National Desoto Club

We have got a 1956 Desoto Firedome with powerflite transmission. When the transmission is cold (cold start), the transmission does not shift. Depending on the weather it takes 10-15 minutes before it finally changes gear. We use Dextron 2 oil. The only thing I can do to drive safely is putting the gear into D while braking for 10-15 minutes. Who can help us?

Ina Meulman
The Netherlands

So why do you put your foot on the brake? The good news is that you can drive up to 60 MPH (100 KPH!!) in low gear.

I am standing still for 10-15 minutes because I cannot drive fast enough when the transmission does not change gear. To warm up the transmission faster I put the gear into D and press the brakes.
With a cold engine I daren't drive 60 MPH, the engine makes a lot of noise then when pressing the gas throttle (high RPM). I doubt that I can drive 60 MPH when the engine is cold...

Ina, I am NOT a transmission expert. However, I have a question for you. Once the car is warmed up and everything is working properly, if you THEN shut it off and wait 10 minutes and re-start it, does the transmission shift normally? It sounds to me like you have a bad front pump and it takes a long time to pull the fluid into the torque converter. If the torque converter is "still" full, like after a short stop with the car, it may work normally, but it if drains out and has to be re-filled like after a long stop (engine cold), that may be the issue.

I think what Steve is suggesting in his post was that the transmission only has 2 speeds anyway, so it should not be a problem to do limited driving in only the one gear. It may be better than revving the engine with your foot on the brake.

I would start by removing the pan and check the screen on the pickup tube and adjusting the bands.The front pump maybe going bad also

If it operates normally when warm, and it pulls well in low when cold, I'd suspect a sticking governor.

So does it pull strong when cold in low?? How about reverse?

If it does not pull strong when cold, I'd start checking pressures. If you are equipped to do this, I can send you the procedures.

Good Luck
Steve

Reverse works welll when cold. It drives in low when cold but I cannot drive fast then (high RPM).

....when you say you cannot drive "fast" what do you mean? Can you drive 30 or 40 MPH?? Or does it barely go?? BTW, there is no problem driving 40 MPH in low gear.

Steve

Is this a new problem? Have you had the car for awhile and it worked fine or did you just get it and are not real familiar with it?
I do not know about the 56 but my 53 requires you to let up on the gas for it to shift into the next gear. Is this required for a 56?

By saying that I cannot drive fast enough I mean I cannot drive more than - I think - 30 MPH for the first 10-15 minutes. Too dangerous for the highway and I think bad for the engine because it makes a lot of noise due to the high RPM.
That the oil pump is not functioning well sounds plausible to me. I thought it could be the oil (too cold) that is why I put the gear into D (to warm up the oil faster), but if ithe oil pump is the problem that may not help. RUnning the engine for 10-15 minutes will do then.

The problem occurs when the car has not run for hours.

We have some weddings to drive this summer but I think we will buy an rebuild kit for the transmission and rebuild the transmission in winter.

Are these good ones?

http://cgi.ebay.com/ebaymotors/53-54-55 ... _923wt_958

http://cgi.ebay.com/ebaymotors/POWERFLI ... 2643wt_958

We have got the 1956 De Soto service manual. Is there a good service manual for the Powerflite transmission?

Thank you for helping!!

No, it is not a new problem. I have had the car for two years now, it has never worked fine since then. Until now we never had the time to solve it and in Holland Desoto knowledge is hard to find.

I would appreciate that anyway.

Ina-I think you are saying your car will not shift into high gear or even second gear when the transmission is cold. Back in the 60s I had a similar problem with my very used high mile used 55 Buick Century-it took 5 minutes of idling on cold mornings before the transmission would go.
Have you checked the transmission fluid level on the dipstick when you first start the engine??? If the fluid level is low enough, you could have this problem.

It's very likely you have low pressures due to worn parts and might need to rebuild the transmission.
Martin Lum

...........dump a can of Sea Foam transmission cleaner down the tube and drive it around quite a bit. Then drain it while hot and clean the pan and the screen. While the pan is off, adjust the kickdown and reverse bands and clean the regulator valve. Then fill it back up with fresh clean Dexron 1, 2, or 3 and see what happens. Adjust the throttle, idle, and kickdown as per manual.

Report back

Steve

Ina,

Regarding a manual for the Powerflite transmission: The only separate manual for the Powerflite that I am familiar with was issued when the Powerflite was introduced in 1954. In following years - including 1956 - an extensive transmission section was added to the service manual.

Regarding a source for parts: I have not personally done business with these folks but they have been in business serving the old car hobby for many years. Must be doing something right:
http://www.desoto.org/index.php?name=PN ... c&start=15

Good luck with your DeSoto!

Mark