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TH350 Front Pump torque specs

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Erich_in_AZ, Feb 20, 2003.

  1. Erich_in_AZ

    Erich_in_AZ 1/2 ton status

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    Anyone know what the torques specs are for the pump to case mounting bolts on a th350? I've been fighting with a leak there forever, and we are about to pull the tranny and re-reseal it! /forums/images/graemlins/angryfire.gif

    I already did this once, but it still leaks bad! Maybe I screwed something up when I did it last time, but the procedure seems pretty simple. Here are some pics from last time, maybe you guys can see something wrong that I missed.

    http://www.wheelingarizona.com/tech/pump_seal_replacement/index.html

    Thanks
     
  2. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    The front oil pump to tranny case torque spec is 20 ft./lbs.
    /forums/images/graemlins/thumb.gif
    I'd go a little tighter just because i don't want it to leak!

    One thing i will add is when re-installing the pump, lube up the gaskets first with tranny fluid especially that rubber o-ring or lip seal around the pump. When you get the bolts started, then get a pick or something sharp and work that lip seal all the way around to get it to go inside the tranny case better.
    Good luck man!
     
  3. Erich_in_AZ

    Erich_in_AZ 1/2 ton status

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    Thanks. I'll keep a really close eye on that lip seal this time. Getting this to stop has been a real PITA!
     
  4. the professor

    the professor 1/2 ton status

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    If you are leaking from around the front pump, it IS NOT because the bolts are loose
    --
    Make sure it is not comming from the converter seal, a bad pump bushing will make even a good seal leak
    --
    If the gasket were leaking, it would leak into the case..It CANT get past the big "O" ring
    --
    You could talk all the bolts out, and you would get leakage from the bolt holes (don't try it) but NONE from around the pump
    Probable cause:

    It is the big "O" ring
    and/or the "sealing washers" on the bolts

    Both these MUST be replaced every time

    And as was suggested ATF, or Vaseline or even better Door Ease get at autoparts store..I don't think anyone has ever used it for a door..just AT assembly

    The big rubber "O" ring seal, has a teflon insert around the outside and cannot be re-used, it is also very easily damaged..

    Check very carefuly for damage to the case where the O ring contacts..sand out any grooves or burrs..you can go pretty far, as long as the imperfection is sanded out over a large area...to alow the seal to contact it properly.. .If they are realy, realy deep, the case is trash..

    The sealing washers are alum with a rubberlike coating and are distroyed every time you use them

    There is a possiblity that you or someone else had the front pump apart...the two halves might not be perfectly aligned, creating a edge around 1/3 of the pump, the will score the case and cause the o ring seal to leak

    /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
     
  5. Erich_in_AZ

    Erich_in_AZ 1/2 ton status

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    It's definantly not coming from the TC seal. That area is dry as a bone. It IS collecting on the lip at the bottom and dripping from there, so it pretty much just leaves the pump seal again. I must have damaged it when I installed it, or something like that. I'm considering taking a pump out of one of the other th350's that are laying around my garage 'just in case'. To give you an idea, It leaked about 1/2qt yesterday just sitting in my parking space. /forums/images/graemlins/eek.gif

    The new seal I put in there before had a yellow stripe on the outer ring. Should that have gone on the inside, or does it matter?

    [​IMG]

    Thanks for the help!
     

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