for you help.
     
  2. 1979jimmy350

    1979jimmy350 1/2 ton status

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    you could have a cloged vent tube maby. Have you done any thing to the tranny at all is it a newer rebuild? It could als be overfilled. Rember you need to check the fluid level with the truck running
     
  3. donoh

    donoh Newbie

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    The tranny is all original 1976. There is a chance the vent on top of the tranny could be clogged I suppose. I will check that out. The level is correct. I made sure if that when it happened the first time. However it is probably low now.
     
  4. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    yep clogged vent tube. the little bit it ran heated the air up enough that when all the fluid returned to the pan that it pushed it right up the tube. if the vent tube wasn't plugged the air could have excaped threw the vent.
     
  5. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    I rebuilt my th350 a few years back. after i was all done it was awsome except that it would puke tranny fluid once in a while like you're talking about.. eventually caught on fire and took 2 extinguishers to put out the 'dripping lava' off the headers. :blush:
    I figured out that when i rebuilt the tranny somehow i misaligned the front oil pump gasket so the vent tube was clogged but everything else worked.

    The way to diagnose this is get an air nozzle, stick it down the dipstick tube and have someone blow the air down the dipstick.
    one of two things will happen. The fluid will come flying back out the dipstick and all over you or whoever you had do that test for you. = Clogged vent.
    or #2 nothing exciting happens and you can hear (and feel) air escaping out the vent tube on the top drivers side of the transmission case.
    If it turns out the vent is clogged you can try getting something flexible like a piece of wire and sticking it up the vent to try and clear the passange. You might get a little bit of that junk in your tranny so its probably a good idea to do a fluid change.. but that has done the trick before.
    Another guy on here did the same as me and i saved him the hassle of pulling the tranny/tcase and removing the front tranny oil pump to change the gasket, with my "shove a wire up the vent tube" method. :rotfl: :thumb:
    let us know what you find & good luck.
     
  6. donoh

    donoh Newbie

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    OK Guys. Thanks for the help. I just got back in from unclogging my vent tube. I looked at it and all I could see was, the end of the tube filled with gravel road dust. Packed full to the end. I cleaned it out with a wire. Than I had my 6 year old boy (real expert) lay under it. He told me that "there was a lot of cold air coming out" when I blew some compressed air into the fill tube.

    I am pretty sure this will solve my problem. I will keep you posted, and help you guys when it is my turn.

    Thanks for the help.

    Don
     
  7. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Sweeeeet. :thumb:
    I'll bet that did the trick. :cool1: To prevent it from happening again, you could run a small rubber hose from that vent outlet up high into the engine compartment or something to keep the vent line clear and so no water/mud could get in there.
    Rock on!
    :thumb:

    Ryan
     

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