Ok.....here we go......the other day I planned on doing a trans service on my Bronco....its been about a year of hard NYC traffic.....and playing.

Went to the Ford Truck dealer and bought a gasket and filter for a E4OD, and the parts guy handed me a cork gasket......my friend said no no no.....we want the rubber one...its better (bad move). Well a hour or so later....after draining the torque converter and trans.....cleaning the mating surfaces and reinstalling the "new" rubber gasket.....and dumping in 15 Qts of Mobil 1 Synthetic ATF...(read $$$$$)......I am just backing it off the lift and my helper starts telling me to shut it down.......its PISSING ATF at the rate of $6+ per quart all over the shop floor.
OK.....its VERY obvious that the gasket aint holding........go get more $$$ATF, and a cork gasket.........dry as a bone for two weeks now.

SO.......just in case the parts guy hands you a rubber gasket (the parts computer says that either one should work.....and the rubber one is more money!) for a E4OD........make sure you tell him you want the cork one only!!!!

Anyone else have this happen?????

 

The cork version will absorb the first few drops of ATF and create a suction between the mating surfaces and the gasket itself whereas the rubber one won't. The rubber one won't get hard and vitrify as quickly as the cork one but the inital seal is harder to maintain. There is a gasket conditioner you can use with rubber gaskets to help keep the situation you had from happening. Usually requires letting the gasket sit there with the conditioner on it for a few minutes before finishing the install. New rubber gaskets are often covered in a powdery compound that is there to keep new rubber from adhereing to the packaging. A good cleaning before the install can sometimes help alleviate the problem as well.

 

This is an old post, but I wanted to reply just in case someone searches and stumbles upon this thread (like I have).

I just found out that there are 2 types of transmission pans.

One with raised bolt holes and one with a flat surface.

So you have(had) the one with raised bolt holes, which the rubber gasket doesn't fit flush on.

The one with the raised bolt holes are only compatible with the cork gaskets. (no one carries the cork anymore)

The flat ones you can use the rubber.

 

The Fram filter kit has a cork gasket that is awesome, just had to swap mine out and ended up with a crappy rubber one that drips