The new master cylinder is installed after bench bleeding. Followed by another hour of bleeding the brakes. No Brakes, no pedal, nothing. Now I am going to make a pressure bleeeder from a piece of flat steel and a valve to hook to my compresssor. Correct me if I am wrong but I will run about 10 psi into the system and cross my fingers. Brent

 

My power bleeder says to use 10 psi. I know you have been over the brakes several times, but is there any way one of the calipers is leaking? Are you losing fluid after pushing the pedal with all the bleeders closed?

I would follow Tom's procedure. If you can get a pedal with just the MC, then the MC is good.

Good luck
Ken

 

I've never tried the valved bleeders but it would seem to me that you need a perfect seal on the threads or you could suck air back into the system when you let up on the pedal, couldn't you?

 

You have a bad master Clyinder man.

If you had air it would pump up.

A leaky caliper would slowly drop to the floor.

Never buy a rebuilt MC...Never

 

When you bled the calipers...
Did you get the exact same fluid flow rate while bleeding the front as you did the rear?

Or was one circuit flowing a lot less fluid?

You need to test the M/C separately as I indicated above. Otherwise you'll be chasing your tail.

 

A homemade pressure bleeder without a fluid tank may not be worth the bother. You will have to unhook it constantly to check the fluid level.

 

Made a pressure bleeder from a solid plate and a air hose hookup. Pushed out fluid but no bubbles thus still no brakes. Have called in a mechanic friend of a friend who is now going to give it a try. My father who has been helping me for the last two days has thrown in the towel. He says he has probaby bled brakes on at least a hundred cars over the last 40 years and has never come across a car as stubborn as this. Brent

 

I would get rid of the fancy speed bleeders and go to standard bleeders and try it all again. Maybe your luck will change.

Brent...

 

You aren't still jacked up by any chance are you? Is the car level? Long shot.......

 

C3 brakes 101-Bubba U final exam grading
A. car moving to test brakes. A
B. car not moving. F
C. car on jackstands in gear. C+
Just want you to verify that the rotors are moving

 

NEW not reman. Best rule of thumb when it comes to master cylinders.

 

This has absolutely nothing to do with the problem, but since we're all sittin' 'round the campfire...

"For pressure bleeding, use bladder-type bleeder tank only, such as Rotunda Brake Bleeder 104-00064 or equivalent. "

I see this all over the place. Theory is, when your bleeder pressurizes the fluid, if there is not a physical barrier (bladder) between the compressed air and the fluid, the pressurized air will actually force air into the fluid before the fluid goes into the system. And... voila.... you have instant air in your brake fluid.

Although I do believe this is true (I work in a lab now and I see this kind of thing happening all of the time) since I have not tested this myself, I cannot vouch for how important the bladder is.

It seems that the big difference between the expensive pressure bleeders and the inexpensive ones is the absence of the bladder.

Lots of guys have apparently done fine with home-made setups.

I'm just throwing it out there because it's one of those things the heavy hitters claim is important.

I'm not pro or con. Just a FYI

PS.... Put some postage stamps on the windshield and send the car to me... I'll fix it for free.

 

i just ordered the motive pressure bleeder and i believe it has no bladder. i can't see introducing additional air bubbles into brake fluid at these low pressures and for the duration of the time we have them pressurized....now perhaps in a commercial shop that has high pressue on this brake fluid continually i could see that happening...

 

The commercial bladder type units also operate at 10 - 30 psi.

 

and do they stay constantly pressurized over time?

edit are these pressurized by compressor air? perhaps its to keep the brake fluid clean and free from contaminants.

 

They are pressurized by "shop" air.... which should be clean, but only if the shop owner made it that way.

I'v e seen some pretty grungy shop compressed air systems.
Water and oil are the primary culprits.

Mine has multiple filters and air/water separators. They are constantly getting fouled, and I am constantly cleaning them. It's a PITA.

The professional bladder type pressure bleeders which I have used or owned have all had a built in pressure regulator. So regardless of the shop line pressure, the bleeder itself sets the maximum operating pressure.... 10 - 30

Shop line pressure would (theoretically) never go up.... but would sometimes go down. So the bleeder was protected.

When I first started working in a lab a few years ago... the researchers were struggling with unreliable compressed air... the building air compressor would fail without warning. Since we use pneumatic controls for our reactor chilled water cooling systems, this would cause a "melt-down"... lots of $$$ and time wasted. I went to Harbor Freight, bought a cheap 5HP compressor, installed a few check valves... and now when the building compressed air goes out, our own backup compressor automatically kicks in... no more pneumatic control issues.

You never know what is involved with an air supply system unless you build it yourself.

 

http://community.webtv.net/MATTGRU/BRAKES

 

Hi..I have a 77 corvette replaced booster and MC ..and i still cant get brakes...were you able to source the problem
Cheers Phil

 

(or your pedal is not activating the MC some how?)

 

Hi thanks for your reply..Have replace both booster and MC with New ..Have good pedal when engine not running but as soon as engine started and vacume comes up..pedal goes straight to the floor.
Any help would be greatly appreciated