TH400 frustration

[lilbowtie]

Got a feeling it's not leaking there. Does the gaskets show signs of leaking?? If you can tell what side that's a plus - Shifter seal, modulator, front seal, gov cover, and dip stick tube all bleed to the pan gasket making it look like the pan gasket leaking.

 

[Texas82GP]

Will the 4L80E gasket fit? I ask because I used the Delco gasket with the aluminum pan on my 4L80E. The Delco gasket was expensive but it seals with no sealer, at least it did for me.

Admittedly, I was pretty fanatical tightening the bolts on my pan. I did it in a criss-cross pattern starting at the center and working outward, and did it in two passes with a 1/4" drive inch-pound torque wrench.

 

[hoffa65]

i thought so too, but its dry there. it starts always somewhere around the pan.


the pan is a cast aluminium deep pan made by B&M. i checked all the surfaces, they are all flat as they should be. excessive pressure would be a sign of overfilling, but the levels are just right, both hot and cold.

Excessive pressure can be a plugged vent hose not over filling, leave the dip stick out and see if it leaks if not the vent on top is plugged

 

[shoedoos]

Next time you have the pan off, take note of the markings on the dipstick. The 'full' line on it is the same level as the pan mounting pad. If you're over filling the trans it is very hard to control leaks. You will also find it hard to control if the car is not driven regularly. The fluid in your converter siphons back and overfills the pan, then the leaks start again, a regular fireup to re-fill the converter will help.....have you looked at the Moroso silicone pan gasket?

If you discover your problem is not the pan gasket, then place a large sheet of cardboard under the trans the next time you park the car and then note where the drips land. The dipstick o-ring, the shifter linkage seal and speedo seal are all likely culprits positioned in different places on the trans.

 

[pagrunt]

One tip for the pan gasket is don't use glues/adhesives on them, I used miltary artillery & automotive grease (GAA) to help hold the gasketin place, seemed to do a good job helping the seal, didn't have to worry as much if some extra made it into the fluid. With the pan & trans gasket flange check the flatness, easy on tighting those bolts in a pattern.