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Re: brake is sticking
Get the brakes to lock or stick then lift at least one wheel thats locking up. loosen the two bolts to the master cylinder and pull it back to see if the wheel frees up. if not crack one line at a time to see where the pressure is held....front , rear etc...
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The most obvious cause for a hard pedal is simply not enough vacuum. Check the hose running to your booster.could be a bad check valve in booster. To check remove valve from booster hose, Blow through the valve, if you can blow through it, it is bad. if you cant its ok! With car off. Pump the brakes until all air is out of booster. Hold brake down, then start car. if the pedal sinks a little. the booster is ok. If above fails, replace booster. If need be, you can check the rear brakes and see if one is sticking first! Make sure the caliper pins are well greased and slide good. God-Bless! a sticking caliper will cause a hard pedal.
Sounds like you have an air lock in your distribution block or it could be a bad distribution block all together. Sometimes you can tap it lightly and the air lock will bleed out. Also check your vacuum booster. If it is real hard to press the brake petal down, with the motor running, the vacuum booster diaphragm is blown, or there is a vacuum leak in the line to the booster. Pull the vacuum line off the booster with the engine running to see if there is vacuum to the booster, this will likely make the engine stall out if the booster is working properly. A little trick I do when bleeding my brakes is take about 16 inches of clear tubing that fits the bleeder, then get a quart Mason jar stick the tubing that is attached to the bleeder into the jar, then add about and inch of brake fluid to the jar and start pumping the petal. Always keep an eye on the jar and your master cylinder as to not let the master cylinder run out, or the jar to overflow. Hope this helps, good luck. If I think of something else I'll do another post.
did you check the brake booster ? how long you use the brake booster? may be have no enough pressure in vacuum brake booster. get more details here for help : http://www.fiverhope.com/ http://www.fiverhope.com/category-67-b0-Brake-booster.html
I had the same problem and replaced both calipers with no change, I figured it was the master cylinder. When I pulled off the master cylinder I saw the vacume booster had about 2 cups of brake fluid in it which leaked from the front of the master cylinder. I replaced master cylinder and vacume booster and brakes work great now.
Eighter you have problem to the to the anti lock brake modelue like a connection .Or there it a stuck valve inside BPMV witch is the molelue likely a dump valve witch is suppose to release the pressure .Unpluging the vacuum hose to the vacuum booster control will just disable the power brakeing mode .Try to figure witch wheel or wheels are not releaseing because the anti lock feature should not come into play unless there are extreame brakeing conduitions .See if its not a problem with a caliper sticking
When you installed new calipers, did you bleed the lines out? Air trapped in the system can cause sticking. Unless they were sticking before you replaced all the parts. Try unplugging the ABS controller under the hood. If that does not work and there is no air in the lines then it would be 1 of 2 things.
1. Master cylinder failing to return. 2. Brake booster not providing enough vacuum.
Start the car. let it run for 10 seconds. while its running pump the brakes. let the brakes go and shut off the car. now press the peddle til it gets stiff. Now hold it down firmly. If the peddle pressure fades, replace the booster.
That sounds like a brake booster problem. The brake booster runs on engine vacuum to help make the brake pedal easier to push and easier to stop the tahoe. When a booster develops an internal leak, you can hear the vacuum escaping through the leak when you step on the brake. The engine stalls because the vacuum leak in the brake booster also causes a large vacuum leak for the engine.
To verify that this is actually the problem, go outside the vehicle with the hood open. Find the large brake fluid reservoir attached to a large round metal black (usually) canister on the driver's side of the firewall. (back of the engine compartment.) There is a large black rubber hose pushed into the top of the black canister, which is the vacuum line attached to the brake booster. Pull the rubber hose out of the grommet on the booster and stick your finger over the hose. Have someone start the tahoe. You will feel a considerable amount of vacuum pulling at your finger, and if you take your finger off the hose, the engine will stall. Also have someone step on the brakes while your finger is over the vacuum hose. If the noise is gone then you know the problem is in the brake booster. Don't forget to re-attach the vacuum line to the brake booster. Failure to do this will result in the engine running very rough (if at all) and the brakes will require excessive effort to try to stop the tahoe.
The booster diaphram has probably failed. Check to see if the vacuum line to the booster is still holding vacuum when the car is turned off. Also check the other end of the hose to make sure it is not leaking where it attaches to the engine intake manifold. With the engine running, stick your head under the dash and press the brake with your hand. Listen for an air leak in the booster, which is in front of the brake pedal, in the engine compartment. If the booster is getting vacuum, but is not boosting, replace the booster. Let us know if you need the procedure or if you have other questions.
You must inspect ALL Brake lines, flexible and steel, and each corner brake. Look for fluid leaks. If everything below is okay, replace the M/C. I suspect damaged cup or bore. do not rebuild, get a new one. Unlikely too much vacuum.