49 Dynaflow, leaking problems

[Guest j49plymouth]

I have a 49 Roadmaster, Dynaflow trans that leaks like a sieve. I just replaced the rear output shaft seal and the accumulator gaskets, car ran fine, no leaks, car sat for a month or so and now has oil all over it and a huge puddle on garage floor. This the first generation Dynaflow and was wondering if this is a common problem with them? it has been resealed twice.:mad:

[Guest shadetree77]

Have you replaced the front oil pump seal? If not I would try that next. I replaced mine last year along with an upgraded style of torque ball seal, a new propeller shaft seal and spring, and a new pump cover seal. It hasn't leaked a drop since. Now lemme' go find some wood to knock on.

[Guest j49plymouth]

replaced torque converter case seals, front pump seals, front pump gasket, accumulator gaskets and seals, torque ball assembly and prop shaft seals, springs etc. the next step is to completely rebuild the whole damn thing. I dislike the early GM and Ford torque tube design with a passion. It is a tossup between front wheel drive and torque tubes as to which I dislike the most. I refuse to work on the newer cars, and quit the auto dealers and went to fork lift trucks and heavy equipment before retirement.

[Pete Phillips]

What about the pan gasket?

My suggestion is to take a rag and wipe the transmission case dry, let it sit for a day, then crawl under and see where the leak is coming from. Yes, it can be frustrating. That sitting for a month or so is when mine start to leak. You can try adding a can of B-12 ChemTool to the transmission fluid; drive the car, and the ChemTool will soften the seals, allowing them to swell up and seal better. Don't worry about over-filling the transmission. The ChemTool will evaporate after it gets hot. To be certain that you get good coverage, I sometimes jack up the rear end and run the car in gear for a few minutes. This gets the fluid and ChemTool up to the front of the transmission. Then, jack up the front and do the same. This gets it to the rear of the transmission. You can't run it in gear with the front jacked up, but you can run it in neutral, and you can at least run it and put it in Drive and Low and Reverse, with your foot on the brake. I would do this before taking the transmission out of the car again, because that is such a pain to do.

Pete Phillips, BCA #7338

(4 Dynaflow cars: 1948, 1949, 1950, 1959)

[DonMicheletti]

I'm not sure about your torque converter. but some of the early ones had just a "paper" gasket to seal them. If the gasket failed the torque converter would puke oil like heck. Leter torque converters had an O ring seal. I would machine an O ring grove in the old style converter to cure the problem.

I agree with you on the the torque tube cars, they are a PITA. However, that hasnt stopped me with playing with old Buicks since 1960

[old-tank]

It is not uncommon (after prolonged disuse) for a dynaflow torque converter to drain back into the pan, overfilling it and as noted can leak from the pan or even the speedometer gear. If it doesn't leak then it can blow fluid out the filler when started. Drive it daily for a week and report back.

[Wheelnut]

Mine's leaking profusely too, but only when being driven. At the end of a few miles it will be covered in tranny fluid front to back and dripping everywhere.

[Paul Zitzer]

changed the dynaflow oil pan gasket twice resulting  a 2 week dry transmission.

after 2 weeks it was all wet again around the nuts and bolts holding up the oil pan. 49 Roadmaster Sedanet.

drives me crazy. Same problem with my 56 roadmaster.

is there a special pan gasket?

 

[NailheadBob]

I would check the flatness of the transmission oil pan where the bolts attach, if at some point over tightened and then when installed pan does not sit flat with transmission case, once oil pan removed the use a block of wood to fit in cavity where oil pan bolts are and use an hammer to flatten it back in shape, and also look for imperfections/cracks in oil pan and aluminum case of transmission.

 

Bob

[old-tank]

Make your own gasket using 1/8 inch sheet of cork rubber.  It'll take about 5 minutes to lay out a sheet of cardboard then the sheet of gasket material, put the pan upside down on it drill some 5/16 holes cut around it with a utility knife.  Put in a few bolts to hold it in plce and cut out the inside.  Glue your new gasket to the pan using weatherstrip cement.  Run a bead of RTV along the inside edge of the gasket.  Spread some RTV on the surface of the gasket and when almost dry install it.

I use the same technique on engine pans, valley covers, rocker covers and differential covers.

[EmTee]

Are any of the bolt holes open to the oil sump?  If so, oil may be leaking past the threads.  If that's the case, try sealing the threads (probably requires draining the trans to clean the threads in the casting first).