A/T trans leak
 

I have a small leak on the '88 S4 Auto tranny. I cannot see where it is leaking. :( Any suggestions on where a sneaky leak might be hiding? Leak is small, teaspoon or even less every few days. Sure am tired of cleaning it off the garage floor. My usual mechanic can't seem to find it either. All suggestions appreciated.
TIA :bigbye:

I had a sneak little leak from the o-ring for the modulator valve. Took forever to find it!

Such leaks range from pennies to $$$ in the cure: to pin it down, clean the entire area by a spray down with an aerosol can of brake cleaner, then look for the obvious with a running, warm engine.
A common leaker is a loose reservoir cap or the gasket of this cap: when the car is shutdown, the returning fluid would gush out this cap were it not sealed .... now you know why the reservoir is so pathetically small and uniquely positioned! :roflmao:

Pan Gasket, o-ring at the reservoir to the tube, the filler cap, the front torque converter seal, the modulator and its seal, o-rings on the piston covers, trans cooler hoses. It's a short list.

Most common: The reservoir cap and the o-ring at the tube, especially following a trans service. Pan gasket installed wrong after a trans service. (see a pattern?) Then the torque converter seal, which means that the torque tube is disconnected and the trans is dropped down for torque converetr removal. Theres a list of WYAIT stuff that goes with this, including TC bearings, trans oil pump o-ring, and possibly a rebuilt torque tube if it's noisy or due. The other stuff seems to be random/luck/whatever.

There's a pretty good trans guy on this forum who may jump in with more/better advice.

Right on Bob, reservoir cap should have an o-ring, most have been lost over time. You will have a tough time finding one that fits right except the Porsche $$$ one.

Auto transmission fluid has great capillary action, give the tranny housing a good cleaning and then you might be able to start pinpointing the area.

Chris

Safely raise the car, clean the transmission, with the engine on, transmission in gear wheels turning; lay under the car and you will find the leak. If it does not leak running let it sit with the engine off.

Joe.........I had a small leak also............turned out to be the drain plug on the torque convertor.

Thanks to all for your great suggestions. I will let you know what it turned out to be.

Yours for a cleaner garage floor. :bigbye:
JF

Joe did you solve the problem? I am a Portlander with the same problem. The shop I use could not ID the source but said trans. removal was required. Hate to go to that expense just to keep the floor clean. I also now have a gear oil leak as well. Two nice multi-colored little puddles overnight.

Jim and all.....
My A/T Leak was from the piston cover on front brakeband in the trans. According to the shop, it needs to be replaced.

Approx labor $225
Approx parts $ 50 - $100

I will get it done the next time it's in the shop. Thanks for all the great advice and suggestions guys. I think having all those possible sources gave the shop the incentive to look hard and find the problem.

Happyy New Year :cheers:

That labor looks reasonable. Cost for parts and fluids will probably be much less.

That front piston B1 cover is by far the most difficult cover to remove. There are two heavy springs behind the cover. The other covers are pretty easy in comparison.

The WSM details removing the B1 piston cover, with the transmission removed from the car, using a special tool. Here's the substitute tool that I used:

http://www.harborfreight.com/cpi/cta...temnumber=5976

But this clamp only works with the valve body removed. In car removal might work with one of these spreaders:

http://www.harborfreight.com/cpi/cta...emnumber=92297

borland
90' S4, Slate Metallic