Good Morning,

I have a 1947 Oldsmobile Series 68 with the Hydramatic transmission. While I was driving it this last weekend, it has started slipping while changing gears. Fluid was low (I added a qt) and the fluid is very dirty. After topping it off I went to drive it again and it's doing the same thing. Slipping while changing gears. Question I have is this. Is it worth the time to change the fluid? I haven't owned this car all that long and don't know when it's been done in the past. or should i just go ahead and get it rebuilt? being that its slipping through every gear shift I'm not sure if changing the fluid will do much. Any help/opinion/advise would be very much appreciated.

Thank You

 

Changing the fluid is fairly inexpensive and, in my opinion, would be worth a try. Finding somebody to rebuild one of these old hydra-matics is going to be a problem. There are not very many people around who worked on these things in the day. When I had my 54, I found a guy that knew them well and had it rebuilt in 2017. He passed away a couple years ago. Good luck.

 

As Redoldsman suggested, a fluid change is worth a try
There is no filter in these old Hydra-Matics, but there is a screen for the oil pickup.
Pull the pan, and make sure it's clean.
There are two drain plugs on the torus cover (torque converter) top and bottom..
Completely drained, it should take about 11 or 12 quarts to re-fill
Use Dexron III / Mercon trans fluid ONLY.

 

It's worth a try swapping the fluid. Good luck.👍

 

Also, the band adjustment should get verified. This was a matter of periodic service with these transmissions, some still operating have never had this critical aspect checked and set even today. Since yours is slipping with shifts, proper band adjustment may allow further service as-is.

Your report on very dirty fluid may mean the friction material is shedding which is common with cars which have sat for long periods allowing steel parts to rust, then abrading friction material such as frictions and bands. Fluid change, internal fluid intake screen cleaning and band adjustment is certainly worth the try since is does operate now.

Refer to your service manual for the procedure on band adjustment. Some special service tools are made for the job, and they are around in some older shops, and for rent from transmission parts suppliers.

 

Morning all,
I did go ahead and change the transmission fluid. Glad I did. This is what the screen looked like. Shifts great now. I apologize for not updating this sooner. I have been fighting with an over heating problem now. flushed the radiator, checked the distribution tube, replaced the thermostat, new water pump and all hoses. started pouring coolant in the radiator and its leaking at the water pump. now to take it all back apart and see what my issue is now. Block was cleaned very well before i installed the new water pump and gasket. I bought the water pump from Kanter and it came with a new gasket. anyways, thank you all for your help.

Jake

 

That could be the issue.

 

Glad to see your problem was solved so easily (and cheaply)
It's probably a good idea to change the fluid again a couple of times in the next two years.
A lot of that kind of crud that you saw on that screen is probably inside that trans.
When the fluid starts looking dirty, change it again.

These old Hydra Matics were tough.
They were even used in tanks in WW II.

 

Glad it was an easy fix!