Mechanics

REAR BRAKE PROBLEM

1998 Chevrolet Blazer • 116 miles

Hey all I have a 98 chevy blazer 4 wheel drive. I had a caliper hang up on me last year. IT was the drivers side rear. So I replaced it and bled the system without any problem. Its been about a year and I just had the other caliper on the passengers side rear hang on up me. I know, I know, I should have done them both at the same time. But I didnt. So today I went out and replaced the other side. New caliper, rotor, and pads. Went to bleed that tire, and nothing. Just a dribble. The peddle doesnt build much pressure, and the little it does build when the bleeder valve is shut, it goes away when I turn the blazer on. So out of curiosity I jacked up the other side and tried bleeding that side. Nothing.I am stumped. I am going to jack up the front and check the fronts to see if I get any brake fluid coming out of them in the morning. If they do spit out a stream of fluid, does that indicate the proportioner valve is bad? Or could it possibly be a MC problem?


Thank you all, and before you guys fire away on me I know I should have done them at the same time.
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Chiefcatchemall
November 4, 2011.




Chances are it is the master cylinder. I test them by removing the steel lines, one at a time, and see if I can hold my thumb over the line opening on the MC. If I can on one and not the other, it's bad.

But my breaks were working fine 5 minutes before I started working on it? That is what I dont understand. It just blows my mind that it would just go bad as I am working on it. Doesnt make much sense to me. I dont want you to think that I am telling you that you are wrong because Im not. I really appreciate any insight! Anybody else with any other ideas?

Tiny
Chiefcatchemall
Nov 5, 2011.
It can also be the flex line going to the rear axle, assuming it uses one input line with a tee for both rear wheels

Wrenchtech
Nov 5, 2011.
Also, did you push the caliper pistons in without opening the bleeder valve on the calipers? If so, you may have damaged the plungers in the MC. It happens often, but people still do it that way to depress the caliper. When I was taught by Bendix, I was told never to force the old fluid back through the system into the MC. Open the bleeder on the caliper and allow the fluid to push out there. Let me know what you find or if you have questions.
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Yes it does tee off for both rear wheels. Never really thought about that. I did not compress either of the pistons. So I am ruling that out. When you say flex line what exactly is that? I think I know what you are talking about but I dont want any confusion. Its the main line that leads into the tee correct? I know proportioner valves normally dont go bad, but theoretically it does make sense doesnt it? If I go out in the morning and I am getting a sharp stream of brake fluid out of the front 2 calipers, but nothing out of the back, it COULD be that right?

Tiny
Chiefcatchemall
Nov 5, 2011.
The flex line is a reference to the rubber brake hose at the caliper. They can go bad inside and block the flow of brake fluid. However, both at the same time is odd. Yes, it could be the proportioning valve, but unlikely. My guess is the MC. Try the trick I said about placing your thumb over the ouputs at the MC. Cover it so if fluid sprays, it doesn't get on anything.

It has a single flex hose that feeds both wheels and that can be the problem.

Wrenchtech
Nov 5, 2011.
Well it has a main metal line that leads into the tee. Then it splits off, one to each tire. Still metal line wrapped in hard plastic. Then it goes to the flex line. 1 flex line to each caliper. I am going to go try to bleed the fronts, and check the MC.

Tiny
Chiefcatchemall
Nov 5, 2011.
There has to be a flex line to connect the frame mounted steel line to the moving rear axle.

Wrenchtech
Nov 5, 2011.

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