Automatic Transmission

Remove the transmission from the vehicle according to the proceedure listed in the factory service manual.

Take it and a fistfull of money to the Automatic Transmission specialist and ask to have the transmission rebuilt.

While modern automatic transmissions are long serving when they fail, it is beyond the average shade tree mechanic to repair them. there is much that requires specialist knowledge and tools to repair.

Tobugrynbak Is very right. There are many places for hydraulic pressure to leak from inside an automatic transmission. And almost all of them require very expert training.

Why do you think the transmission problem is leaking hydraulic fluid? Most of the transmission failures I have seen resulted from worn friction materials. What is the color of your transmission fluid. It starts off a bright cherry red color. When friction materials wear off, the fluid darkens, and turned brown in color. If your fluid is not as bright as new, it is clutch dust in it. Or if it overheated, it will also darken in color. Overheated transmission fluid will allow rubber internal components to harden and allow leakage internally.

One of the very few places that fluid could leak internally that you can do anything about is the valve body to transmission case basket. There is a VERY slight chance that the blots holding the valve body to case loosened up and there is fluid dumping to the transmission pan instead of being directed to lock up a clutch. You could drain the fluid and save it in a clean container. Check the bolts holding the valve body to case for tightness. If you can turn them with a 3-4 inch long ratchet, that MIGHT be your problem. If so, snug all of the bolts up and replace the pan and fluid, and then retest the vehicle.

This is really a long shot, so don't waste money on new fluid and pan gaskets. If it does work, you can always change them later. (No reason to send new fluid and gasket to the transmission shop to buy them again) Good luck.