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1956 Jetaway will not engage

Started by Bronze, October 23, 2021, 03:39:49 PM

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Bronze

I am in the process of getting an old 4 door sedan on the road again. Tore down the engine. Rings, valves, carb and all the usual and now she purrs nicely. Had to change a rear axle shaft as one was shot.  Changed trans fluid , crossed my finger and put her into gear....of course nothing happened. Or well, initially i thought nothing happened. In idle it does not matter what position i put the gear selector in, it does not engage, rpm does not drop. But, if i rev it to about 1500rpm it will start creeping backwards, regardless of what position i choose, Dr 1, Dr2, Lo, n or Rev. it will move backwards when revving.
I know the normal (and sensible) answer would be "looks like you need your transmission rebuilt" but i want to explore any cheaper options first. Before i rip out the trans i will drop the pan, check what kind of sludge is in there check the oil screen and clean everything up.
Car has not been running for at least 25 years.
Could the condition i have described be attributed to a clogged and dirty valve body?
How hard is it to take out the valve body and clean it up?
Any tips and opinions would be appreciated. (especially from mr Zimmerman who seems to know these trannys inside out  :) )

TJ Hopland

Was it working reasonably well recently or have you never actually seen it work?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Lexi

Same thing happened to my 1956 CDV when I brought her back to life in 1976. After a successful start up, (she had sat idle for a couple of years), there was nothing when put in gear, any gear. Zippo. No change in engine RPMs either. The owner of a local transmission shop and who had also worked on the line making Hydramatics in the mid '50s, diagnosed my problem as a shot control valve, as he called it. The piece that looks a bit like a "brain" in the transmission casing. He couldn't fix it and I had to find a donor transmission for this part. If that is your problem I am not aware of quick, cheap fix. Clay/Lexi

Bronze

Thanks for the input, Clay. That is actually kind of good news. I think your control valve or "brain" equals the valve body. And i much prefer to service that or swap it rather than taking out the whole transmission.

Roger Zimmermann

The valve body is not that difficult to remove. It's an easy job when the transmission is on its beck, but on the car, with transmission oil dripping, it may be less fun! There are 7 or 8 small bolts attaching the valve body to the case, a 7/16 wrench is needed.
Before you begin to remove the valve body, check if the pin from the sector is engaged into the manual valve; that could be the reason why you have no gear. Have a look at the attached pictures.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

Lexi

If you have the shop manual, Section 12 covers the transmission and there is a segment on the control valve. There was also a "Hydra-Matic Transmission Service Manual", (Paul Marsh Company, Detroit, Michigan, 1956, # HM 1001). Details Hydra-Matics 1949 - 1956. There is a section in that manual that addresses the "Disassembly, Cleaning, Inspection, Repair, Assembly and Installation of Control Valve Assembly". Lots of pictures and laid out to train mechanics who have never had any Hydra-Matic training or experience. Even I understood this well laid out section. Clay/Lexi

Bronze

Thank you so much for replies and pictures. Automatic transmissions are somewhat a black art to me. I do have the shop manual with all the pages describing the functionality, and those pages are to me as tempting to read as doing my tax return....
But with your advice I will check what can be checked and then if needed pull the valve body. Will there be any springs or checkballs flying around at that point or does that come later when taking the body apart?
/Martin

Roger Zimmermann

Nothing should fly when you are removing the valve body assembly. However, when taking it apart, there are 2 balls on '56 models, one large and a small one. Be careful with that! I'm suggesting that you take apart first the manual valve body, fig. 12-96 from the manual; you may find some issue. Don't mix the springs!
If you go further with the disassembly from the other valve bodies. don't be afraid if some springs are missing compared to the description found in the manual. There were changes after publication of the manual.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

Bronze

Well, took the pan off today. And it was a mess! a thick layer of hard gunk in the bottom and the oil screen completely covered in the same gunk. The pin from he sector is in the correct place, but i guess that if the oil screen is completely congested there would be no pressure and nothing would happen. The small movement i had could just be from the way the valves were sitting and a very small amount of oil getting through. I will clean everything up put new o-rings on the pick-up tubes and a new pan gasket and see what happens.
One thing i don't get is that the hole in the oil screen where the longer tube enters is quite a bit bigger than the tube itself. seems to me that quite a bit of oil could get in that way even if the screen is clogged up? or even if the screen is clean and fine there seems to be a by-pass that way where "unfiltered oil can get past?

