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Tranny pan leaking....again!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 88K5Jimmy, Apr 18, 2002.

  1. 88K5Jimmy

    88K5Jimmy 1/2 ton status

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    I have changed the tranny fluid (700-R4) twice now because the pan won't seal back up. I used new gaskets and torqued the bolts to the proper specs and it is still leaking. Would two gaskets do the job or just make one big rtv gasket?

    Thanks
    Ross
     
  2. wayne

    wayne 3/4 ton status

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    Is it leaking right from the start or after a few miles? If it is leaking right from the start check to make sure the pan is good and nothing is wrong with the mounting surface on the trans. I use just a little Permatex on mine. I put it on with my finger and spread it real thin. I also use some thread lock on the bolts. Use the removeable kind.
     
  3. Sandman

    Sandman 3/4 ton status Author

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    I had the same problem so I gave up and ordered an aluminum pan from summit. It gave me better cooling, a little extra capacity, a drain plug, and it has a nice thick lip that sealed up on the first try. It even came with the longer bolts. Cost about $80.

    Mabey you could try siliconing the gasket.
     
  4. 76_Cheyenne

    76_Cheyenne 1/2 ton status

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    Your problem could be coming from using silicone on the gasket. You never want to do this because the tranny fluid will break it down and ruin the gasket and possibly clog your transmission. If you need some hlp holding the gasket to the pan, use a little grease but never use silicone!
     
  5. bigmack

    bigmack 1/2 ton status

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    Your pan may be bent or warped, I never use silicone on mine. Usually if you get a cork gasket the holes in the gasket will be small enough to hold it to the pan with the bolts before installation of the pan.
     
  6. 88K5Jimmy

    88K5Jimmy 1/2 ton status

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    I haven't used silicone and a gasket at all. It doesn't leak right away it take a few miles and couple of days to start leaking.

    Thanks
    Ross
     
  7. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    I had the same problem with my TH350...I even tried double gasketing it at one point with no luck. I ended up going to the junkyard and pulling the one in the best shape I could find on one of their TH350's and cleaned it out really well used a new cork gasket and bingo, it worked! If you do this bring some carb cleaner with you it gets really messy!
     
  8. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Maybe it's not the pan leaking...maybe it's the pump cover. I had a pump cover leak and the fluid would cling to the front and come down on the front lip of the pan. took changing the pan gasket 3 times before I figured out what was really leaking. I also had a 1-2 shift acumulator Cover o-ring (TH350) start leaking on me and it looked like a pan gasket leak.
     
  9. 88K5Jimmy

    88K5Jimmy 1/2 ton status

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    Sorry I don't know, but where or what is the pump cover?

    Thanks
    Ross
     
  10. K10ANDYKHAMNIC

    K10ANDYKHAMNIC 1/2 ton status

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    it is behind the torque convertor , u would have to pull the trans to fix it if that is the prob. pull off the inspection cover and you might be able to see if that is the prob
     
  11. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    What K10 said. Pull the cover an look. that's how I figured it out on mine. Will have to remove the transmission if it's leaking from that to fix it. If the 700 is naything like the TH350 that cover comes all the way down to just above the pan. At rest the fluid level is part way up the cover. I could park our truck nose up and it wouldn't leak. Park it level and it would loose about 1/2 a quart over night.
     
  12. Storm Trooper

    Storm Trooper 1/2 ton status GMOTM Winner

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    I always use Permatex High Tack on almost all gaskets. I have built motors, used it and never had one leak even after years (I hate leaks!). Make sure you let the gasket air dry for a while before assem. RTV sucks unless you are using it for a top cover bead. If you spray on too much, it will also allow the gasket to push out like RTV does. Good luck.
     

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