I just installed a new master cylinder and proportioning valve. The master cylinder was extensively bled but the prop valve was not, I was hoping to just blow thru it. It is difficult to get fluid to the back brakes. When I switched to the front they bleed fine for a while then the pedal got hard like in the back, with little fluid. My next move was to take the master cylinder and prop valve out together and bleed straight thru. I've bled plenty of brakes including this vehicle many times, is there a reset trick for the prop valve?

 

ive never had a issue with them not pushing fluid through all though ive heard of other people talk about it. everytime i run into this problem its usually due to a crap load of air in the master cylinder itself. if you didnt bench bleed the master before installing it you might want to do, doesnt really take long to take back off.

 

I had bled the master cylinder extensively. I ended up intercepting the brake lines at the ABS unit and wrapping them back to the master cylinder reservoir. I got some air out and now the brakes bleed.

 

Scratch that...brakes go to the floor. I must have some massive air pocket. I had put clear hoses over the brakeline ends at the ABS but only pumped until bubble cleared, shaky set-up. I'm going to disconnect the prop valve to abs lines and use flared fittings at the prop output to wrap back to resevoir. Pump and tap with a wrench...alot. I had plenty of clean, air-free fluid move through but the pedal has been much harder to push than I remember during bleeding. Must be air in the prop valve, master cylinder extensively bled.

 

I bought a cheap vacuum bleeder which sucked out a lot of air. Looking okay.