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1956 PowerFlite Troubleshooting: Not Going into Gear after Working Fine
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PolyJ
Posted 2022-02-16 2:07 PM (#619462)
Subject: 1956 PowerFlite Troubleshooting: Not Going into Gear after Working Fine



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Location: Denver, Colorado, USA

 

I'm hoping to get some help diagnosing and resolving an issue. This past weekend, I purchased a 1956 Dodge with a 270 and PowerFlite. The seller claimed the car was ready to drive around town. When I test drove it, the transmission functioned well in reverse and shifted nicely from low to high with no issues slipping or hesitating. After I got down the road about 1/4 mile out of town, I went wide-open throttle, and the transmission kicked down crisply and then upshifted smoothly as expected. Once I got up to 50 MPH, the engine started bogging down and popping through the exhaust, and I lost most power. I suspected a fueling issue since the car had been sitting for years likely with old fuel in it. To get back to the seller's home, I had to keep the throttle wide open, and the engine ran at about 1,000 RPM at 35 MPH the whole way back.

 

When I explained to the seller that the car was running poorly, he drove it around the block and returned. He convinced himself the transmission was slipping despite me explaining the engine RPM would be spiking if that were the case and not bogging down like it was. I went to pull the engine and transmission dipsticks to inspect/smell the fluids as I continued by inspection and noticed the transmission dipstick was missing. When I pointed that out, the seller jumped to the conclusion the transmission was low on fluid. Against my urging we use a wire to check the level, he dumped three quarts of Dexron III in and took the car out again. When he returned, fluid had overflowed out of the tube and had run down the entire right framerail. The seller said it was still acting up and poured in another two quarts against my warning that the transmission was overfilled. Fluid poured out of the tube, and he drove it around the block again. Upon returning, I got in the car to see what was happening with the transmission he was claiming was slipping, and it would not go into any gear. The slab the car was on was slightly sloped to where in neutral or at idle in any gear the car would roll back a little. In low, high, or reverse, the car would roll back at idle, and revving up to approx. 2K - 3K rpm the transmission would grip enough to hold the car in place. This happened in reverse as well. I suspected that the seller foamed up the fluid by overfilling and driving it since all gears began malfunctioning at once.

 

I ended up purchasing the car. When I got it home and off the trailer, I drained the pan through the dipstick tube hole and put in 3 quarts of fresh fluid after reading that the pan holds around 3.5 quarts. The fluid I took out looked clean, not overly dark, had no sludge, and did not smell burnt. The transmission still wouldn't go into any gear. I adjusted the shifter cable per the factory manual and verified that it and the push-buttons were functioning properly at the dash console, but the transmission still wouldn't go into gear. I pulled the transmission regulator valve and found that it looked clean, free of damage/wear, and the inner passage was clear. The spring was fine. I pulled the converter regulator valve and confirmed it was clean and free of damage/wear. The spring was fine, but I noticed when removing/installing the plug that the spring did not give preload like the transmission regulator valve; I'm not sure if it is supposed to or not.

 

After all this work, I was able to get the car to start slipping into reverse by revving the engine way up, and it eventually went completely into reverse for about 30 feet before slipping out of gear. I was able to do the same thing to get it into low for about 15 feet before it slipped out. Then it wouldn't go into any gear same as I describe above at the seller's house. I added a pint of fluid to bring the pan to 3.5 quarts total but saw no change in operation. The fact I was able to get it into reverse and low and that it was operating just fine when I first test drove it leads me to believe there is either a pressure issue or an issue with the shifter mechanism in the transmission. The fluid looked good to where I doubt the screen is clogged, but pulling the pan will tell me and also let me inspect the shifter mechanism while operating the push-buttons. I haven’t pulled the pan yet.

 

I don't have the proper fittings and gauges that go high enough to check the operating pressures and really don't want to buy them. I will be pulling the engine and transmission to replace with rebuilt units I'm working on, but we wanted to be able to cruise around in the car while rebuilding the other engine/transmission.

 

Does anyone with experience have diagnostic suggestions that I haven't already covered?

