The Stovebolt Site Forums The Shop Area Engine Shop Water Cooled ? ? Hydromatic

Ok so now I've found that yes the trans is water cooled (or at least it has H2o plumbed into and out of the pan)... I've heard that some of these trans were like that...? ? I'll try to find some numbers on it tomorrow... dj

The hydramatics I worked on back in the 1950's had a small heat exchanger mounted beside the transmission, with short hydraulic lines from the transmission to the cooler unit, and heater-hose sized tubing plumbed from the engine to the cooler. I don't think I've ever seen one with coolant going into the transmission itself. It's possible there might be a loop of tubing going through the pan where heat transfers to the coolant, but it's probably a pretty scarce setup if that's how yours works.
Jerry

Do you have lines plumbed into the radiator from the transmission?If so your trans. fluid goes into your radiator and circulates in its own tube,heat transfers into the radiator,and back into the transmission.

I've heard of some that were in military stuff like tanks had cast iron pans with water ports. Not sure if that was for cooling or maybe heating purposes. Not having a torque coverter, these units didn't create much heat. Seen an old Allison with such a pan once. It was in a refuse truck behind a White gas motor.
Doug

I know just about nothing about Hydra-Matic transmissions. However, over the past few years, I have obtained some Chevrolet & GMC manuals that cover various mid-50s Hydra-Matic transmissions (because I am restoring a 1954 Chevrolet 1/2 ton truck that has a Hydra-Matic transmission).

Below, are a few photos of the cooling unit in a 1955 Twin Hydra-Matic transmission (used in 620-950 series GMC trucks). This transmission was basically two four-speed Hydra-Matic transmissions mounted on top of each other (and could have come equipped with a 2-speed or a 3-speed reduction unit). A 21 forward speed Hydra-Matic drive-line must of been a thing of wonderment.

I do not know what sizes of trucks with Hydra-Matic transmissions used a cooler in the oil pan but maybe the photos below will look like the transmission in question.

http://1954advance-design.com/Web%20images/Twin-H-M-cooler-1.jpg

http://1954advance-design.com/Web%20images/Twin-H-M-cooler-2.jpg

I also have a few pictures showing a similar cooler-unit in the pan of a 1954 4-speed model 254 Hydra-Matic.

the heat exchanger is to regulate temperature. To help raise the trans temp in cold weather, and to cool it in warm weather.

Wow now that's alot of info. In this case the inlet lines do go right into the pan just like in the pics you linked me. And as I said one goes to the rear part of the drivers side of the engine block and the other goes to a y type fitting on the front passenger side of the engine along with a heater hose. Also the filler for the trans fluid goes into the side of the pan between the two exchanger lines. I must say I kinda wondered about if this sys was used to heat also. I was told these Dayton vans were built for the nuclear projects of the day, (military relation) GMC, Dayton T. Brown nor the US gov recognizes this vehicle to have ever been built nor will they recognize any involvment in this vehicle. Yet there is a GMC serial number/GVW tag in the engine compartment. ????? Anyway thank you all for the info. It's coming along and soon to be on the road. Oh by the way no we don't have the windshield, it was shot up in Portland OR years ago and that's why it hasn't been run in years. We have found some companies that can make one though, find out about price Monday. Ckya Doug

yes that's it for sure. The water lines go right into the pan it even has the Harrison name stamped into the pan