Power disc brake proportion valve question

[Randy Beck]

I have just swapped my front drums for a new set of power disc brakes. When trying to bleed the brakes, I can't get any brake fluid to the rear brakes. I have fluid to the front brakes. I unhooked the brake line that comes from the rear to the prop valve and pumped the brake pedal and no fluid come out of the prop valve. I figured it was a bad valve. I have a spare and I swaped them out and I have the same problem.
Any ideas on what's going on?

[fordman]

maybe the line from the rear supply of the master cylinder is clogged. it has two of them. one for the front and one for the rear.

[Randy Beck]

Both lines are brand new, so is the master cylinder. I have fluid coming thru the line to the prop valve but nothing coming out.

[benm78]

I believe that you need to re-center the piston in the proportioning valve.

Here is what I found in the MP Brakes catalog re: the valve:

you can also try www.mpbrakes.com to get this directly from their catalog.

"1: Using test light, attach clip to a positive and touch the point of the tester to the electrical connection of the ccombination valve.

2: If NO light goes on, the valve system is operating correctly. No further testing is required.

3: If light goes on, this indicates the pressure differential valve in the combination valve is stuck in the front or rear position.

4: Bleed brake system to determine which system (front or rear) is not getting proper flow. (which it appears you already know)

5: The system with flow must be opened for flow to alter the pressure on the opposite side of the pressure differential valve to center valve.

6: Slowly depress pedal with steady pressure until light goes out. When light goes out close the bleeder.

7: Your system is now centerred. Bleed complete system following enclosed bleeding instructions."

Good luck,
Ben