Please Help BRAKE Problems AGAIN!!

[natedog437]

I have been having brake problems for the longest time. Everything has been replaced on my brake system like my master cylinder, pads, rotors, etc. There is still no pedal. There is no air in the lines and the car will stop, but it is only seconds after it has been on the floor. I thought it may be the brake booster, but my mechanic is saying the master cylinder is fine and it isn't my brake booster, it's the combination valve which consists of a metering valve, a differential switch and a proportioning valve. He is telling me that it is bad because I'm not getting any rear caliper braking. Could he be correct? The pedal feels completely mushy till it hits the floor and then has enough pressure to stop, the master cylinder that he put on has been tested and is good, and there is no air in the lines. Please help!

[180fan]

Is your check valve working?

The proportining valve is in the master. Only other thing I can think of is a blockage in your lines that run to the rear that's holding some air in.

[natedog437]

Is the check valve located on the Combination Valve?

[180fan]

nah the check valve is that bulge thing that's hooked up to the booster. If that thing's busted it could be why it's a bit more difficult to brake. blow air into one hole and then the other end. Air will go through only one way.

[natedog437]

So does that mean our cars don't have combination valves that are underneathe the car that has the brake lines running throuhg them?

[bruinbear714]

I know this may sound a little obvious, but did you check for a leak for the vacuum line that goes from the brake booster to intake manifold?

[cdlong]

there's an adjustment for the rod that connects the pedal to the master cylinder. it's probably too far out and doesn't actuate the master cylinder until far down in the stroke.

it's not the booster or the vaccum line or the valvve, that would make the pedal harder.

the prop valve (not combination valve) is built in to the master cylinder and assuming it was new when you replaced it, it should be good.

my only other thought is a bad master cylinder.