Rear brakes will not bleed
 

I have 1990 s-10 blazer. I have changed the master cylinder, both wheel cylinder and the shoes. the brake light is still on. I can't get any fluid to the rear to bleed them. what gives?

Did you bench bleed the master cylinder before installing it?
Why did you replace the wheel cylinders?


The combination valve is disabling the rear hydraulic circuit which turns the red BRAKE light on, (it's a built in safety feature). The valve needs to be reset, (centered). It can be tricky to do if the valve is really stubborn. There are a few ways to center it so you can bleed the system. Try this first, it will require a hand vacuum pump: Brake Bleeder and Vacuum Pump Kit


Remove the master cover and fill the master cylinder, leave the cover off. Open a rear bleeder and connect the pump to the bleeder. Pump it until the fluid starts to run, then let it gravity bleed until the fluid comes out with no bubbles, (usually takes about 10 minutes). Don't let the master run dry during the gravity bleed. Then close the bleeder and check the pedal, should be firm. Apply a quick jab & release on the pedal and the light should go out. Post your results.

I did bench bleed the master cylinder. the pedal went from mushy to hard but I still can't get any fluid to either line in the rear.

if possible, you or someone pump the pedal and hold it and crack the line open before the rubber line attached to the rear axle. sometimes they collapse not allowing any fluid to come through.

also try resetting the proportioning valve by pushing that little button on it, its probably seized like they all are, sometimes you can tap on it with a hammer to get them to work, one time i got pissed off working on my old truck and just stomped the brake pedal, something clicked and i had brakes again

The reason I asked about the wheel cylinders, is if they blew apart, (rather than sprouted a slight leak) you might want to consider repairing the cause before worrying about bleeding the system. Two things can make them blow, (they don't just blow on their own) and If you don't fix the cause, the new ones will blow too.

I had that for the first time yesterday. Stupid Dodge uses a different hose for each wheel so they are over $30ea. I figured it was a stuck caliper causing it to drag. Turned out it was the hose which let high pressure through and then held it. The new caliper didn't bleed until I put the new hose on.

I have replace all calipers and master cylinder I can not get adequate fluid to back brakes? It is driving me crazy. gravity flows to back but will nt get preasure.? ABS light is on? What to do to reset?
Thanks for any answer.