leaking th400
 

Fresh unit, deep pan...leaks out a qt. just sitting there, not running. have tried new pan gasket, new o/ring & a touch of silicone on dip stick tube & modulator valve. have tightened all fasteners and cant see any obvious spots...any idea please? how aggrivating !

Re: leaking th400
 

I chased something similar. It was my deep aluminum pan. I put it on a machined flat surface and found it to ever so slightly rock back and forth. Had it machined flat and solved the problem.

Re: leaking th400
 

If it leaks that much, clean it with starting fluid/ brake clean, put a piece of paper down and wait for the drip.

Re: leaking th400
 

Also look at all the front pump bolts for wet

Re: leaking th400
 

I'm assuming the trans.isn't overfilled.The best thing would be to get the car on a hoist,and as stated check the frt. pump and converter seal,also the weld around the hub on the converter.Also the gear selector seal, and look if there's any fluid around the vent on top of the trans...gsa612

Re: leaking th400
 

checked the pan its flat. going to scuff both alum. surfaces, found a thicker gasket @ .065" compaired to the first one @ .045"...and a thin coat of RTV.

Re: leaking th400
 

A quart from the pan is a lot. Overfilled would make sense. Usually silicone doesn’t work with ATF. You need to pinpoint where the leak is. Do the front pump bolts have sealing washers on them?

Re: leaking th400
 

The torque converter is draining back into the transmission. It will drain fluid until it reaches half way down. There are two fixes. Number 1 is to pull the transmission and replace bushing in front pump and the seal. The easier fix is to remark the dipstick lower to the amount the depth the new pan added. If the deep pan is 2" deeper, then mark the dipstick that amount lower. That way you will have the same amount of fluid as original with the shallow pan. That gives enough room for the torque converter to drain back into the pan. The leaks are showing up because the fluid level after draining back is going above the pan rail.

Re: leaking th400
 

Did you reference the mark on the dipstick related to the pan rail when the pan was off?

Re: leaking th400
 

Make sure the pan is flat.