Date: Sun, 16 Oct 2011 17:05:35 -0700
Reply-To: Evan Mac Donald <evanm@ATT.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Evan Mac Donald <evanm@ATT.NET>
Subject: Auto Trans Leak Location
Content-Type: text/plain; charset=iso-8859-1
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
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