Well, what have you tried so far?

 

like said before, mine was just barely registering on the very bottom of the dipstick warmed up and running.and it was still slowly dripping out.i figured this would have been a problem ran across by all the big tranny guys on here...

 

are you running a deep trans pan or a stocker?

 

stocker..

 

Same issue with a B&M Deep Pan

 

i just found out that it can possibly be coming from a leaking plug on the pump that is right by the vent tube...definitely a good possibility in my case because i did disassemble the pump for inspection and might have overlooked it..

 

Ok guys… I just joined this forum to answer this question. I currently have the 700r4 trans out of my 80 Malibu for the same issue. Here is what is happening:
The input drum rotates and the fluid climbs the surface and is being flung into the vent passage in the pump. From there it is a gravity leak down the side of the trans.

History:

GM had this issue in 1991 and they had to install a trans into a truck with the floor pans cut out and holes in the trans case, with little plexi glass windows and cameras to film what was happening. GM trucks were burning to the ground because the fluid would run onto the Cat converter and catch fire! Good ol General Malfunction!

The Engineer found from the film that fluid was climbing the input drum.

My builder used to work for Hydromatic at the Milford proving grounds and this info came from him…..I live in Michigan….

The fix:

Attach a piece fuel line or = and run up to the level of the dip stick fill tube. The fluid will bubble up and then run back down. Or you can install an elbow in the fill tube and make it re-circulate the fluid. No need then for a reservoir at the race track!

I removed the cheap plastic tube…and pressed a 6mm brake line into it and attached a hose. You already have the metal tube ……. General Malfunction did not cheap out on the newer transmissions….like they usually do!

I was just surfing and found this post.

 

all i can say is wow..the only question i have is how did the factory fix this problem and why would it do it only after my rebuild?nothing was altered but billet servos,better clutches, and 3-4th litle spring deals that the rebuild manual says to remove for better shift quality under 5,800 rpm or something similar. but i love the info man thanks alot and welcome to the site.

 

The GM fix was adding the rubber hose up to the level of the fill tube.

Also from my builder:

The trans in your car and mine was not designed to be spun up past 5,600 rpm.
If you do (and I do) spin past that it WILL force fluid up thru the vent. I opted for the elbow re-circulate idea.

The level of fluid to air is called the split line. My first attempt was to add a deep pan and lower the split line. It did not work. Still spit fluid out.

If you look at 4WD GM trans 700r4 and 4l60 they have a vent tube that Y’s from the T case and trans up to the fill tube.

My trans has most of the same mods as yours but with 5 pinion planets….nothing that you thinks will cause an issue.

 

Also forgot one other thing. The oil pump. If you split the pump you will find the worm paths to direct the fluid. If BOTH surfaces are not dead nuts perfect….it could cause some cross pressure bleed into the vent passage too. Most rebuilders will replace the pump with a re-maned or re-surface it to make sure.

 

wow thats a crazy factory fix. i havent seen on ewith a t. but yeah i had opened mine for inspection so thats probally the cause in my case. but oh well..i had teed the vent tube and got it going into the dipstick tube ..quick fix ....

 

Would this still be a cause if your transmission doesn't see 5600 RPM's?

 

Im having a simular prob with my 4l60e that has been rebuilt. It only leaks when the car is driving down the road. I put it up on jacks and ran it and no leak. I even put it in 1st gear and let it spin and nothing. It also dont seem to leak on very short trips. Does this sound like the same problem?

 

Definitely..but be sure to make sure it isnt coming from the dipstick grommet..those will leak if the dipstick tube is just a little bent and focing a small gap in between the tube and grommet.

 

I have a 1995 Chevy Suburban with a 4L80E transmission and it seems to be leaking from the overflow tube. It is a 1994-1995 model. Is this new enough to have already been fixed by GM and I need to look else where for the leak? Should I extend the overflow tube.

 

I rebuilt 4l60e (first tranny). Fluid from vent tube. Blew cooler lines out, not plugged. Disconnected cooler line to triple check that pump is working. It is. TQ installed with proper clearance. Dipstick says fluid correct level. To eliminate false reading. Dropped tranny fluid and installed only 4 quarts and it started kicking fluid from vent tube. So my question is: From what I have read it has to be pump. I originnally opened pump up and it looked fine. So what in the pump could be wrong. Or is it something else. I live in Minnesota its warmed up to 30. But doing this in my muddy driveway with a stubby bottle jack. On weekends. Any help is appreciated. I've already cone to the conclusion, tranny coming out again......

 

I would check level of fluid.
Too much or maybe overheating making it puke out the vent?

 

​​​​​​​i was hoping that was the answer. But dipstick says its low. Plus I went and dropped fluid to check pan for debris. Clean pan. Added new fluid and got 3-4 quarts in and it started again. I'm stumped. Not sure what to look for. Plan is to tear it all apart and put it all back together

 

Did you install the correct pump gasket?

 

​​​​​​​I did pull pump apart to see how it works and if it was worn. I remember replacing the outer O ring and bushings. I'm not 100% positive that I replaced it but fairly confident. Was it the right one. Far as I understand it wouldn't affect much.