 

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Shep
Posted 2022-02-16 7:09 PM (#619475 - in reply to #619462)
Subject: Re: 1956 PowerFlite Troubleshooting: Not Going into Gear after Working Fine



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You need to get a proper dipstick and check the actual fluid level first. That trans holds about 11.5 quarts from empty. Overfilling will, as mentioned, will foam up the fluid, given enough time operating it like that can cause internal damage. Can't see it not moving in any gear though. These units are pretty tough in general. Overfilling seems to be the turning point that brought about the issue.
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PolyJ
Posted 2022-02-16 8:56 PM (#619477 - in reply to #619475)
Subject: Re: 1956 PowerFlite Troubleshooting: Not Going into Gear after Working Fine



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Location: Denver, Colorado, USA

Shep - 2022-02-16 5:09 PM You need to get a proper dipstick and check the actual fluid level first. That trans holds about 11.5 quarts from empty. Overfilling will, as mentioned, will foam up the fluid, given enough time operating it like that can cause internal damage. Can't see it not moving in any gear though. These units are pretty tough in general. Overfilling seems to be the turning point that brought about the issue.

My 1956 manual shows 10 quarts for the converter and pan, not 11.5? With the transmission coming out eventually, I don't want to invest in finding a dipstick for a PowerFlite. Can you give me the length of the dipstick (not including the handle) and the measurement from the tip of the stick to the full line? I' can make up a piece of tie-wire as a dipstick if I have those measurements.

The engine ran for probably a total of 10 minutes overfilled, so I'll be surprised if it hurt anything. I'm more worried that when the seller was driving it after convincing himself the transmission was slipping that he might have tried revving up the engine and jamming it in gear or something. I've read of people having pressure issues after the pump/converter tangs sheered off, but that wouldn't explain how I could get it into reverse and low after revving high.

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Shep
Posted 2022-02-17 8:02 AM (#619488 - in reply to #619477)
Subject: Re: 1956 PowerFlite Troubleshooting: Not Going into Gear after Working Fine



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I no longer have the 55, but I personally rebuilt that trans and it needed 11.5 qts to fill it. At this point a pressure test may be in order once the fluid level issue is resolved, this will eliminate unnecessary guesswork. It is possible the screen is partially blocked with sediment. All guesswork at this point. My car may have held more because of a larger convertor and the cooler plumbing.

Edited by Shep 2022-02-17 1:25 PM
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Powerflite
Posted 2022-02-17 11:41 AM (#619492 - in reply to #619462)
Subject: Re: 1956 PowerFlite Troubleshooting: Not Going into Gear after Working Fine



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I measured one of my powerflite dipsticks and found 15-1/16" to the end, and 1/32" shy of 13" to the full mark. This is relative to where the top of the tube would make contact with it.
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wizard
Posted 2022-02-17 12:23 PM (#619494 - in reply to #619462)
Subject: Re: 1956 PowerFlite Troubleshooting: Not Going into Gear after Working Fine



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To me it seems like internal leaks.
You could try a seal saver like Omega 917, but that might help or not.
Naturally correct fluid level is very important.
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PolyJ
Posted 2022-02-17 5:56 PM (#619504 - in reply to #619492)
Subject: Re: 1956 PowerFlite Troubleshooting: Not Going into Gear after Working Fine



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Posts: 143
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Location: Denver, Colorado, USA

Powerflite - 2022-02-17 9:41 AM I measured one of my powerflite dipsticks and found 15-1/16" to the end, and 1/32" shy of 13" to the full mark. This is relative to where the top of the tube would make contact with it.

 

Thanks for the measurements; I was able to make a dipstick out of some 12-gauge solid copper wire I had lying around. For what it's worth, the pan holds 4 quarts hot, so my start of 3.5 quarts was in range.

 

It looks like I sorted the issue. I pulled the pan and found the strainer was largely clogged with a type of fiber, almost like paper pulp as if someone tried to clean it with a paper towel. Interestingly, the pan had extremely little sediment in it, and the transmission internals look spotless. The shifter mechanism and kickdown work smoothly. After sonic solvent cleaning and blowing off/out the strainer, the transmission functions properly. While I don't know what the fibrous material was, I assume that the seller overfilling the transmission so much and driving it might have knocked enough debris loose to clog the strainer enough to cavitate the pump. I'm glad it wasn't run in gear long enough to hurt the frictions.

 

Now onto going through the carburetor and fuel system to resolve the fueling issue.

 

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Shep
Posted 2022-02-17 6:37 PM (#619508 - in reply to #619504)
Subject: Re: 1956 PowerFlite Troubleshooting: Not Going into Gear after Working Fine



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Location: Chestertown, NY ( near Lake George)
Thought so, fibrous material is usually clutch material. You may have to clean that up again after some drive time. Big relief not to have to pull it, which is tough without a lift. You should adjust both bands also.
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