Transmission leak from the front bell housing 727 question

[mr. fix it]

Hi there you 727 transmission experts!

have a look at the photo here and give your advice as to where this leak is coming from.

I have learned that a 727 that sits for more than 3 to 5 days can have the convertor drain back into the case then put the trans into an over filled state causing fluid to leak out of the vent at the front of the transmission in the bell housing.

the convertor seal is good as shown to have a dry convertor

At first glance it looks like the pump outer seal is leaking at the bottom but take a good look at the vent on the left.

There is a small drip of fluid which could be the real cause of this apparent leak.

If it is the vent, is there an updated vent I can use to stop this inconvenince other than putting a diaper under the bell housing?

 

[mr. fix it]

Here's a better view of the vent..

 

[65sporty]

I talked with my trans tech, if the converter drains back it goes into the pan, it will only come out of the vent if it overheats, I would pull the front pump and replace the gasket, pump o-ring, front seal and bolt washers. the washers have seals on them. hope this helps

 

[moper]

You have been poorly educated. At no time can the vent have fuild come out of it from the convertor draining. It can get pushed out at high rpm if the trans is overheated majorly or the level is too high. The fluid level never gets to the vent. So if it's leaking, it's possible from a few spots. The washers on the pump bolts, the seal around the pump that seals to the case, or the pump seal. From my experience I'd say it's probably the pump seal. The fluid that's in the bell gets whipped everywhere and ATF is high in detergents and thin, so the convertor is squeaky clean and the dust get's stuck to the oil covered interior of the bell. As it gets worse it will leak more and more.
On the vent - there are kits to relocate it to the tailhousing but you have to take thje pump out of the tranny to thread and plug the existing vent hole, and the tail housing to drill and tap that.

 

[tallhair]

No offense intended but it is not overfilled is it? Must be checked when warm, and in neutral.

I've read the drain back problem can be addressed by putting a check valve in the return line but have never done that.

 

[70bigblockdodge]

Moper is correct the trans would have to be full to the top to leak out vent. Has to be the seal fluid is getting flung to bellhousing by tc shaft fluid does not stay on tc because of heat and rpm. Pump to case might be leaking but would most likely be more than annoying drip. The suction side of pump might be leaking (its that wider casting bump above the bottom drip) this would cause sucking air when running and drain/leak when shut off, doubtful but anything is possible this stuff is getting old and who knows what chevy creatins have touched it.

 

[66SportFury]

You have it out, so might as well reseal it, clean it up, paint it and put it back in and enjoy. Always start the car in park then shift it to neutral for about 15 to 20 seconds. This will refill the TC. I do it every time with my car. It's a habit of mine now. Let us know how ya make out with it.

 

[mr. fix it]

You have it out, so might as well reseal it, clean it up, paint it and put it back in and enjoy. Always start the car in park then shift it to neutral for about 15 to 20 seconds. This will refill the TC. I do it every time with my car. It's a habit of mine now. Let us know how ya make out with it.

Thanks everyone.

I have the new seals on order so I plan to reseal the pump.

Thanks for the tip about shifting into neutral first.

Rookie mistake for me was ia changed the fluid and checked it in park so I have been running it a bit low.

 

[66SportFury]

No problem. I learned that neutral trick from a good friend (MOPAR nut) of mine a long time ago. Ever since I started doing that I don't have any issues with it going into gear right away. Especially when my car sits for a long period of time. I also have a loose converter.