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Mon Nov 02, 2009 7:53 pm

Guys the other day I had to slam on brakes. At first the pedal was solid, but all at once the pedal took off for the floor. I have no external leaks. It felt exactly like it did the last two times when I found the rubber hoses failed (but not leaking externally).
I had my wife apply steady pressure on the brakes, and found that both rear drums turned with no effort(wheels off, car in the air). I tried bleeding the rear brakes. I had a smidge of air on the LR, but the RR was pure fluid. All of a sudden, the rears no longer turn when holding the brakes. Strange. After another application or two, they are back to turning freely. At that point, I also noted when she is holding the pedal, and the rear drums turn freely, when opening the bleeder there is no brake fluid pressure. maybe just a dribble.
Both rear wheel cylinders are like new, as are the rear hoses. In fact they are probably all less than a year old. I'm guessing master cylinder is failing. I did get a bit of fluid from the rear port of the MC, but I only checked it once, so had I checked it 10 times, I might have found that 8 outta 10 produced no fluid..! Anyone think it is something other than the master cylinder?

Mon Nov 02, 2009 7:57 pm

Sure seems like the master to me.

Mon Nov 02, 2009 8:02 pm

Even if a wheel cylinder is stuck, or leaking some, opening the bleed valve and pumping the brake pedal would pump fluid out the bleeder. So I also suspect the master cylinder.

Mon Nov 02, 2009 8:15 pm

thanks guys! The car has been in the family for 22 years. I have been through a number of shoes, cylinders and hoses, but this is the same MC that was on it when we bought it 22yrs ago. I guess we got our money's worth out of it!

Tue Nov 10, 2009 6:00 am

Guys, I replaced the MC with a new unit. The thing stops as good or better than ever before. It actually locks up the rear wheels now if I brake hard with the clutch in. Never locked ANY wheels before.
BUT, do I have another problem now? The brake pedal is rock hard when I press it down. I have a couple inches(guessing haven't measured it) of travel before I have resistance and then very little movement from the first sign of pressure till it stops. When it stops, you'd think the master cylinder has bottomed out.
I think I can get used to it, and it stops with no abnormal tendencies. I would just like a little better pedal "feel" Should I worry with it, or drive on? Oh, also, I left the brake pedal "rod" attached when I removed the master, and simply guided into the back of the new MC. Could that be an issue? Thanks!