Question about 1999 GMC Envoy

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Replaced back caliper and it wont get fluid already opened valves by master cylender amd break booster think new caliper bad

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Did ya replace lines

Posted on Jun 18, 2014

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Posted on Jan 02, 2017

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SOURCE: 1986 gmc sierra 1500 front rt brake locks up

check brake lines they may have gotten pinched very commonok new c/k trucks when you crank the torsion bars up to far you may have hit something and pinched the brake line check those before messing with the master cylinder those are a real pain

Posted on Sep 21, 2008

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SOURCE: I seem to have a problem with my hydro breaking


Posted on Aug 16, 2009

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SOURCE: tried to bleed brakes after

Usually, its not the master cylinder, but you may have air in the master cylinder. Get another person to help you bleed the brakes. Make sure the master cylinder is full of fluid and loosen the bleeder screw at the caliper. have the other person slowly depress the brake pedal. When the pedal is all the way to the floor then you need to tighten the bleeder screw and have the other person slowly let the brake pedal up. You will need to repeat this procedure several times before you will see any fluid coming out of the caliper.

Posted on Dec 18, 2010

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SOURCE: Replaced all brake lines, rear

It sounds as though where the rear brake lines meet up with the master cylinder; there is probably a piece of dirt in the lines that could be blocking any fluid from getting in. To test this, I would remove the brake lines from the master cylinder and then remove the master cylinder. Once done, have the master cylinder cleaned inside out. This will remove the dirt particles that are clogging your lines.

Posted on Aug 22, 2011

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SOURCE: Have a GMC 2004 XUV

Your truck is equipped with what is called an active ABS brake system, this means the brakes system is pressurized by a hydraulic brake control block that has a powerful electric motor that pump brake fluid into what is called a brake fluid pressure accumulator. The ABS system also contains a traction control system which is able to apply brake pressure to the individual wheels to stop wheel spin or skidding or release pressure. What this all means is the ABS/Traction Control System can apply the brakes without you ever touching the pedal, the pressure is applied through very strong pressure "POP-IT" valves, these valves can stick and this causes the brakes to be applied and burns up the brake pads and rotors very quickly. In order to correct this the ABS hydraulic control valve under the hood (block with all the brake lines connected to it) is defective and will need to be replaced to correct this problemin most cases. This problem may not set any codes or trun on any warning lights like the ABS or Traction control lights. The module requires special tools to replace and bleed out the air, so it must be done at a well equipped brake shop. The part comes in remanufactured form, here is the part number and the price of the ABS Hydraulic control unit (GM calls it the ABS Modulator valve). There are two parts to the system, the valve and the control unit, either may be the cause of the problem, its part number is also below.
I would replace both parts as one repair.
ABS Modulator Valve
ACDELCO Part # 89027152
VALVE,BRK PRESS MOD 2 WHEEL DRIVE; w/4 WHL DISC BRK(JF8); w/o Traction Control(NW7) $303.79 (price source is

ABS Control Module
ACDELCO Part # 10356388
MODULE,ELEK BRK CONT 2 WHEEL DRIVE; w/4 WHL DISC BRK(JF8); w/o Traction Control(NW7) $232.89

Posted on Sep 17, 2011

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02 Ford Explorer sporttrac xlt. New rotors calipers pads and master cylinder. Bled it twice stream looks good new fluid. One day breaks stick then the next no breaks Break light on Proportional valve?

For some reason these vehicles you need to bleed brakes several times, had same problem, so air hangs up in lines somewhere it apears. When you say brakes sticks, describe it better, locked up, or dragging on rotors?

Apr 21, 2015 | 2002 Ford Explorer Sport Trac

1 Answer

My brakes are locking up after i drive my car around 20 min. I have replaced everything from the master cylinder to the calipers including hard and soft lines. New fluid and bled them thoroughly. When it...

