Hydramatic Pump Seal

[shadetree77]

I've got the engine and Hydramatic out of my '53 Manhattan. I've been told the front pump seal is notorious for leaking. I think I might try to replace this just as I did on the Dynaflow in my Buick. Might as well while I have the trans. out. I have a few questions though.

First, just to make sure I'm looking at the right seal, it is the one that the red arrow is pointing to in my picture below right?

Second, do you have to remove and disassemble the entire front pump just to replace this seal? I didn't have to in my Buick and it looks like it might be similar here. All I did on the Dynaflow was to pull the old seal out, then drive a new seal in using a piece of PVC pipe that went around the shaft. What do you guys think? Will this work on the Hydramatic too?

[joefrazer]

The seal is installed from inside the case. The transmission will have to be disassembled to replace the seal. Been there, done that.

[shadetree77]

Jim, I understand that the torus must be disassembled and removed from the shaft. But the more I looked at the service manual pictures of the seal location and the picture of a new seal being driven into the pump cover it looked to me like it would be possible to pry out the old seal from the pump cover then put the new seal on the shaft, position it on the pump cover, then place a long piece of PVC pipe over the shaft and use it to drive the new seal in. I contacted a fellow that specializes in rebuilding these transmissions and he confirmed my suspicions. You do not have to disassemble the front pump to replace the front pump metal clad seal. He said to do it just like I thought but to be VERY CAREFUL not to scratch the pump surface when prying out the old seal. Then he said to use anaerobic sealant on the new seal and drive it in with a piece of pipe over the shaft. He also recommended removing the bolts that hold on the bell housing to make the job easier. Maybe we are talking about a different seal? I'm going to try this at some point and I'll take pictures and let you know how it goes.

[joefrazer]

I got a closer look at the hydramatic shop manual and there are two seals used on the front pump. The first can be, as you said, removed and installed without having to disassemble the transmission. The second is a thinner gasket that goes between the pump assembly and the transmission case. This is the one I was referring to. After looking at the diagrams, I remember the problems I had with the latter gasket not sealing and trying several different things to remedy the problem.