727 Leaking Fluid At Cover Plate

The first couple of startups this season I did not see any leaks. Today I pulled the car in/out of the garage a few times (spring cleaning garage) and I noticed a small puddle of trans fluid. It is coming out of the lower cover. I checked the fluid level and it showed apx 1/4" below the full line (in N engine warm and went through the gears before checking).
Rebuilt trans 3 years ago with apx 1500 miles or so since.
Any suggestions on what to look for?


Thanks

Lower cover? The plate on the front of the bell housing? That covers the front/bottom of the torque converter? Sounds like the front seal has gone bad.

Yes, that one.
Crapt! I remember wiping off some fluid there last fall a few times. Today I found a couple of small puddles (quarter size) after it shut down a few times.
Thanks

If it is not much, could just be from the vent?
If you have to pull it to replace the pump seal, check the converter hub for cracks too. Had one that kept leaking, and finally found the converter hub had a hairline crack.

You can guess at what your issue is or diagnose a litter before yanking it apart. Pull the inspection shield - spray some brake kleen or carb clean inside the bell housing and dry it out reall good. Reach in as far as you can and dry the back side of the converter if it is wet. Then start it up and let it run in park. If no leaks after a while shut it off and let is set for ten or fifteen minutes and check again. If dry start it back up and run it in neutral for ten minutes then again shut it off and check again. If no leaks you can take it for a short drive but keep the engine speed low, come back and check the bell again for wetness. If dry - you're lucky and likely just the fluid burped from the vent. If the converter backside is wet then you have a converter hub crack - not very common. If the bell is wet and the converter is dry you have either a leaking pump seal to the converter (impeller hub seal) or a leaking pump to case gasket/perimeter seal or a leaking pump bolt/washer (again not too common but I have seen leaking gaskets when the bolt is under torqued. Most of this diagnosis is in the service manual.

Thank you! I will try to diagnose tomorrow.

Could it be the o-ring on the filler tube? Much easier to fix than dropping the trans.

I ran my hands up and around both sides and they were dry. It was dripping out of the cover. I was working on the choke setup so I started it up two more times after I wiped it down then parked it to watch for leaks. But I just went out and looked under the car and the floor was completely dry.

So I will get it back in the air tomorrow and dig further in.
Thanks again.

That would result in it dripping from the pan. Not the inspection cover.

Tranman has the right approach.

Update:
I removed the cover and I could not get my fingers in far enough to check out the back side of the TC.
I sprayed the inside of bell with brake cleaner and wiped it clean.
I ran the engine for 5 minutes on fast idle (1300rpms) with tranny in P. No leaks.
I then let it set for 10 minutes with no leaks and inside of bell was dry.
I then ran the engine for 10 minutes on fast idle with tranny in N. No leaks.
I then let it set for 10 minutes with no leaks and inside of bell was dry.
I will not get a chance to drive it today due to weather.

I did drive it up and down the drive yesterday just to get the fluid moving before I pulled it in.
It is strange that yesterday it left 3 quarter size puddles and today it is dry.

Thanks!!

Hopefully it healed itself. Make sure you check the fluid level warm and in neutral - and we assume you have the correct stick for the tube.

Did you back it out of the garage or was it nose out and you drove it out when it leaked?

They don't pump fluid in park. Always check in neutral.

The car was nose in and it was backed up and down the drive a few times to get the fluid moving (first time out of the garage since Fall). It sat out in the drive (rear angled downward towards street) for an hour or so and then I started it back up and moved it into the garage. I was playing with the choke setting so I started it up a few more times until I got it set.
Note: Just before I pulled it into the garage, I did flood it real bad (while in the driveway) and I had to put my foot into pretty hard (in P) to get it started up and keep it there to clean it out. Then I pulled it into the garage and parked it. That is when I noticed the dripping fluid on the floor.

The fluid was topped off last Summer after a 20 minute drive and it was checked/topped off to the line in N. This is the original dipstick for the tranny.

I have attached a picture of the tranny after the rebuild four years ago, ready to bolt back in.
Note: When I took off the cover plate, most of the fluid was on the passenger side of the inside of the cover plate. The fluid was not up on the drivers side of the cover plate. The fluid was noticeable up to the two larger holes on the passenger side of the bell. No fluid was higher than this second large hole up from the bottom.
Hopefully that helps describe it better.

Where is the vent in this picture?

Thank you.

vent is under orange cover at the top of the pump.

Thanks!

That sheet metal shield painted orange covers the vent which is a hole in the pump housing - this is the early design vent. The later and final design has a plastic baffle on the back side (inside the trans) instead of just being open, the plastic vent baffle has a tube like extension that fits closely inside the groove of the front clutch. The later design is less likely to have fluid thrown at it when the front clutch is turning or if fluid gets thrown up from slosh. It's a stretch but when you backed out of the garage that front clutch drum was turning and any leakage from this drum or fluid high in the pan from setting would have been thrown at the vent while backing up - and on a cold day and cold trans if you let it warm up the temperature rises inside the trans and builds pressure. ( that's one of the reasons for the vent to allow pressure balance ). The other thing going on in your case of first start after hibernation - expelling all the air from the converter - it comes out when you fill the converter in any gear position but Park. It had to go somewhere too.
The other design change to prevent fluid burping was to change the drain in the reaction shaft support. The early style drained from a hole aimed at the front clutch. Again, to prevent this burping the later support has a channel cast in it to allow the fluid to drain down and away from the front clutch. Hopefully this leak was a one time event.

Thank you very much Transman!
I will keep an eye on it during my first couple of drives to make sure all is good.

By the way - I'm impressed by that workbench - looks like you or your trans guy is pretty organized - you can't believe how many trashed benches I have seen where a trans tech was working. Nice selection of selective thrust washers too.

It is not my bench. But my guess is, you two know each other. (Rick Allison)

(Some good, long runs(heat cycles)may cure your problem...

Actually, it is the later design with the plastic baffle. The bottom of the casting "hump" that surrounds the vent baffle opening is visible just below the metal shield. (see red circle) Of course, that doesn't mean the plastic baffle isn't broken/missing inside.

Good eye John - I saw the tin shield and didn't scrutinize further.

Thanks again guys!

I finally got to get the car out today and drove it for about 45 minutes or so. Then I let it cool down in the garage and no leaks!!

Thanks everyone!!

Thank you for the update