My daily driver, 92 Passat doesn't feel to have proper braking. The pedal is a little soft and it is impossible to lock any of the wheels anyway. I recently had to panic stop and it just felt like I was leisurely coasting to a stop. Fortunately I didn't hit anything but it spooked me a little.
There are no seized calipers, they all seem to be functioning properly, wear on pads is even side to side.The e-brake is not on, although I have a stiff cable. I have replaced some brake lines over the last year, the main line from the MC to the proportioning valve and back to the front. Also from the proportioning valve to the rear wheels.
I did notice that the last time I did brake work I didn't get any fluid leaking at the rear. I opened the bleeder screws when I replaced the line and let it gravity bleed first.This was done with the MC cap open. I'm wondering if the proportioning valve might need replacing seeing as how it is original to the car? Or is there a way to reset it? Or check it?
When you lift the car off it's wheels and let the rear wheels droop, the proportioning valve will restrict the fluid flow to the rear brakes, which would explain why you don't see much brake fluid flow to the rear brakes (locate the jackstands under the rear beam to hold the rear wheels in the same position they're in when the wheels are on the ground to avoid this problem).
If the fluid flow is restricted to the rear wheels, it's impossible to bleed the rear wheels properly to remove contaminates and air from the fluid, resulting in a mushy brake pedal.
Also, without the rear brakes fully functional (including the parking brake), the rear brakes cannot self adjust, and as a result, the rear brake shoe/pad clearance will be excessive since the parking brake mechanism will not be able to adjust the rear shoe/pad clearance. This also results in a mushy brake pedal.
Thirdly, as I already mentioned, the parking brakes must be in working condition. If the parking brake cables are seized (and it's sounds like yours are), the parking brake will not work, and not be able to adjust the rear brake shoe/pad clearance. Again, resulting in mushy brakes.
Okay... So 3 days ago I changed the caliper on the rear passenger side because the e-brake wasn't releasing. As usual I left the bleeder screw open to allow the system to "gravity bleed" before doing the pump and release method. The caliper still hasn't filled up so we are back to the original question.I can see fluid at the end of the line and I know that if I pump the brakes it will fill the cylinder. Is there anything that can be done to fix this problem with the proportioning valve or does it have to be replaced?