If you own a manual trans van, this will mean very little for you, except as a 
horror story, or a good laugh.

Over this past summer I tried fixing the mystery leak on my '85 auto trans. The 
actual trans is from a '91, but that matters not. Both of the transmissions 
showed the same condition, to whit:

There was a constant leak in the trans. Sometimes not much, sometimes quite a 
bit. (Like a pint in 100 miles.) I used every diagnostic trick I knew to track 
this down. I replaced the pan seal (x3), the�governor cover seal, even had to 
replace the 2nd-reverse actuator piston. Did not seem to make much difference. 
The leak still appeared. My fluid level went down. I used more trans fluid than 
engine oil. And no,�it was not going into the final drive.
Despair.
I finally gave in, and was going to go for the dreaded coolant-to-trans 
intercooler, figuring that the o-rings in there had given up. Ran the van up on 
ramps,�and pulled the forward trans mount. When I tipped the trans and engine 
down, to get access to the forward mount bolts, a rush of fluid greeted me. I 
had not opened up anything at this time, just changed its position. 

Huh?
Well, after poking around on the installed trans, and on the 
extra�transmission�on the stand in the garage, I found a small steel plug that 
was used to block off a drilled manufacturing access hole on the top face of the 
trans, at the forward edge, next to the trans mount. This vertical hole allows 
passage of fluid from the body of the trans back into the pan, as an internal 
drain. The thin steel plug was placed at the bottom of a shallow hole, and since 
crud will collect in any depression, it did. The hole was about half an inch 
deep, and was filled level with oil-soaked crud. And, as it held water and 
electrolytes too�(Michigan vehicle),�gradually the plug was perforated. The 
passage under the plug itself is not under any real pressure, but the passages 
that lead into this passage are under operating pressures, so the plug is always 
getting some fluid pushed into it. And then out of the trans. Always at low 
volumes, and no real direction. But always, if the van is driven.
So.
I removed the remains of the old plug. It was rotted almost completely away, on 
both transmissions. I measured the diameter of the hole. It is a stepped 
diameter, with a larger diameter at the upper, plug end, than through the rest 
of the body of the trans. After some research, and multiple trips to several 
transmission shops, including VW/Audi specialists, I got nothing. No one had 
heard of such a thing, let alone tried to fix it, or find parts to fix it. I 
figured that just being a steel plug, a regular engine block freeze plug ought 
to work.�After asking at the local Auto Parts store - not a chain, but an old 
fashioned Parts Store - we found a freeze plug that was compatible. A Dorfman 
555-015, at 0.923" diameter. After carefully driving that into the hole, no more 
leak. The cost of the plug was 83 cents.

So, if you have an annoying, anonymous leak in your auto trans, it may just be 
there.

Evan Mac Donald 

"...in the absence of facts, myth rushes in, the kudzu of history."
-Stacy Schiff