Thread: No Brakes

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Ok well, I had drove the car earlier in the week with no probs , then a few days later, go to take it out of park, brake pedal drops to the floor and she starts rolling down the driveway . Opened to MC and there was no fluid, looked underneath and at the tires and I don't see any fluid anywhere

I would think if it was a wheel cylinder there would have been some fluid on the inside of the tires, but all dry, haven't taken the tires off yet though...

So I replaced the MC since it wasn't very expensive and still nothing . When I go to bleed the brakes, the back brakes will bleed perfect, but once I get to the front, it seems as if the air never ends, I am thinking a brake line somewhere, but can't find any leaks so far.

If anybody has any other suggestions, I will be happy to listen

Oh yeah its for a 51 Chevy Deluxe, Drum/Drum, manual brakes

If ya keep filling that master cylinder and keep pumping it dry, the fluid has to be going somewhere. If ya look hard enough your going to find a puddle. Jeez, there's only a very limited number of places that brake fluid can go---

I've been pumping this new MC like crazy and its not emptying, haven't found any puddles YET, but pedal still drops to the floor

If its not dropping in fluid level, and your unable to bleed fluid from the front brakes, then it is not pumping fluid. Did you bench bleed the master cylinder?

Gotta ask.....a 51 chevy master cylinder is not a dual cylinder.....all four wheels are on the same piston in the master cylinder. How do you get the rears to bleed "perfectly" while the fronts do not? Do you get high pedal on the rears?

Thanks

Mike in tucson

Got any crimps in your front lines?

did you get the correct M/C? there is 1 specific for the powerglide cars which from my knowladge is a little diffrent than the standard shift M/C..

I wish I could tell you more but I'v never even pulled a wheel off of my '51, I'v had it 5 years now. been working on other things, it stops and goes just fine.

Originally Posted by brianrupnow

If its not dropping in fluid level, and your unable to bleed fluid from the front brakes, then it is not pumping fluid. Did you bench bleed the master cylinder?

It pumps fluid when trying to bleed, but there are constantly bubbles in it...when I'm bleeding them, the pedal will begin to get stiff, but then when you stop, close everything back up, pow right to the floor again...

I did bench bleed the master cylinder according to the instructions that came with it...should I do it again?


It doesn't have the original MC, its got a dual reservoir one for a corvette w/manual brakes.

The reason that you bench bleed a cylinder is to get all the air (as in bubbles) out of it. Bench bleed it again, and keep pumping it untill there are no bubbles. You can do this right on the car by disconnecting the brake lines, taking the cap off, and make up a set of short lines that go from the ports on the master cylinder and curve back over the top so that they squirt back into the master cylinder. Fill it with fluid, and keep pumping untill there are no bubbles coming out of the lines nor up from inside the cylinder. Then disconnect the dummy lines (don't worry, the fluid in the cylinder won't run out when you do this) Then hook up your regular brake lines and bleed the passenger rear wheel first, then the drivers side rear wheel, then the passenger front brake, then the drivers side front brake. NOTE while you are bench bleeding the cylinder, wear safety goggles so it doesn't squirt in your eye---really bad stuff if that happens.

That is a Class A PITA job on an older car with the MC under the floorboards. I would look for a line restriction somewhere on the line going to the front - there is a T somewhere on this single reservoir system, might be at the MC itself. I'd start there. I would also look at the brake light switch - I believe it to be hydraulic vs the mechanicals of later. Is it restricting flow? Is there a kink in a steel line? A rubber front wheel cyl. line? Is the new MC any good - have the piston seals gone bad from long shelf life - rust? Is there a check valve in the MC? All under floor MC drum/drum have one as the wheel cyls are higher then the MC.