Need help bleeding brakes
 

I installed a new brake booster and master cylinder and need to bleed the brakes.I bench bled the master cylinder - it wasn’t a new one but it was only used for a few hundred miles.

I put my vacuum pump on the right-rear brake and pumped up to 20psi pressure. No fluid came out after a lot of pumping. The mc is full of fluid.

The bleeder screw was well open.

Any ideas?

Re: Need help bleeding brakes
 

It has a dual master, right? Perhaps you triggered the shuttle valve? I'm guessing that you're working on the '69 in your signature?

Re: Need help bleeding brakes
 

Did you bench bleed the brake master cylinder? I always do this to confirm everything is working correctly.
I also leave the lines loose at the MC and pump the brakes till I get some seepage at the joint then I fully tighten the fittings.

Pump the brakes, see it that works. If not, it is easy to get the rod between the pedal and the MC out of adjustment when retrofitting brakes. As in it could be too long. Confirm you have some slack there.

Re: Need help bleeding brakes
 

Did you try (pushing or pulling) the button on to proportioning valve?

Re: Need help bleeding brakes
 

Just throwing this out there. I had the same problem, turned out to be the original rear brake hose from frame to diff was blocked.

Re: Need help bleeding brakes
 

If you remove the vacuum pump, open the bleeder, and push on the brake pedal, does any fluid come out? The second sentence of his post stated he did.

Re: Need help bleeding brakes
 

Oops, thanks for the correction

Re: Need help bleeding brakes
 

That's a good point. An easy way to verify would be to close the open bleeder and hook the vacuum pump to the other side. Of course, if it has the shuttle valve and it has moved, switching bleeders won't help. When the right front wheel cylinder on my truck started leaking, I just went to disc brakes (and rebuilt the front end, which it probably needed at 210k miles). No idea how old the rear hose was, so it was a no-brainer to change it out.

Re: Need help bleeding brakes
 

Pull your bleeder screw all the way out and see if the hole is not plugged, you wont loose any fluid if you put the cover back on the MC .

Re: Need help bleeding brakes
 

Make sure the button is pushed in on the proportion valve, you can use a c clamp. There is a tool made for it. In forbleeding.