To and from the master and calipers. Did you replace the calipers also? Lock ups usually occur when a brake hose is bad or the caliper is bad/binding. Drive it and check the wheel the gets the hottest. Short drive. They get really hot, be careful( will take the skin off your finger). You can get new, bad calipers. The booster and proportioning vavles will not cause a lock up.

Oct 15, 2014 | 2002 Hyundai Accent

1 Answer

My 2005 chevy colorado front breaks locked up and caught fire on the front right side I replaced the brake pads rotors master cylender abs pump and calibers and the two small break lines on both sides...

Sounds to me that your power brake booster is bad or your portioning valve might not be working correctly there is a button on the portioning valve that can be pressed try that or replace it!

Nov 14, 2013 | Cars & Trucks

2 Answers

I am working on a 1993 f-350 with a 7.3 diesel the truck came to me with the brake pedal going to the floor... the customer had already put 3 new master cylenders on it along with a new brake booster......

I would ask where you got the master cylinders from. Were they new, or rebuilt? If the front brake pads look good and no apparent problems from the calipers, it can only be 2 problems. First, is there a leak somewhere in the system. If you have confirmed that there is none, then the master cylinder is 'bleeding' from front to back. Air wouldn't be a problem as you seem to have bled the brakes well, but the only sure way to know is using a bleeder. They run from a simple hand vacuum device to an air powered device which forces brake fluid thru the system.
Since your 'customer' replaced the booster, make sure the plunger rod is set correctly. Perhaps it is not set at the correct length, in which case you will never get a pedal. Diagnosis for this is a pressure tester to see if any pressure is being generated by the calipers.
Good luck. Hope this helps.

Sep 22, 2011 | 1993 Ford F350

2 Answers

Changed brake pads and used a c-clamp to retract the piston in the caliper, never bled the brakes and my wife was driving the van 2 weeks later, applied the brakes and the peddle went right to the floor,...

Bleed the brakes, but it will probably still feel spongy. When you compress the Caliper you need to open the bleeder valve to release the pressure. It sounds like you busted the diaphragm in the proportioning valve. It is a costly mistake but one made alot now that more and more vehicles have anti-locking breaks. If bleeding and replacing the fluid do not help at all then I bet on the proportioning valve.

Apr 24, 2011 | Chevrolet Uplander LS Cars & Trucks

4 Answers

I replaced my front pads ,master cylender, adjusted rear brakes and the pedel is better but still wont lock up the tires even if you press pedel to the floor all service was done by a pro mecanic help!!

has brake booster been checker out? has vacuum line to booster been checked? has the flex brake line that goes to the divider valve on rear end been checked to make it is free of obstruction?

Sep 18, 2009 | 1990 Chevrolet K1500

2 Answers


A bad brake booster will result in a hard brake pedal, stiff and more effort required to stop the truck. Here are my questions to you, first, you said you replaced the master cylinder, did you bench bleed it before you installed it? If not, there IS still air in it, regardless of how much you bleed the brakes at the wheels. Second, when you bled the brakes, after changing the calipers and master cyl., did you also bleed the proportioning valve? Sometimes air can get trapped in the valve, and its almost impossible to get it out bleeding just the wheels. And lastly, when the brake light comes on, does the abs light also come on with it? Air can also get trapped in the abs control module too.

Aug 11, 2009 | Chevrolet Tahoe Cars & Trucks

1 Answer

1982 buick riviera replaced master break cylender stiff breaks

Either your power booster behind the master has failed or the vacuum line or check valve is restricted or leaking.

Jun 15, 2009 | 1990 Buick Riviera

1 Answer

2002 tahoe breaks lock up during driving

It sounds like the rear calipers are bad. Raise the rear wheels and see if you can turn the tires. If you can't, open the bleeder. If you still can't replace the caliper. If you can turn the wheel after you open the bleeder, replace the brake hose to that wheel.

Apr 12, 2009 | 2000 Chevrolet Silverado 1500

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