I have disc brakes on my Challenger. The fluid will not go through the proportioning valve to the rear brake line so I have no rear brakes. The only place I can get fluid is the passenger front wheel. I can pump up the pedal and nothing releases pressure except the right front.

The master cylinder is remanufactured NAPA unit. The wheel cylinders are all rebuilt. New brake lines front to back. I have installed 3 different proportioning valve units and have the same problem. I

I disassembled two of the units and cleaned them out and thought I had it working but it still doesn't work.

I have the car on my lift and notice that fluid is dripping out of the back of the master cylinder when we are trying to bleed the brakes. I can't pull fluid down to the front brass block with my air-powered brake bleeder.

There seems to be a little fluid leaking from the brake switch, too.

I'm thinking it is the master cylinder. Any ideas? I've been building Mopars for 25 years and I have never had this problem before. Please feel free to recommend, critique, etc.. I'm stumped.

Rick