Transmission Leaks

For as long as I’ve owned the car, the automatic transmission leaks. A lot. I’ve previously tried a silicone gasket on the pan, which didn’t work because the pan wasn’t perfectly flat, or the bolts were over torqued. Either way, I decided to try my luck at fixing the leaks again.

The leaks are everywhere:

March 28^th, 2021
Here’s how much it leaks in 20 hours:

I removed the pan, disconnected all the wiring connections, and started cleaning all the surfaces:

I bought some steel brackets and clamped them in a vice. This was used as a flat surface to hammer the pan as flat as possible.

I brought my used O rings to the hardware store, and after comparing new ones, I purchased an assortment:

After test fitting a few, I used the tightest fitting O rings. That should work, right?

The coolant pipes were in the way of the transmission pan. I drained the coolant and disconnected the pipes.

I scraped off the old RTV with plastic knives, and my fingernails to avoid gouging the transmission casing. I then cleaned the surfaces with lacquer thinner. I purchased Permatex Automatics Transmission RTV Gasket Maker. I resealed the dipstick tube with the new RTV. I used two beads of RTV around the pan, without a gasket. This should work, right?

April 27^th:
It wasn’t easy, but I got the pan on, and torqued the bolts to spec with my inch-LB torque wrench. I gave the RTV several days to cure.

May 5^th:
Before I even put any fluid in the trans, it’s leaking around the casing. I don’t understand this thing. I know the torque converter stores fluid, which would probably drip into the pan. But my transmission is sweating ATF. Not good…

Then it was time to fill and bleed the coolant and put the car on the ground.

May 14^th:
I was now able to start the car, and warm it up. After checking the ATF fluid level several times, I finally found the correct level, and was able to get the car in gear. Time to drive! I haven’t driven in about a year or more!

My 5 mile test drive went great! The car shifted smoothly, and I didn’t see any fluid on the ground in my rearview mirror. I returned to my garage to inspect:

I’m glad I didn’t drive far. I was defeated. I considered trailering the car to DMC-MW. I solicited advice.

May 29^th:
After a several days, I went back into the garage to inspect. After a little bit of prying, the pan came off with most of the RTV. Barely any RTV stuck to the transmission:

In the past year I’ve spent more on ATF than on gas for the Delorean.

I decided to try again. I purchased a nitrile bonded cork gasket – i.e. a modern version of the original cork type and much more flexible. It’s supposed to seal very well. I also a high-tack sealant to help the gasket stick to the pan, but opted not to use it. Then I waited too long to return the sealant, so it’s mine now!

Someone suggested using Permatex Anerobic Sealant. After searching stores, I ended up with two different sized tubes. Once again, I waited too long to return one. Anyway, I used the sealant around the heads of the pan bolts.

I caught some of the transmission fluid in a clean container, filtered it with a shop towel, and reused it:

Torqued the pan bolts. Check the fluid level. Time to drive! This should work, right?

June 3^rd:
The test drive went fine. Except I still had a decent leak:

June 12^th:
After a few more days, I once again raised the car, shimmied underneath, and inspected. In my tight working space, I’d mistakenly caught a zip tie between the pan and transmission:

June 16^th:
After loosening a few bolts, I pulled the zip tie out, and retorqued the bolts.

I’m done trying to fix the leak for this year. I’ll try again someday. Until then, I’ll keep emptying my drain pan on the floor of my garage.

Costs: