Ever had or heard of a warped trans oil pan?
 

I have a pretty serious trans leak at the passenger rear corner of the trans oil pan. It is dripping from the bolt. I replaced the gasket but the leak is still there! Is it possible the pan is warped, maybe the tab with the bolt hole is bent? Visually it looks fine. Trans works great. I cannot trace the leak from anywhere else. I cleaned the area and it appears that it is in fact leaking at the gasket. Are there any connections/seals above the rear passenger side of the trans that I would not be able to see without dropping it?

I can't say from years of experience, but from the one time I dropped my pan and reinstalled it I had a leak from the right rear corner. I believe overtightening is the culprit. I removed it again, set it on a bench and tapped it down slightly with a hammer and put it back on, this time just going a bit past snug, and it no longer leaks.

What did you tap with a hammer? The metal tab the bolt goes through?

Thanks for the response.

yes. When I overtightened it it bent it in towards the trans, I tapped it back where I thought it was to start with. When I looked it over, I saw I had bent them all a bit.

Take the pan off and put it on a flat surface - like a glass coffee table. You should be able to see if it's warped or not.

If it is, You should use a short piece of 2x4 and a hammer to tap all sides back into "flatness". Just hammering at one hole could cause the metal to bow out in the other direction.

Obviously, don't hammer on the glass coffee table.

If the pan isn't the issue, hold up the pan to the trans and see where the gap is. I don't think there's much you can do about it if the trans mating surface is slightly warped other than using thicker or multiple gaskets and using some "right stuff" or similar MB sealing product.

Make sure you follow the correct tightening sequence, as well - pretend it's just a big wheel and get as close to a star pattern as possible. Also, tighten in 2-3 stages; this will insure equal torque around the entire pan.

Good luck!

Yes, happened on mine last year, when the original pan was 20 years old. I don't have any explanation for why it happened, no obvious trauma to the part, so I imagine it was age and the fact that the pan has been removed and re-installed a number of times over those 20 years, that it might have been incorrectly torqued at some point. A new OE pan fixed the leaking.

I've had it happen on two of our cars.....one I had to buy a new pan for, the other I had to do a swap with a part I had in inventory.

On my 300SE, I could have sworn that the culprit was the pan, but it actually turned out to be the banjo fitting on the cooler line. The fluid was just dripping down in a way that made it seem like it was coming from the pan. Worth a check before you pull your pan. In my case, a 3/4 turn with a wrench solved the issue.