Trans fluid leak after making a run, and between trips to track

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Les Gibson

Les Gibson

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Good morning Mopar race gurus! I have yet another question for the sages who post here regularly.
Made my first trip of the season to New Oxford Dragway, and I noticed after each run I made some trans fluid leaking from the front bell housing area of the transmission. It was a fairly large puddle of about 3 inches in diameter after my first run and it stop dripping after a couple of minutes. With each run it was less of a drip after getting back to my trailer and shutting the car off. I looked under the car in my trailer yesterday and there was maybe a quarter size dot of trans fluid on the floor. Could this be the converter draining down after a run? Or an issue with the front seal? I will also say that it didn't leak a drop while my Dart was in the garage all winter, and I will also say that I neglected to check the fluid level before I went to the track.

Any thoughts?
 
If it's inside the bell it's front pump seal or.....a hairline crack on the front pump drive on the converter. I split 2 904 converters with nitrous back in my street racing days. The crack would open up with rpm. My experience.
 
Your transmission is over full.

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Remove the pan, and leave the stick in.

Run a straight edge across the pan surface. Mark the stick and make your final mark 1/4" - 3/8" inch below this.
 
Make double dang sure it's actually coming from the front. I chased a leak for days to find put it was the manual select seal(shift shaft). It would run down the front of the case and drip off the front like a pump seal. Hope you find it!
 
Did you block the original vent? So this was a running, no issues like this last year combo? If so, probably overfull a bit. Second on list, converter hub. The stock pump gears are a bit loose fitting and hammer on the snout. Crack the hub or break the tangs. A&A sells a pump gear set that should stop it, along with a quality snout/converter. Actually change the order, snout first unless you added or changed the fluid.
 
furrystump said:
Did you block the original vent? So this was a running, no issues like this last year combo? If so, probably overfull a bit. Second on list, converter hub. The stock pump gears are a bit loose fitting and hammer on the snout. Crack the hub or break the tangs. A&A sells a pump gear set that should stop it, along with a quality snout/converter. Actually change the order, snout first unless you added or changed the fluid.
Click to expand...
I'm running this 727TF as I received it after Lou Jasper in Colebrook, CT, installed a transbrake in it in the spring of 2020. He also went through the trans and made sure everything was good. Same with the converter, it was sent to Dynamic Converters and freshened up at the same time. I don't push the car hard, 3400 launch RPM and shifting at 6500. I've always had an issue with the converter draining down while the car sits and leaking some fluid out the front, both before and after Lou went through it. I'm leaning that it's just over full. I'm going to drain some out of it and see if that has any effect.
 
roccodart440 said:
Your transmission is over full.

=================================

Remove the pan, and leave the stick in.

Run a straight edge across the pan surface. Mark the stick and make your final mark 1/4" - 3/8" inch below this.
Click to expand...
You going to be running at LVD this weekend? I'm heading over from Maine on Thursday.
 
I will be there for the weekend, Friday rental also. The converter draining back shouldn’t make it leak in the bell area, if it doesn’t leak while running. It does raise the level and can make the dipstick tube leak/selector seal leak. The vent is under the metal or plastic cover at the 12:00 position on the pump. Transbrake seem to create the most vent leaks, no idea why. My 904 pump from A&A had the vent npt thread with a plug. Relocated mine, if the pump wasn’t already plugged, I would have left it alone.

3AEA680B-5B60-4A07-9027-22AAF4FFA1B2.jpeg
 
furrystump said:
I will be there for the weekend, Friday rental also. The converter draining back shouldn’t make it leak in the bell area, if it doesn’t leak while running. It does raise the level and can make the dipstick tube leak/selector seal leak. The vent is under the metal or plastic cover at the 12:00 position on the pump. Transbrake seem to create the most vent leaks, no idea why. My 904 pump from A&A had the vent npt thread with a plug. Relocated mine, if the pump wasn’t already plugged, I would have left it alone.

View attachment 1715931994
Click to expand...
No, I don't believe it leaks while running, as I see no evidence of any ATF anywhere. Just a little drip after a run, and when the car sits for a while. That's a good idea with the vent tube.
 
They have a couple of styles. The plate and the circle at the top of the pump.

706D74E9-A0FD-4A27-8E50-728ACBEE4197.png
 
Followup... trans was merely overfilled. Drained some fluid out and no more leaks. I appreciate everyone's input!
 
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