Slow Leak around the Transmission Pan

Discussion in 'Transmissions' started by Coyote-Walker, Sep 5, 2010.

  1. Coyote-Walker

    Coyote-Walker New Member

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    Hello all, I just recently was gifted with my grandmothers 1973 Ford Maverick. It runs great, and it's all orginal. We put in new oil, new tired, and put a new gasket and filter in the transmission. I drove it from Fort Worth to Waco and it drove great the whole way here...then we parked it and the next morning we discovered that all the transmission fluid had leaked out! Upon some work and careful watching we've figured out it's a slow leak from around the pan edge, with one drop falling about every five seconds. We'll be able to get it back to Fort Worth by simply filling up the tranny since it still runs great, shifts fine and everything, but we need to fix this problem before we go to Colorado on Labor Day!

    Does anyone know what it could be? I think maybe the bolts that hold the pan on just need to be replaced, you think it could really be that simple?
     
  2. greasemonkey

    greasemonkey Burnin corn

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    Pan gasket or dipstick tube o ring is most likely the cause. More possibilities but those are pretty common.
     
  3. Coyote-Walker

    Coyote-Walker New Member

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    The pan gasket fit just right, do you think maybe it just wasn't thick enough? Where's the dipstick o ring?
     
  4. yellow75

    yellow75 MCCI Oregon State Rep Supporting Member

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    Dipstick o ring is at the base of the tube the dip stick goes in in the transmission you will have to take the dip stick tube out to replace o ring, you also may have over filled the transmission with fluid, very easy to do. Check when idling in park, probaly not it but worth checking
     
  5. ford84stepside

    ford84stepside Lone Wolf

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    You may have overtighted the pan bolts when you put them back, bending the pan flange. If it's coming between the pan and gasket, you will need to pull the pan again. Put the pan flange on a hard flat surface and take a hammer and flatten the flange, especially around the bolt holes. Also, the gasket could have slipped. I always take sewing thread and tie the gasket to the pan holes in about 4 places, that way it can't go anywhere until all the bolts are in place.
     
  6. Coyote-Walker

    Coyote-Walker New Member

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    I feel like an idiot. Yep it was over filled. We'll keep an eye on it during the drive to colorado and give it a real good check once we get there, but I think that's all it is. My daddy put the pan back on and he's done it dozens of times before so i don't think he over tightened it. The o ring is something to check as well, but it's never leaked before. I think it'll make the trip just fine, it's never given my granny or its first owner any trouble. :) Thanks everybody!
     
  7. Bob Wiken

    Bob Wiken Chronologically Gifted

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    "...I always take sewing thread and tie the gasket to the pan holes in about 4 places, that way it can't go anywhere until all the bolts are in place. "
    __________________

    great idea. Thanks. I'll remember that
     
  8. PaulS

    PaulS Member extrordiare

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    When replacing the pan gasket make sure the pan rail is straight.
    That means hammering out the dimples from the last time it was tightened. It means making sure the pan isn't twisted. Check it with yard stick or anything that has a straight edge.
    Clean the pan rail and the transmission mounting surface. If necessary go over it with a hard block with sandpaper and some laquer thinner to get it clean.
    If all the surfaces are perfect and you know that you are not overtightening the gasket you can put it on without any sealer. If you and the two surfaces aren't perfect (like me) use a thin (.010") coat of Loc-tite #518 flange sealer on both sides of the gasket and then install it.

    The dipstick tube is a monster - they crack in the O-ring groove and it is hard to spot. The O-ring can get cut when it is installed and you don't know until it leaks and you pull it out that you find it. Some use grease to lubricate it which is ok, but I use Loc-tite #518 flange sealer on the O-ring as lubricant for installation and to seal any crack that I missed on my inspection.

    ATF will turn RTV (silicone) into jelly that will get into and block passages and ports throughout the transmission. NEVER use RTV on an automatic transmission!

    Pan leaks can be a symptom that is from a lot of different places. The dipstick tube is just one. You can add to that:
    vacuum modulator O-ring leak
    cooler line and fitting leaks
    Manual lever (shift lever on the transmission) leaks
    Kick-down shaft leaks

    The easiest way to track leaks to their source is to use a black light. You can buy a 24" flourescent black light pretty cheap and trace the fluid (it glows) from where it puddles to the source if you remember that you are tracing it forward and up from where it is puddling.
     

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