: A Little Known Transmission Leak Source

10-04-05, 07:35 PM
If your transmission has suddenly started leaking very badly, you may not have a bad seal. I just replaced my front pump seal and still had a leak. It turned out it was the lockout solenoid, aka TCC Solenoid.
I thought it was the seal because I had just changed the fluid and filter when fixing a short to my lockout solenoid. Turns out once I fixed the short in the solenoid wiring that the solenoid stuck shut. You can tell a stuck solenoid from the car stalling at stops and delayed downshifting, etc. With the solenoid stuck, the fluid in the torque converter can't run back into the tranny after shut off, and the easiest route seems to be through the front pump seal where it then leaks out from the transmission inspection cover on the bell housing.
There is not a lot of info on this. I reasoned out this theory, but the only info I found online was a person who had a similar problem with this 86 Monte Carlo. He had the tranny rebuilt twice and the torque converter replaced once but still had the leak and delayed downshifting. Further research and I realized something. Transmission shops and experts do not tell you that this is possible. Search for transmission leaks and you are not likely to find anything about the TCC solenoid being a possible cause.
If your car does not leak while running but dumps a significant puddle when you shut it off then this might be your problem. I hope this helps someone before they go through the trouble of a transmission seal. (Or expense if you take it to a shop.)
I almost had to junk my 83 Seville because the leak was too bad to have the car at my apartments. After two very long days spent replacing the front seal via pulling the motor, I was rewarded with the same leak. I hope some others might be able to spare themselves the trouble I went through.
The solenoid is easy to replace. Just drop the pan and there's two bolts holding it in.
One more thing. I couldn't afford a new solenoid so I had to get one from a salvage. I pulled the pans off of three Cadillacs. One tranny did not have a filter in it at all. The solenoid I pulled from that car tested bad. I suspect that car was there because of transmission troubles which may have simply been a $50.00 TCC Solenoid. Transmission shops will tell you you need a rebuild and will conveniently be more than happy to charge you for a rebuild too.

10-05-05, 12:49 PM
What are the remote possibiliy this is an issue on Ford A4LD's? I had an Aerostar that did that. I was told that front bearings were the big issue. But it did it when you are driving, would pump out 3-4 quarts and toss it on the exhaust. It is sorta fun to watch though!

Thanks for the post! I would not have guessed that would do it!

10-06-05, 03:09 AM
I couldn't tell you the possibilities other than if it uses a lock-up torque converter then you just might have this same issue. As for me posting, you're welcome. I couldn't not share this info, especially if people are junking their cars or paying for unnecessary rebuilds because of it.

And for other interesting information on this, when I fixed it, I added the usual 4 quarts to start and drove it to warm it up. I kept checking the fluid level and adding fluid without even showing it on the dipstick at the next stop. I added 6.5 quarts total before the transmission was full. I think that the fluid draining out to the torque converter before the repair was not being replaced because of the lock-up also. There's no where else the extra 1.5 quarts of fluid would have gone but the torque converter. Now I'm hopeful that the slight leak I still have is simply because it is now overfilled (I haven't checked the fluid with the transmission up to temp since the initial fill.), but regardless, I'll probably only have to check my fluid monthly if that.
When I did the front pump seal I was suprised that no fluid dumped from the torque converter when I pulled it. Now, it is obvious it should have, but that was the fluid I had been dropping everywhere I stopped the engine. I think the fluid was probably leaking out a vent since the solenoid kept it from draining into the transmission.

My other issue with my caddy has been emissions, but when I pulled the motor to do the seal I think I discovered the culprit. The air tube to the Cadillac converter has been crimped off, and apparently an aftermarket Catatylic converter was installed with the cap for the air tube still in place. It was probably shoddy work from someone trying for an emission waiver in the past or something. Sucks for me to not know this sooner as I did a full tune-up, oil-change, and throughly went through every other emissions component in the past month only to do even worse on HC's if that makes any sense. The car only has 110k miles and runs like a top. (Albeit a factory under-powered top.)


03-20-07, 07:59 AM
I'm a little confused. You said that when the solenoid is stuck, the fluid in the torque converter can't run back into the tranny, leaving the torque converter full of fluid. But then you said you were surprised that no fluid dumped when you pulled the torque converter. I thought your previous statement says that a working solenoid will let your torque converter drain back into the tranny, so why were you surprised that there was no oil in the torque converter when you pulled it? In other words, in a tranny that is operating correctly, does fluid dump when you pull the torque converter? Thanks, I'm a little new in the transmission world.

03-20-07, 10:31 PM
Which trans are you talking about?

03-21-07, 09:36 AM
I think the car in question was a 83 Seville, THM325-4L....