Still going on the brakes... I have a master cylinder, power booster, and distribution block restored by White Post. Assembled it all onto the car. Bled the 4 wheels, and did get fluid for a while (in hindsight, feels like I just drained the lines). Did a "bench bleed" while mounted in the car, and got one pedal pump's worth of fluid out of the MC ports, then no more. Attached a pressure pump to the MC, pumped it to steady pressure 5-8 psi and holding. Nothing from the wheels, so I unscrewed the MC output ports, and nothing comes out. I tried pumping the pedal too, nothing.
Am I missing something, to get the fluid to "go"?

Also, the pedal is making a mechanical thunk about half way down the travel, that doesn't feel right.

Any suggestions?

Thanks.

 

Did you bench bleed the master cylinder in a level position in a vise?

 

No, I already mounted it before I learned that (I kept asking friends how do you bench bleed when there are no bleeder screws, then finally turned to youtube).
So I tried to "bench bleed" it in place. That's when I got a little out of it from pumping the pedal, but then no more. The syringe approach didn't work at all.

This is a 4-drum car, with just two output ports on the MC, by the way.

I can try it. If the MC is bad, it'll have to come off anyway.

Does removing it from the car make a difference, with nothing coming out at all? This feels more "blocked" than just air bubbles (but I don't know MC operating details). Shouldn't the pressure pump have pushed it through?

 

Bench bleeding it now - might as well to be sure. Those 2 bolts are easier than anything else going on!

 

ok, pulling it at least I can see more of what's going on. Pushing on the piston was very hard. It initially only moved 1/8", then I pushed harder, and now it travels about 1/2". As before, one "pump" of fluid came out when I got it to move that 1/2", then no more. I push it in and out that 1/2", and no more fluid is moving. How far should it travel, and how hard do I need to push?

 

How far in? I'm not sure, but more than 1/2". While bench bleeding have you set up a return hose/tube from the ports back to the reservoir with the end of the return under brake fluid so it doesn't suck air back in?

 

Based on how hard it is to push in and not further than it travels I am thinking you have a bad master cylinder. I might be wrong but that is my guess.

 

Yes, I did the adapter nozzles with tubes back into the reservoir, then a screwdriver to push the piston. This is all swirling around that something seems mechanically wrong - this isn't air in the system. It was just restored, so I'll give White Post a call tomorrow, see how to proceed.