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Early Hydramatic Fluid leaks

Started by 4860S, March 17, 2013, 08:22:03 PM

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4860S

Hi everyone.

I have a 1948 60S with, of course, Hydramatic transmission. The fluid has been changed and after 18 months remains pink and fresh. I have two questions I'm hoping you might be able to help me with:

1. The tranny engages all four gears and there is no apparent slip. If I jab the throttle the kickdown also works. What I'm not sure about is how jerky the down changes should be. The worst is the change into 1st as it comes to a stop. This change is quite jerky, as is the up change from 1st to 2nd, although not as bad. Is this roughly normal for this box?

2. It leaks fluid, quite a lot, if left for a week or more, however, I may have overfilled it in the past through not having it properly warmed up before checking it. Yesterday I drove the car for over an hour, and checked it when I got home, it was full, leading me to conclude that I previously overfilled it. Should I be concerned about the leak?

Sorry for the questions, however, here in Australia, there aren't many people familiar with these transmissions and I don't want to go looking for trouble unnecessarily.

Thanks for your help.

Regards

curly

I find that my transmission has a rough 1-2 and 2-1 shift when cold and on the choke fast idle. Once the idle speed drops to the normal warm setting, the roughness goes away.  Perhaps your idle speed setting is too high?

Where does your trans leak from? Mine will do the same thing if left for a few days. It seems to be leaking from the extension housing area on the right. I am thinking that perhaps the Torque convertor is draining down after sitting for a few days.  I don't know, still trying it figure it out.

T Lewis

Richardonly

Helloooooooo John,

The way my 48 responds is on upward shifting, I tend to get a bit of a bang from 2nd to third, but is less depending on how I drive it.  Had the timing put on the mark and it immediately cut this bang in 1/2.  Still there, but I have NOT changed the fluid and am a bit afraid to do so.

On downshifting, it is smooth as silk, except if I accelerate quickly and should have to come to an abrupt halt, it will bang when downshifting.

Try checking your timing and also your vaccuum lines and distributor advance.

Hope all is well with you, Richard
1948 Cadillac Fleetwood 60S
1995 Lincoln Towncar, Signature Series
1995 Jaguar XJ6
2001 Chrysler Sebring Convertible
1986 Yamaha 700 Maxim X motorcycle

4860S

Hi Richard, hope all is well with you.

Thanks guys for your thoughts. I'm really trying to understand how much jerkiness is normal and the leaking back past the seal into the torque converter.

As I said, otherwise it appears the box is working well.

Regards

LeRoy DeVol

John, I was a automatic transmission mechanic in the 50's when these transmissions were common. The thing i did to fix the problems you described was to install 1 pint of lacquer thinner in the transmission, drive the car 100 miles, drain the fluid from the converter & the transmission, & refill with Dextron 111 fluid if you can find it. It takes 11 quarts. The thinner will clean the valve body, governor, & soften the seals. I found this to work most of the time. If you decide to try this let me know the results.
I own a 1947 Cadillac & had this problem about 5 years ago & after doing this the transmission has been working like new for the last 25,000 miles.

Lee DeVol 

R Sotardi #11719

Jon, A bit of rough shifting in a Hydromatic, especially an early one up to 1950, is not abnormal. That was the usual complaint from owners. I have two of 'em one a single range with the mechanical reverse ( like the 48) and a dual range 53. They tend to upshift quickly from 1 to 2 and 2to 3 is also and a slight bit longer due to the low range to high range change. On the down shift there is a slight lurch when dropping back to first. It can be disconcerning in L  when going from 1st to 2nd in the early ones. Remember, to come to a complete stop before placing it in R. The 51 and on were not mechanical like the 50s and before. I would monitor the leak, however. Neither of mine leak anything. Ron

Doug Houston

First, if the shaft seals in both the torus and the U-joint slip joint are OK, the transmission will not leak. I rebuillt the four Hydra-Maatics in my four cars (3 Cadillacs and Olds), and they simply do not leak.

Now, on hard downshifts, and a jerky 2-3 upshift, take out the valve body. It's inside the side cover, and not too bad to get to. Clean the valve bores, and the valves with either carburetor cleaner or Brakleen; both in squirt cans. The valve plugs should all pass through their bores easily by gravity. Once that's done and the transmission is back together, those transmissions shift firmly, but smooth as silk.

The other thing that could be a big help. is to check the external band adjustments. This procedure is covered in the car's shop manual.
38-6019S
38-9039
39-9057B
41-6227D
41-6019SF
41-6229D
41-6267D
56-6267
70-DeV Conv
41-Chev 41-1167
41 Olds 41-3929