I've been chasing perpetual transmission oil leaks on The Crusty Chevy.
I've replaced input seal, output seal, extension seal, yolk o-ring, speedo seal, shifter seal, modulator seal, modulater (diaphragm was leaking, and new one is leaking), pan gasket, straightened the pan flange, dipstick tube, and kickdown seal. All of which were leaking.
Today I dropped it off at a friend's shop to do the dye and see what they can come up with. Discovered evidence that suggests front pump seals need to be replaced.
Sad, because when I had the engine out for a rebuild, it did not look wet and I did not change them while I was in there. And despite still leaking once the truck was up and running, when I pulled the transmission to change the torque convertor, it did not look wet and I did not change them while I was in there. And yet today - I saw wet with my own eyes, right there, from the pump. Grrrrr.
Lots of opportunity for me to change the pump seals, but did I do them just because I was in there anyway? Pffft. No. Why would I do that? Silly talk.
This is why you do that. And now the transmission has to come out. Again.
While you're in there, just change all the damned seals.
good thing it only takes about an hour to drop a trans out of those trucks..
and changing the seal isn't a guarantee that it won't leak- if the bushing in the pump is shot, you aint stopping the leak with a $3 seal..
Now you have me scared from not replacing my hard to access starter on my E36 when I had the engine out. 
When the transaxle was being swapped from my donor car, it sprung a leak at an axle seal at some point. It wasn't leaking before. The first clue was the Redline MT-90 leaking out which is very expensive and hard to get here
I didn't change the seal at the input shaft now that I think of it...
novaderrik wrote:
and changing the seal isn't a guarantee that it won't leak- if the bushing in the pump is shot, you aint stopping the leak with a $3 seal..
It's not the input seal for the torque converter (I changed that - smart thinking me). It's the seal/o-ring/bolts on the pump itself.
But yeah, easy job to do. Again.
An idiot acquaintance of mine did that on his VW, changed the timing belt but cheaped out on the idler pulleys and water pump.....guess what he was doing 2-3 months later. Im one of those people that changes all the small cheap stuff if I have good access to it, might cost me a bit more, but its worth the peace of mind.
This is why I replace seals on everything I can when I have access to it.
