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I am missing something between my Master Cylinder and Booster?
Dear All: My Toronado 67 keeps leaking brake fluid from the back of the master cylinder where it joins the power booster. This happened to me since I have memory, no matter where I source the cylinders. Looking at the CSM the bendix cylinder shows a Splash Seal and Retainer which I never had in my purchased brakes. The back of the master cylinder shows a groove and depression which I always thought they are there for a purpose. All in all I will like any insight about if something is missing in the union between the cylinder and booster. Best. Raul.
A picture of the back of your master cylinder and the front of the booster would help. The only thing on the booster is a rubber cup seal that is surrounding the actuator pin, nothing on the master cylinder.
While there is a rubber seal between the M/C and booster, the master cylinder should not be leaking, period. That seal is there to seal vacuum in the booster. It has nothing to do with sealing brake fluid in the M/C. Any fluid coming out of the back of the M/C means that the seals inside the M/C are bad, period. Are you sure that isn't fluid overflowing the back of the reservoir and running down the back of the M/C?
Joe, of course you are correct, the moment I sent the question I regretted it, although I will like to know is there is something missing in the coupling, it was clear to me the leaking fluid was not normal. I am now wondering why this leak keeps happening even with new cylinders (Sourced form Rockauto). I got another one now I will see how it goes.
You are correct, the cylinder is brand new while the booster not. The idea was to show the groove and depression in the cylinder for shich I have no explanation. Tx
Eric: Good point, actually I always thought about it, but not sure I am doing it correctly, I use the Kent Moore Tool for Bendix Booster (different for Moraine) but since the Booster its not original it will help me other guidance beside that. Best. Raul.
Looking for my question in this forum i found someone with exactly the same question and figure who provided once again a spot on response?, Mr Padavano. I finally have a source for the seal and also an explanation of a possible cause: The seal prevents vacuum to reach the piston and sucks fluid into the booster. This will explain why no matter which cylinder I put there is always a leak very possibly also because my Booster may not be in the best shape and leaks more vacuum than nominal. Worth a try.
f there is no gasket between the PB vacuum booster and the master cylinder the following will occur.
The PB booster will constantly hiss and pull vacuum from around the plastic power piston supporting the rod that pushes into the master cylinder. When vacuum is sucking here - it literally pulls brake fluid past the master cylinder piston seals and right into the PB booster. Decades ago when I services these EXACT Corvette parts I often found a cup of brake fluid pooled in the bottom of the PB booster. That is not good. Either the seal was absent - torn or worn. This is true for every 63-67 Corvette as well as 68-82 Corvette including similar vintage Delco Moraine PB.
The vacuum in the booster is less than 14psi. The pressure in the M/C when you press the brakes is over 1000 psi. If the seal can hold 1000 psi, it isn't going to leak at 14 psi.
Joe: Difficult to argue that!, but also difficult to understand no matter which source of cylinder I procure, it keeps happening. There must be another cause.
Joe: Difficult to argue that!, but also difficult to understand no matter which source of cylinder I procure, it keeps happening. There must be another cause.
I've heard countless stories of new, remanufactured, master cylinders leaking. Sometimes it takes multiple times to get one that doesn't leak
