GM 19209250
Master Cylinder

The service work on the Brake Master Cylinder with vacuum boost starts by putting on the parking brake and blocking the wheels. Drop the brake fluid reservoir level sensor electrical connector then detach the brake pipes from the master cylinder unit while using rubber plugs to seal the exposed ends of the pipes. First close the brake pipes then remove the master cylinder mounting nuts and pull out the master cylinder assembly from the vehicle followed by the reservoir. Begin by fitting the master cylinder reservoir and blee the master cylinder on a workbench before reinstalling it to the vehicle system. Fasten the master cylinder mounting nuts to their proper bolt torque value of 36 nm (27 ft. Lbs.). Seal the brake pipe end flange with the rubber cap and join the brake hoses then secure them at 25 nm (18 ft. Lbs.). Connect the brake sensor's electrical connector and perform hydraulic brake bleeding then let go the parking brake and remove blockages.

First block all wheels and apply the park brake when replacing the Brake Master Cylinder (Hydraulic Boost). Install rubber caps or plugs on the exposed brake pipe fitting ends after you disconnect the Brake Fluid Level Sensor electrical connector to avoid brake fluid loss and contamination. The first step is to cover exposed brake pipe ends before unmounting the master cylinder with its mounting nuts then extracting it from the vehicle before removing the master cylinder reservoir. Bleed the master cylinder during installation by first mounting the reservoir while bench bleeding followed by a return to the vehicle. Once installed tighten the master cylinder mounting nuts to 36 nm (27 ft. Lbs.). After removing the rubber cap or plug from the brake pipe fitting ends which were exposed. Tighten the pipe fittings between 25 nm to 18 ft. Lbs.connect the electrical connector back to the Brake Fluid Level Sensor. After bleeding the hydraulic brake system the mechanic should release the park brake and unblock the wheels.

You need to activate the parking brake and eliminate the electrical link to the brake fluid sensor prior to installing a hydraulic Brake Booster and a new Brake Master Cylinder. To prevent brake fluids from leaking or being contaminated seal the brake pipes before removing them from the system. Lift off the master cylinder nuts before taking out the master cylinder parts plus its reservoir. Begin setup by attaching the master cylinder reservoir first before bleeding the unit on the bench. Install the master cylinder by hand and secure its mounting nuts to 36 n.m (27 lb ft). Reconnect the brake pipes by installing them into their fittings before tightening to 18 lb ft (25 N.m). Rejoin the electrical sensor then bleed the brake system before letting go of the parking brake.

Reconnect the electrical connection at the brake fluid level sensor, bleed the brakes, and finally release the parking brake.

Install the master cylinder, ensuring to tighten the mounting nuts to 36 N.m (27 lb ft).

Plug the cylinder inlet ports and the rear outlet port.

Apply the parking brake and disconnect the electrical connection at the brake fluid level sensor.

Remove the master cylinder brake fluid reservoir.

Clean the outside of the master cylinder reservoir around the cap.

Install the master cylinder reservoir and bench bleed the master cylinder before installing it.

Install suitable fittings to the master cylinder ports for hose attachment.