87 gmc rear brakes

[nascarmikeb]

doing some rear brake maintenance, i see where i am not getting any fluid to rear brakes, either side. I saw a few post back about depressing the rubber button on the distribution block. My question is, what is best way to keep it depressed while bleeding, other than holding it? Also what is the bleeding sequence again. I have good front brakes, do I need to bleed them as well?

Wheel cylinders look good, no leakage.

[nascarmikeb]

Ok, so i got fluid to the rear wheel cylinders via gravity flow. I bled rear, but I still dont have any movement in the rear brakes. the wheel cylinders are not budging. is it possible that they could be frozen? should i go ahead and replace them?

secondly, I pulled the rubber boot off of the brake distribution block to depress the button. The button was already depressed, even after bleeding the whole system, it never popped out. Should i be concerned?

[Desert1957]

Start over

*Bench bleed the Master Cylinder (posiblity its air bound)
*Reset button on the proportioning valve (It stays in once reset)
*Check for pressure at the Master cylinder outlet fitting before the proportioning valve
*Check for pressure at the inlet and outlet of the proportioning valve
*Check brake pressure at the fitting on the rear , before the rubber line
(Its possible the rubber line is collapsed causing a blockage)
*Check for pressure at the inlet of each wheel cylinder

My point is start at the Master Cylinder and work your way to the wheels, at some point you will find your problem. You will need two people, one to press on the pedal and you to crack each fitting loose to observe what's going on.

Desert

[Keith Seymore]

Originally Posted by Desert1957

Start over

*Bench bleed the Master Cylinder (posiblity its air bound)
*Reset button on the proportioning valve (It stays in once reset)
*Check for pressure at the Master cylinder outlet fitting before the proportioning valve
*Check for pressure at the inlet and outlet of the proportioning valve
*Check brake pressure at the fitting on the rear , before the rubber line
(Its possible the rubber line is collapsed causing a blockage)
*Check for pressure at the inlet of each wheel cylinder

My point is start at the Master Cylinder and work your way to the wheels, at some point you will find your problem. You will need two people, one to press on the pedal and you to crack each fitting loose to observe what's going on.

Desert

x2

Looks like a very good plan. In the end, if you've got fluid/pressure at the inlet of the rear wheel cylinder(s) and no movement of the plungers, then you know they're frozen up.

K