The Stovebolt Site Forums The Shop Area Driveline 1954 Hydra-Matic Master Cylinder

Ok, before I completely FUBAR this 1954 Hydra-Matic Master Cylinder (MC) I thought I would defer to the experts. I broke this MC plug back in the late 1970’s before I knew about PB Blaster or much of anything else. Since it did not look like the one I got from the FLAPS I was at least smart enough to hold on to it for all these years. I am fairly sure it is original to the truck (at least I think so…this truck is full of surprises) and since the one in the truck now needs to be rebuilt or replaced, I felt like this would be a good time to tackle this project. Nothing like putting something off for 40+ years. Any ideas? I really want to save this part, especially since I have held onto it for so long. I am fairly certain heat will be involved then maybe build a tool to fit the holes. Am I on the right track?
SLC

Hy SmithLakeChevy, because there is nothing above the main body I think I would drill two holes in the cap 180 degrees apart as close to the threads as possible and try to shrink the cap in to loosen it and possibly turn it out, hope that helps.

Thanks 3B! ...and apply a little heat when I try to turn it out?
Thanks again,
SLC

Since it's off the truck, drop it in a coffee can of Evaporust overnight before trying to get it loose. May surprise you and come right out. 🛠

I just purchased some Evaporust recently so that sounds like a great idea!
Thanks Martin!

Here is an update on the broken MC filler cap. I took Martin’s advice and soaked the MC in Evapo-Rust overnight and then about a day or so longer to remove all of the rust. Wow, I am a believer! The stuck cap threads were actually shining like new metal when I took it out. I then heated the metal and melted paraffin wax around the threads like Jerry (Hot Rod Lincoln) had advised me to do on my carburetor problem. After several failed attempts to get it to budge, I finally called around to several of the local heavy equipment parts suppliers and landed on a jewel right here in Jasper. The guy said that he had a cam action internal pipe extractor that he thought would work so I headed off to the store with my almost new looking MC in hand to see if it would work. The tool was a little big, but I figured I could hone it out a little and get it to fit. It was really stuck, but after applying some PB Blaster and using the long box end wrench for leverage, it finally worked like a charm. I am sure the Evapo-rust, wax, heat and everything else helped. I do appreciate all of the current and previous advice I have received from this site. With everyone’s help, this process, journey, adventure, has been a blast! I still have a long way to go but this was one major step in the most important part of my restoration process, or being able to stop! My planed process now is R (roll) S (stop) R (run) G (go). I had to conquer the “roll” first so I could move the truck into the garage. It probably should have been “S” first, but then that was just part of the adventure!
Thanks again,
SLC

Glad to see you were persistent and didn't give up when things got a little difficult! Now, one more suggestion, if I may- - - -Before reassembling the master cylinder with a new rebuilding kit, soak the entire casting in 90% rubbing alcohol for a few hours. It's readily available (and cheap) at any drug store. Some of the solvents and lubricants you've been using do not play nice with rubber brake parts such as flex hoses and wheel cylinder cups. Since most brake fluid except the silicone-based stuff which really shouldn't be used in a stovebolt system anyway is basically a mixture of alcohol and glycerine, using high-proof alcohol as a cleaning solvent assures you the best chance of getting all the other chemicals out without leaving harmful residues behind. Any residual alcohol also evaporates quickly.
Jerry

Thanks Jerry! You don't know how much I appreciate your help!
SLC