When I try to brake, the pedal barely moves and is hard. I am unable to stop. We bled the brakes and that did not help, then we replaced the front brake pads and that did not help. The rear brakes are new. Could it be the booster or master cylinder?
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Re-calibrate your brake calipers by lifting your caliper housing and using a c clamp to push the caliper back into the housing. DO NOT TAKE THE CAP OFF OF THE BRAKE FLUID RESIVOIR AS THIS COULD LET MORE AIR INTO THE LINES. After you have reset the calipers, try resetting your brakes as before; pump brake pedal until it gives good resistance. With your foot still depressing the brake pedal, start the vehicle. If it does it again, then you may need to re-check where you bled your lines for integrity.
Functional test: 1. With the engine stopped, Depress the brake pedal several times, then depress the pedal hard and hold that pressure for 15 seconds. If the pedal sinks, the master cylinder, brake line or a brake caliper is faulty 2. Start the engine with the pedal depressed. If the pedal sinks slightly, the vacuum booster is working. If the pedal height does not vary, the booster or the check valve is faulty
Leak Test: 1. Depress the brake pedal with the engine running then stop the engine. If the pedal height does not vary while depressed for 30 seconds, the vacuum booster is OK. If the pedal rises, the booster is faulty 2. With the engine stopped, depress the brake pedal several times using normal pressure. When the pedal is first depressed, it should be low. On consecutive applications, the pedal height should gradually rise. If the pedal position does not vary, check the booster check valve.
Check valve test: 1. Disconnect the brake booster vacuum hose at the booster. 2. Start the engine and let it idle. There should be a vacuum available. If no vacuum is available, the check valve is not working correctly. Replace the check valve and retest.
try getting the air in the brakes bled, if that doesnt work check the master cylinder,or when you drive see if when u put on the brakes see if you let go of the sterring wheel and brake to see what side it pulls to,
Hi, your proportioning valve is stuck. Take the caps off and recenter the one stuck valve. Then rebleed the system using the procedure below. Thanks for using fixya.
For those of us who are not fortunate enough to have access to a power bleeding tool, the manual brake bleeding procedure will quite adequately remove air from the hydraulic system. The major difference between the pressure and manual bleeding procedures is that the manual method takes more time and will require help from an assistant. One person must depress the brake pedal, while another opens and closes the bleeder screws.
Deplete the vacuum reserve by applying the brakes several times with the ignition OFF .
Clean the top of the master cylinder, remove the cover and fill the reservoirs with clean fluid.
The master cylinder must be bled first if it is suspected to contain air. If the master cylinder was removed and bench bled before installation it must still be bled, but it should take less time and effort. Bleed the master cylinder as follows:
Position a container under the master cylinder to catch the brake fluid.
Loosen the front brake line(s) at the master cylinder and allow the fluid to flow from the front port.
Do not allow brake fluid to spill on or come in contact with the vehicle's finish as it will remove the paint. In case of a spill, immediately flush the area with water.
Tighten the line connection(s).
Have an assistant depress and hold the brake pedal.
Loosen the line connection(s) again, allowing air to escape from the master cylinder.
Tighten the line(s), then have the assistant release the brake pedal and wait for 15 seconds.
Repeat steps D through F until the line(s) are free of air.
When finished bleeding the air from the master cylinder, tighten the line connections to 20 ft. lbs. (27 Nm).
Repeat steps B through H, only with the master cylinder rear pipe fitting(s).
Refill the master cylinder with fresh brake fluid.
Never reuse brake fluid that has been bled from the system.
If a single line or fitting was the only hydraulic line disconnected, then only the caliper(s) or wheel cylinder(s) affected by that line must be bled. If the master cylinder required bleeding, then all calipers and wheel cylinders must be bled in the proper sequence:
Bleed the individual calipers or wheel cylinders as follows:
Place a suitable wrench over the bleeder screw and attach a clear plastic hose over the screw end. Be sure the hose is seated snugly on the screw or you may be squirted with brake fluid.
Submerge the other end of the tube in a transparent container of clean brake fluid.
With the help of an assistant, apply the brake pedal slowly and hold.
During the bleeding procedure, make sure your assistant does NOT release the brake pedal while a fitting is loosened or while a bleeder screw is opening. Air will be drawn back into the system.
While the assistant continues to apply pressure to the brake pedal, loosen the bleeder screw, and watch for air bubbles in the container.
Be very careful when loosening the wheel cylinder and brake caliper bleeding screws. The bleeder screws often rust in position and may easily break off if forced. To help prevent the possibility of breaking a bleeder screw, spray it with some penetrating oil before attempting to loosen it. Installing a new bleeder screw will often require removal of the component and may include overhaul or replacement of the wheel cylinder/caliper.
Tighten the bleeder screw.
Instruct the assistant to release the brake pedal.
Wait approximately 15 seconds, and instruct the assistant to depress the brake pedal again.
Remember, if the reservoir is allowed to empty of fluid during the procedure, air will be drawn into the system and the bleeding procedure must be restarted at the master cylinder assembly.
Repeat steps C through F until there are no air bubbles present in the container.
Check the pedal for a hard feeling with the engine not running. If the pedal is soft, repeat the bleeding procedure until a firm pedal is obtained.
If the brake warning light is on, depress the brake pedal firmly. If there is no air in the system, the light will go out.
Once all the air is bled from the system, install the bleeder screw caps.
After bleeding, make sure that a firm pedal is achieved before attempting to move the vehicle.