Brake bleeding issue

[ryangreen19]

I have done an upgrade to a front discs off an 85, I have been able to bleed the front wheels fine with a vacuum accessory. The rear discs, which I completely rebuilt with new cylinders and lines is not going so well. I can get a good vacuum, about 22 inches and its holds, but very little fluid comes. A virtual trickle next to the front. And on both sides. I don't have any kinks in the lines and since I can get a vacuum to stick, I likely don't have an issue with leaks do I?

Is this likely an issue with the proportioning valve or MC? I got a new proportioning valve, the pin on the front is flush.

To top it all off I need this running by next friday, we are moving to a new place.

[hugger6933]

Did you use a disc disc MC? If so what about the prop valve is it Disc disc as well. You know that for the rear of the brakes you r not gonna have lots of volume of fluid. Jim

[ryangreen19]

Proportioning valve is disc/drum. MBM pvks-2, bought new. I forgot to mention, I added hydroboost from a 93 astro as well. I got this from a wrecker. Unit looked to be in good shape, no leaks. I did not split the unit. So the master cylinder is disc/drum as well. Power steering and theoretically the hydroboost are bled.

Can you clarify on the volume of fluid comment?

Even with the front brakes bled, I have very little pedal feel.

[ryangreen19]

I checked the function of the proportioning valve with a test lamp, it indicated it was centered. So I then thought to test the MC. I disconnected the line from the MC to the rear side of the prop valve and stuck it in a jug of brake fluid. Was able to pull fluid to the rear instantly. So apparently a bad rear side to the MC. I have a rebuild kit I am putting in this afternoon.