78' Trans pan leak

[Doug F.]

Im limited to how detailed or how involved i get with fixing up my cars, however I need some advise,, I replaced the transmission pan gasket last summer and still continues to leak some,, what did i do wrong?,, plus ,, i continue to re-tighten the bolts but that dont help,, Im sure as thats where its leaking from as you can see it seep out from around the bolts and the gasket that sticks out some,, any help is appreciated,, doug

[Joe L.]

Re: 78' Trans pan leak

Doug-----

My guess, it's one of the following:

1) The gasket surface of the transmission pan and/or transmission gasket surface was not free of all former gasket material and/or debris;

2) The bolts were not tightened evenly and to correct torque in a crossing pattern;

3) The gasket was not installed correctly;

4) The gasket is inferior.

[Robert S.]

Re: 78' Trans pan leak

Doug, I would add one more possibility to Joe's list:

5) The pan gasket surface is out of shape from over-tighten some pf the bolts.

Check the surface with a straight edge when you replace the gasket again.

[Joe L.]

Re: 78' Trans pan leak

Bob and Doug------

Yes, that's another very good possibility. In fact, it might not be a bad idea to just replace the pan so that you know that you're starting off with a non-distorted piece. After all, how many times do you want to repeat this exercise to finally get to the bottom of it? The pan you need is still available from GM. It's GM #8641537 and it GM lists for about 42 bucks, but you should be able to buy one for about 30 bucks. It might not be a bad investment.

[Patrick H.]

Re: 78' Trans pan leak

FWIW, I purchased a brand new one from GM in chrome with a drain plug already added, and put it in Dad's car. I then used a gasket from a well know Doctor, and torqued the pan down EXACTLY as it should be done, cross patterned and in steps. The stupid thing still leaks, so I'm not sure a new pan or all of the other things will solve the problem. I've thought about re-gasketing, but for now trans fluid is cheap.

Patrick

[Stephen W.]

Re: 78' Trans pan leak

One thing I have always done with a transmission pans is to use a ball peen hammer to gently tap all bolt holes back into position. With the pan edge supported properly and the ball end of the hammer in the hole ( gasket side) Tap gently with another hammer. Your not trying to "dimple" the surface but correct it because it is distorted from the bolts being tightened. If the pan flange is really distorted then do as Joe suggests and buy a new pan. Make sure your new pan is not distorted by rough handling. Place that pan on a flat surface to be sure the contact surfaces are level.

[Scott C Pfuehler]

Re: 78' Trans pan leak

Doug, check the shifter shaft seal on the drivers side of the transmission right above the pan rail. This can leak and usually does and it will look as if the pan gasket is leaking. New seals are available at auto parts stores. The seal can be a challange to get out and reinstalled but you can do it. Scott

[Joel A.]

Re: 78' Trans pan leak

There are even more places to check for leakage that may appear to be from the pan. The accumulator on the pass. side has an o-ring that will dry up/shrink with age, and leak onto the pan rail. Ditto for the filler tube, and the T.V.(kick-down) cable, as well as the modulator. If the pan leaks repeatedly, I would replace it. They can get hairline cracks in them that leak. Always make sure the suface of the trans and the pan is DRY when installing.
As far as the chrome pan leaking....get used to it!(or grind the chrome off of the gasket surface).

[Doug F.]

Re: 78' Trans pan leak

gOT IT!!!! fixed that is,, pass side above the pan , bolt was loose,, thanks guys,, d