Brakes not working?

Hi,

You did everything. Are any of the brake hoses expanding when you press the brake pedal? Are you certain it only has rear ABS and not 4-wheel ABS? Are you able to pump up the brakes with the engine off? Are the rear brakes properly adjusted? I assume they are disc brakes since you mentioned RABS, but just wanted to confirm.

If you lift the vehicle off the ground, does depressing the brake pedal apply resistance to any of the wheels?

Since I was thinking you have already done everything correctly, I did some digging. Did you have the power brake booster removed? If so, see pic 1 below.

Also, when you bleed the brakes, are you starting on the right rear, to the left rear, to the right front, and ending on the left front?

Let me know.

Take care,

Joe

Little back story. The problem I am having now is the reason I started doing all the repairs this far.
The truck has front disc age rear drum.
Power assist has been replaced. I removed to check if it was installed properly as you asked. I only get resistance on rear wheels. And yes, brakes have been bled properly. I even took to a shop to bled to make sure I did not notice any lines bulging with brakes applied. Brakes were not pumping up running or not until I replaced master cylinder for second time now, they will pump up slightly while not running.

Hi,

Was the fluid control valve reinstalled on the new MC? See pic 1 below.

Joe

Yes, it was reinstalled. I was having this prob before I started doing any work.

Based on everything you indicated, the brakes should work perfectly. If the push rod is adjusted and everything is new, the fluid control valve itself is the likely issue.

When the brake pedal is applied, the full brake pressure passes through the fluid control valve to the rear hydraulic circuit until the valve's split point is reached. Above its split point, the brake master cylinder fluid control valve begins to reduce the hydraulic pressure to the rear brakes, creating a balanced braking condition between the front and rear wheels.

This is the only thing left that I can think of. You should have a pedal. You indicated reinstalling the valve. Was it new or the original one?

Let me know.

Joe


.

It was an original valve. Also, I was thinking it may be centering valve, could this be issue also? Or has electrical connector is there a way to test it, or is this not an option?

Also, the proportioning valve in theory should only affect the rear brakes, correct? I know I have a unique situation just asking for my own info. But I do have a friend with a Chevy truck that is having exact same problem, so, we are trying to figure his out at same time.

Hi,

You are correct as far as the valve is concerned. I have a question. When you bleed the brakes, do you get fluid from the front calipers? If you do, are the bleeders at the top portion of the calipers?

Joe