727 convertor drainback problem

[flyingfarley]

I have a 62 727 push button trans that the convertor drains back into the trans when the car sits, then it leaks out of the trans where the shift cable goes in the transmission due to the high fluid level. My question is what normally keeps the convertor from draining back to the pan.
The trans was just rebuilt, I got it used so i don't know if it did that before the overhaul. It also was converted to a 24 spline input shaft before I got it, but i doubt that has anything to do with the drainback.

Thanks in advance for the help...
Flyingfarley

 

[khryslerkid]

I wouldn't think that where the shift cable goes in, should leak no matter how over full the trans would be. The newer trans suppose to have a valve that holds the fluid in the converter. In the valve body maybe? My '03 Dodge Ram has that problem but the fluid comes up the dip stick tube. I leave it a half quart low and don't have the problem.

 

[1948 santa]

Clean the area well with lacquer thinner and then make sure the leak isn't coming from the throttle pressure shaft seal.

 

[idrivemopar]

I seem to have this drain back problem as well, my 727 is out of a 69 car, and when it sits, I have to run it in neutral before shifting into any gear, and also have some leak problems as well. Would be nice to know what is causing this to drain back. Mine is also a fresh rebuild.

 

[mopar 3 B]

Dirty or damaged torque converter control valve in the valve body will allow internal fluid leakage form the convertor.

 

[dvw]

They all drain back. No big deal start it up, let it idle in neutral (not park) 20-30 seconds . As far as leaks it shouldn't leak. Clean the area with brakleen and blow dry with compressed air. Dust baby power on the area and watch where it gets damp first. That will be your leak point. Shift cable has an O-ring. The cables themselves leak at the crimp (this can be repaired). Kick down lever seal is just above. Neutral safety switch is also close. All can be repaired in the car.
Doug

 

[idrivemopar]

Thanks Doug, my transmission guy said they all drain back as well. My leak is on the pan, not a surprise, but when I do my 500 mile checkup and filter change, I will seal the pan myself so hopefully it does not leak again. I got the speedo cable leak fixed by doubling the rubber bushing on the speedometer gear inside the housing.

 

[dvw]

Thanks Doug, my transmission guy said they all drain back as well. My leak is on the pan, not a surprise, but when I do my 500 mile checkup and filter change, I will seal the pan myself so hopefully it does not leak again. I got the speedo cable leak fixed by doubling the rubber bushing on the speedometer gear inside the housing.

Before condemning the pan make sure you look at the band anchor pin, and rear park housing using the above mentioned leak detection method. The anchor pin bore can be filled with RTV and a putty knife if it is leaking. The park cable housings are often warped and can be sanded flat on a piece of glass with sandpaper laid on it.
Doug

 

[Moparsmitty]

Another place you might want to look at for leaks in these old pushbutton TFs is the neutral safety switch. They have an external O ring seal under a cone washer that get leaky if they have been overtightened. Also, the switch itself can leak around the plastic insulator. These switches are rare and expensive but I have successfully sealed them using JB Weld. Good luck.

 

[Coronet 14]

The 904 in my 72 Dodge Coronet does the samething if it's been sitting for more than a few hours

 

[1970GTX]

Ya they all do it. I've had many Chrysler Automatics and they all did it. Like Doug says, just let 'em idle in neutral.

 

[dvw]

Another place you might want to look at for leaks in these old pushbutton TFs is the neutral safety switch. They have an external O ring seal under a cone washer that get leaky if they have been overtightened. Also, the switch itself can leak around the plastic insulator. These switches are rare and expensive but I have successfully sealed them using JB Weld. Good luck.

Good call I forgot the switch. I have modified the rooster comb to work with the late 3 pin switch. Not hard to do.
Doug

 

[YY1]

They do not ALL do it the same.

My 5th ave parts car engine does it in hours.

My 73 takes months.

Obviously the 5th Ave has a problem.

 

[al_wildman]

I am still not clear on how to disconnect the shift cable internally so the O-ring can be replaced. Can somebody please go over that? I've looked at all the manuals, pictures, etc. Also, if I don't turn the adjusting wheel during this process, then I don't have to worry about re-adjusting it, correct?

Thanks

 

[dvw]

I am still not clear on how to disconnect the shift cable internally so the O-ring can be replaced. Can somebody please go over that? I've looked at all the manuals, pictures, etc. Also, if I don't turn the adjusting wheel during this process, then I don't have to worry about re-adjusting it, correct?

Thanks

Easiest way is to remove the lock bolt. Count the number of turns ( or holes ) that the adjuster needs to turn to remove it from the cable. Then pull out on the cable. Using a small pick slide it between the cable housing and the hole in the transmission. There will be a wire clip about 1.5" into the hole. Push it away from the cable towards the side of the hole. The cable will pull out. If you can't get it remove the pan. It will be easy to see. Don't move the clip where it is easy to get at from below the pan. Use the above mentioned technique to remove it (while being able to see the clip) so next time you remove it the pan can stay on.
Doug

 

[monaco66coupe]

My cars would leak, so I bought the newer gasket that is really thick. You need longer bolts, but it works!

Pans warp over the years, so they don't seal well.

 

[Meep-Meep]

This is an annoying problem and would love to find a solution. Perhaps mopar 3 b has the answer. All I can say is my 69 GTS seems fine for the most part but my green Belvedere is terrible. Agreed they are not all the same so something is wrong. Hmmm, a guaranteed fix would be to install a 4 spd.