Roger Zimmermann

Yes, there is some free play. Probably not enough to build up pressure. It would have been interesting to check what there was for a pressure. There is a small bolt at the bottom of the rear pump body for that purpose. Of course, you need the pressure gauge...
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

Bronze

Hi Again,
Here is an update:
Cleaned the oil screen and pan. checked that the sector pin is correctly engaged. I thought it was so dirty it was worth putting it together with a new gasket and o-rings for the pick up tubes and test.
It does the same thing it wants to move backwards, a little bit more strongly now with the clean oil screen, but still slipping. It does not matter what position i put the selector in, no change in sound or behavior. However there are no noise from the transmission. There were no bog hard chunks in the mess i cleaned out, just old grimy oil.
I have a feeling that the same gunk is in the valve body and all or most valves are locked up by this. Does that sound like a possibility to you who understand an automatic trans better than I do? I.E. would it be worthwhile taking the pan down again and clean the valve body or should i just give up and take out the transmission?

The was a band visible and it was very loose, i could move it about 10mm back and forth. Should it be that loose?

Thanks for your wisdom...
/Martin

Roger Zimmermann

Yes, the band is loose.
The shop manual is giving some possibilities for a situation like you have; for example a slipping front sprag clutch, or the rear one which is slipping, no neutral clutch apply (due to a dirty valve body?). Hard to tell from here...
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

Bronze

Hi Roger,
Thanks for your reply as always.
I was thinking that if it was the clutches, i should notice some change in behavior as i move between the gear selections. As absolutely nothing changes, it t feels like the oil flow in the valve body remains exactly the same all the time. As if the car was left standing in Reverse for 20 years and the valves are stuck in that position. I was looking in the shop manual and the closest condition it describes as far as i can see is "Reverse when in N" but that does not account for my condition "Reverse in all positions" Maybe the guys who wrote the manual did not calculate on a car left for an infinity with extremely dirty oil in the tranny  :o

dn010

I am sure you're absolutely tired of draining the fluid and removing the pan, but in a last ditch effort, I would try cleaning the valve body. I would have no doubt that something is stuck in there. Are you letting the transmission fluid get hot?
-----Dan Benedek
'57 Cadillac Sedan Deville 6239DX
'81 DMC DeLorean

Bronze

Thanks for your reply Dan,
Yeah it is getting a bit tedious, but on the other hand now it is cleaned up no bolts are stuck and it gets easier second and third time around. I don't think the fluid has gotten up to working temperature as i am afraid i may wear hard on the trans when it is slightly engaged in reverse all the time. I mean even in park, the car moves an inch backwards and brings down the idle rpm a bit. Do i dare to keep the engine running that way for say 10 minutes? i guess you are suggesting the Hot fluid might have a better chance of freeing up something, right?

carguyblack

Maybe elevate the rear end while warming it up. I sure would hesitate running the transmission against itself in park until you get it figured out. I am watching this post with great interest but can't be any real help. I had mine rebuilt by an old time professional - knowing my limitations!
Chuck
Chuck Dykstra

1956 Sedan DeVille
1956 Coupe DeVille (2 sold)
1957 Oldsmobile 98 (sold)
1989 Bonneville SSE

Bronze

Hi Chuck!
You beat me to it! I just realized that i should put it on jack stands and let it work for some time. Will do that and report back. On the other hands, if it works we won't get to know how the valve body looks inside....

Bronze

Ok, quick update:
I put the rear end on jack stands today as Chuck suggested and let the wheels spin. strangely i did not spin at all in fwd, but spun backwards in R and N.
Now with less fear of damaging the transmission i let it spin for 20-25 minutes and get warm. turned it off and let it cool and tried again. First change was that i could hear something change when i went from R to L, that familiar "clunk" and a small shudder in the car when the trans engages. Before there was no reaction at all when shifting the gear selector. Third time i tried it, the wheels spun forward in Dr and Lo and backwards in R. Progress! took it down from the jack stands and strangely it went back to its old behavior it still wants to reverse in all gears when it is under load. I can't find a logical explanation for the behavior, but it certainly feels like giving it some exercise on the jack stand is freeing things up little by little. I will continue the same thing tomorrow. The good thing is that there are no strange noises and no burnt smell. The oil is still nice and pink so not too much old carbon build up getting loose either. Tomorrow my neighbours can continue to watch me sitting like a moron in my old black Cad, one foot on the accelerator, hand on gear selector head hangin' out watching if the rear wheel spin forward or backwards.....
EVening here now, time for a glass of red wine, right Chuck?

Bronze

Correction, I misrembered, Back on the ground, it now wants to pull backwards in R and N. In Dr an Lo it acts like in neutral, no pull in either direction. I guess the forward rotation on stands was so weak it isn't perceptible on ground.

carguyblack

You're a funny man, Martin! Perhaps something a little stronger than wine would be in order. Hey, who cares how silly it might appear - you are doing it for a great reason!
I'm sure you're trying to avoid the valve body rebuild but it sure seems to be pointing to that. I
Chuck Dykstra

1956 Sedan DeVille
1956 Coupe DeVille (2 sold)
1957 Oldsmobile 98 (sold)
1989 Bonneville SSE