Th400 Trans Leaking

My Pontic has been siting for awhile, this morning I was thinking of getting it going so I lifted the car to see it leaking around the pan. I had changed the filter and fluid with a test drive for a few miles and that was it as far as use is concerned. I used a Fel Pro gasket and properly torqued all the bolts to spec. I learned the hard way once over tightening steel bolts on an aluminum case! Should I have used some sort of gasket seal? I did check the pan before reinstalling to make sure it was flat.
Confession: It was a bit over-filled with ATF and I planed to pull a pint or so out through the dipstick before I ran it again. That shouldn’t have caused the leak right?

Thanks for your help.

Rich

no it should be fine, but next time you have the trans oil PAN OFF, WHY NOT WELD or BRAZE IN A TRANSMISSION FLUID DRAIN

https://www.etrailer.com/Accessorie...utm_term=4577129470680387&utm_content=General

It leaks, that’s my immediate problem. I torqued it to specs what did I do wrong?

you might not have done anything wrong!
Id suggest a new trans pan gasket, a bit of brush on sealant on both sides of the gasket or a bead of high temp silicone

I generally use a product like these brush-on sealants on both the threads and both sides of the one-piece transmission oil pan gaskets
(yeah it says you don,t need it)

after using a carpenters square

to verify the trans fluid pan gasket surface is flat & square

https://www.summitracing.com/parts/mor-93103

TH-400 repair manual, torque the pan bolts to 144 INCH-LBS.
THATS ONLY 12 FT LBS and I use lock washers under the bolt heads
https://www.amazon.com/Hilitchi-300...R0C7Z5EZMX1&psc=1&refRID=SSB0KBP3VR0C7Z5EZMX1

https://www.lowes.com/pd/Presa-3-8-...054ceb6a258211bda21d8b5f608a31a8&gclsrc=3p.ds

https://www.ebay.com/itm/Presa-3-8-...4b09b7f74a66505b1367|ampid:PL_CLK|clp:2334524

Great info thank you!!!

I have another question.
I noticed that the dipstick shows about 3/4” to 7/8” out the bottom of the tube. That just about comes even with the bottom of the valve body.
Since the transmission filter hangs lower that makes the trans fluid level (when reading full ) completely cover the filter. Is this right?

yes and then some, the pans basically full plus a bit when the trans is not running