Fluid Drive stalling and leaks

[plymouthfury]

I have a 1941 Dodge with fluid drive that sat for many years. 
 

Engine runs excellent and car can be put into gear and engine doesn’t stall when letting clutch out. Fluid drive appears to function but when trying to move the car it doesn’t want to move and the engine seems to struggle and after about 20 feet the engine starts bogging down and eventually stalls unless you let off the gas. Basically the car is undrivable. 
 

I did discover that it appears the fluid drive coupling must be leaking severely. It leaves a nice trail and puddle and drips quite a bit out of the bellhousing while the car is running. 
 

Some insight on potential causes for the stalling and fixing the leak would be helpful before I delve into it.

 

I do have a 1939 Chrysler 6 with OD trans. Are the fluid drive components the same between the two?

Edited March 5, 2021 by plymouthfury
Typo

[MarcDeSoto]

You can't drive a car if the fluid drive is leaking.  First, you will have to find the source of the leak.  First check the fill hole.  If it's leaking there, you are lucky.  Tighten the nut and check again for leaks.  If it's somewhere else, you may need a fluid drive overhaul.  There is a shop somewhere in WA I think disscussed on one of these threads that offers complete fluid drive rebuilding where they open up the housing and install a new bearing.  I think Chrysler did not have the Fluid Drive until the 1941 model year and they didn't have overdrive.   

[plymouthfury]

Well obviously the leaking unit isn’t helping anything but will the low fluid level cause the engine to stall when trying to drive? Though reverse seems to function better. Was looking for some insight of what would cause a massive leak and parts availability before I start tearing stuff apart. I’ve had many fluid drive cars that never had any problems. This is the first one that let me down!

 

Chrysler did have overdrive and I have the engine and transmission out of one that was being turned into a “hot rod” by some other guy. Wondering if the coupling is the same as the 41 Dodge should I need parts. 

[busycoupe]

If the fluid drive is very low on fluid it will slip, not bog down the engine.  Since the car has sat for a number of years and bogs down the engine when you try to drive it, I suspect that the brakes are siezed up.  

[James_Douglas]

Jack the car up and disconnect the drive shaft at the transmission. Start the car and run the engine and put the trans in each gear and see of everything works fine. If not, then you know it is between the engine and the output shaft on the trans. If it works fine, then it is the brakes or the rear end.

 

Make sure the drum or band is not binding on the parking brake.

 

The fluid coupling as a graphite (carbon) seal. If it gets cracked, usually due to someone taking the trans in or out or the clutch in or out without immobilizing the coupling. I just wrote a response to someone else on that subject.

 

The company that will cut open the unit and replace the inner bearing and change the seal to a modern seal is North West Transmission. It is not cheap, like $1500.

 

They did a seal for me years ago and it leaked after about 30 months. That was a stick seal replacement. I may send them one to see their new process, but I want it fully documented with photos and they are resistant to do that. Like anyone is going to spend the money to build the jigs this would require.

 

My problem us that I paid then something like $800 with all the shipping and only got 30 months on a "rebuild".

 

Since then I have required all the tools necessary to replace the seals myself. The inner ball bearing however can only be got at by cutting it open and that takes a lot tooling that is not practical for a hobbyist unless one has a very big lathe. My 10 inch swing Logan lath is way too small to fit a fluid coupling.

 

Your best bet is to run down one or two fluid coupling from a junk yard as long as you can supervise the removal. If they pull it off without isolating the movement of the clutch you stand a 50-50 chance of a cracked seal.

 

If they have them out offer then $50 at most. If they will see at that price by 2 or 3 and swap them in until you hit a good one.

 

On the unit that I had NW Transmission do, I swapped one out from a 1950 Chrysler I found in a yard. We had to cut and move the ring gear forward or back and that was no big deal. I thought it would be a temporary solution. It has worked fine for 15 years...

 

James

[plymouthfury]

I figured if anything the engine would over rev with low fluid. The car has new brakes and easily rolls without any apparent dragging. Just got to dive into it and start troubleshooting.

 

Not looking forward to fixing the leak however. It’s leaking pretty badly so I’m assuming the worst.