I have a th350 that I cannot stop from leaking. It leaks on the front edge of the pan. It’s a brand new nice aftermarket extra deep pan. I’ve tried everything I can think of and it still leaks!!!

Any ideas?

Is it a cast aluminum or stamped steel? If it's steel, it's possible that the bolt holes are dented in slightly. Never been a fan of steel pans just for this reason...

For one thing use about 1 quart less fluid. Typically the fluid level is supposed to be at pan line. With deep pan you have more fluid you can be a little lower where it seals better and still have more fluid than stock.
Check and make sure pan surface and case is flat. If it is aluminum and has a little imperfection us a file or flat sandpaper and get it flattened out.

You may need some RTV on the bolt threads that open on top. Fluid may be traveling around the bolt hole.

There is a newer type pan gasket that seals better after it gets hot, looks like regular cork type gasket but it has some heat activated glue that is supposed to help.

Use an inch / Lbs Torque wrench to tighten the bolts. Too tight and it bends pan and does not seal as well. Too loose and it does not seal well.

Check your pan for cracks, have seen some cast aluminum pans have cracks.

Lubelocker for the Win

Many pan gasket fixes turn out to be the shift shaft seal or the dipstick tube.

When I was a kid, I worked in a transmission shop, I can't tell you how many "pan leaks" were the pump o-ring. Take a inspection mirror and look behind the converter at the base of the pump. also make sure the pump bolts are tight.


Joe

A hack for oil leaks like transmissions is use spray foot powder after cleaning the transmission. The powder will show the trail of fluid.