Tranny leak

Discussion in 'The "Juice Box"' started by 83regal455, Sep 26, 2004.

  1. 83regal455

    83regal455 Guest

    I have a TH400 with a B&M race kit in it. The tranny leaks, i have changed the gasket three times to no avail. The modulator is the first to get wet. I have changed the modulator twice and made sure the o-ring wasn't stuck or cracked. Still leaks :af: Any thing else i should check.

    Thanks
    Dustin
     
  2. MeanBuicks

    MeanBuicks Scaring the neighbors.

    Some other areas to consider would be the dipstick tube (or tube seal) and the cooler lines/fittings. The dipstick tube or steel cooler lines can crack and leak so it may not even be a gasket or seal.
     
  3. 83regal455

    83regal455 Guest

    I checked the tube it's a tight seal and i replaced the steel fittings with brass barbs for quick changes in the lines. They also are not leaking. I was wondering if anyone has any problems with a vacuum modulator?

    The tranny has a B&M race kit in it. The kit came with a modulator plug. With the plug installed the tranny wouldn't shift out of first gear. I put a modulator in, didn't hook the vacuum up to it (suggest by B&M tech) and it shifts.

    The main line pressure at 3500 rpms on the tranny dyno is 184psi.
    The main line pressure in reverse is 591psi.

    Are these normal, low, or high?

    Thanks
    Dustin
     
  4. MeanBuicks

    MeanBuicks Scaring the neighbors.

    591!! :eek2: That'll break a case.
     
  5. 83regal455

    83regal455 Guest

    it broke the gauge on the tranny dyno and scared the teacher a little bit. The guy from the tranny shop was a little worried but said i should be okay. I don't know why it's so high. The teacher at the tech school checked it every step of the way.

    Thanks
    Dustin
     
  6. frtlnrbuick

    frtlnrbuick Midwest Mafia

    First, that pressure is very high. Are you sure the brass fittings are not leaking when the trans is in operation? The steel fittings are not tapered (NPT) threaded, hence the gasket. Did you re-tap the holes prior to installing the fittings?

    Second, what type of pan are you using? If it is stock, did you make sure the rail of the pan is not warped? Warped is not really the word, but, the pan will deform around the bolt holes and when you tighten the bolts the rest of the gasket is not compressed enough to seal. Take the pan over a solid surface, I use a concrete step, and with a ball-pein hammer, lightly tap the holes down to flush or a little below. Then remember to not overtighten the pan, IIRC the torque spec for those bolts is only 5-10 lbs.ft.

    Jim
     
  7. 83regal455

    83regal455 Guest

    our local tech school and my best friend (student) built the tranny. I know the teacher and he said everything was done to a T. I wll have to check agian i guess. I haven't checked the pan for trueness yet so that's next.

    Thanks
    Dustin
     
  8. 86regalwith455

    86regalwith455 Well-Known Member

    I have seen oil go though aluminum before, if the casting is puorous.
    Dean
     
  9. BirdDog

    BirdDog Well-Known Member

    Tranny leaks can be a pain. They can be very difficult to locate.

    What I have done in the past is: throughly clean the tranny with carb/brake cleaner. Get several cans of the stuff. After tranny is clean, check it every day and/or after every use to see if you can tell where the leak is coming from. Re-clean tranny after every inspection to ensure that any fluid present is "fresh". It may take several attempts to pinpoint the leak. You can easily go through several cans of "cleaner" doing this and it may take some time, depending on how bad your leak is. But this is a rather effective means for finding leaks. It will take some trial and error.

    Remember, while driving, the force of air can blow the fluid to areas that are not the cause of the leak. Keep that in mind. :TU:

    I have won several "battles" with tranny leaks this way. Good luck. :TU:
     

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