How to Bleed Car Brakes

If air gets trapped in the brake lines because of leaks or replacement of parts, it will make the pedal spongy and lessen the force of the linings pressed against the discs or drums. It is important to force the air out through bleed valves at every wheel.

If the car has power brakes, turnoff the engine and start by pumping brake pedal ten times, this will use any vacuum present in the booster. Now the car has to be raised and a length of clean vacuum hose has to be attached to one of the bleed valves. The other end of the hose has to be inserted into a partly filled jar of fresh brake fluid. A wrench can be used to open the valve, it should be three quarters of a turn. Take help from someone to apply the brakes steadily and slowly. Once the pedal reached the floor, the valve has to be closed. Then the helping person should slowly return the pedal to its original position. This procedure has to be repeated until the air bubbles stop coming out from the hose. Fresh brake fluid should be continued to be added into the reservoir so it does not become dry. Bleed each wheel until old fluid runs clear, this is for replacing all the fluid in the system.

Bleed Car Brakes

Some drum or disc systems have a metering system under the master cylinder that may become a cause of preventing fluid from being pumped out of the front disc brakes. This case might require you to hold open the metering valve.

Once the bleeding of brakes has been completed, the brake warning light will lit up. For turning it out in late car models, the ignition switch has to be turned to the ON or accessory position and brakes have to be applied at once.

Warning light switch present on old cars has to be replaced with special stud. An auto dealer can be consulted if your car requires one. Any dust cap present should be removed and the bleed valve has to be cleaned. It is present on the backing plate of the drum brakes. They are also found on disc brake calipers. The box wrench has to be placed over the valve and then the hose has to be forced. The helper can used to pump the brakes until the bubbles are no more or the dark fluid has been displaced, the hose should be kept submerged.

On old cars, the switch inside the metering valve housing must be centered for shutting off the light. For doing this, the bleed valve in the opposite circuit of the last bled valve has to be opened. The helper can slowly press the brake pedal until the light turns off. Ten the bleed valve has to be closed immediately. If the light turns on again, this means that the center of the switch has been overshot and the procedure must be repeated at the car’s opposite end. This boring procedure can be avoided by replacing the light switch with a small threaded stud before the braked are bled. In case of a 1974 or earlier model of American Motors, the brake warning light switch has to be unscrewed from the metering valve before starting the task. Then it can be replaced when through.

Before the car is driven, the engine has to be started and the brakes have to be pumped to test the firmness of the pedal.

If air gets trapped in the brake lines because of leaks or replacement of parts, it will make the pedal spongy and lessen the force of the linings pressed against the discs or drums. It is important to force the air out through bleed valves at every wheel.

If the car has power brakes, turnoff the engine and start by pumping brake pedal ten times, this will use any vacuum present in the booster. Now the car has to be raised and a length of clean vacuum hose has to be attached to one of the bleed valves. The other end of the hose has to be inserted into a partly filled jar of fresh brake fluid. A wrench can be used to open the valve, it should be three quarters of a turn. Take help from someone to apply the brakes steadily and slowly. Once the pedal reached the floor, the valve has to be closed. Then the helping person should slowly return the pedal to its original position. This procedure has to be repeated until the air bubbles stop coming out from the hose. Fresh brake fluid should be continued to be added into the reservoir so it does not become dry. Bleed each wheel until old fluid runs clear, this is for replacing all the fluid in the system.

Some drum or disc systems have a metering system under the master cylinder that may become a cause of preventing fluid from being pumped out of the front disc brakes. This case might require you to hold open the metering valve.

Once the bleeding of brakes has been completed, the brake warning light will lit up. For turning it out in late car models, the ignition switch has to be turned to the ON or accessory position and brakes have to be applied at once.

Warning light switch present on old cars has to be replaced with special stud. An auto dealer can be consulted if your car requires one. Any dust cap present should be removed and the bleed valve has to be cleaned. It is present on the backing plate of the drum brakes. They are also found on disc brake calipers. The box wrench has to be placed over the valve and then the hose has to be forced. The helper can used to pump the brakes until the bubbles are no more or the dark fluid has been displaced, the hose should be kept submerged.

On old cars, the switch inside the metering valve housing must be centered for shutting off the light. For doing this, the bleed valve in the opposite circuit of the last bled valve has to be opened. The helper can slowly press the brake pedal until the light turns off. Ten the bleed valve has to be closed immediately. If the light turns on again, this means that the center of the switch has been overshot and the procedure must be repeated at the car’s opposite end. This boring procedure can be avoided by replacing the light switch with a small threaded stud before the braked are bled. In case of a 1974 or earlier model of American Motors, the brake warning light switch has to be unscrewed from the metering valve before starting the task. Then it can be replaced when through.

Before the car is driven, the engine has to be started and the brakes have to be pumped to test the firmness of the pedal.