GM 19209234
Master Cylinder

Prior to changing the Brake Master Cylinder make sure to engage the parking brake and immobilize all wheels. Unplug the electrical connection leading to the Brake Fluid Level Sensor (if present) before removing the upper fender support of the driver side. Put rubber seals over brake pipe fittings before disconnecting master cylinder pipes and stopping open ends. Set the park brake and block the wheels while you disconnect and remove first the master cylinder then the reservoir. Mount the master cylinder reservoir first then perform a bench bleed of the master cylinder unit before fitting it to the car. Thread the master cylinder mounting nuts until they achieve a torque force of 36 nm (27 ft. Lbs.). Push off the rubber seals from your exposed brake pipe fittings and unite the brake lines. Tighten the adapter ends to 25 nm (18 ft. Lbs.). Reinsert the Brake Fluid Level Sensor electrical connector and put back the driver side upper fender support. After that normalize brake fluid flow then let go of the parking brake and free the wheels.

Disconnect the electrical connector from the brake fluid level sensor and install a rubber cap or plug to the exposed brake pipe fitting ends.

Use a smooth, round-ended tool to depress and release the primary piston.

Reattach the master cylinder reservoir and its cap and diaphragm, then install the master cylinder back into the vehicle.

Use denatured alcohol, inspecting for cracks, scoring, pitting, or corrosion, and replace the master cylinder if any issues are found.

Discard the primary piston assembly, piston retainer, and seals from the secondary piston.

Tighten them to 36 N.m (27 lb ft).

First, apply the park brake and block the wheels.

Release the park brake and unblock the wheels.

Reconnect the electrical connector to the brake fluid level sensor.

Install a rubber cap or plug to the exposed brake pipe fitting ends.

Wrap the master cylinder with a clean shop cloth to prevent spills before finally removing it from the vise.

Reconnect the electrical connector to the brake fluid level sensor, bleed the hydraulic brake system, and finally, release the park brake and unblock the wheels.

Until fluid flows freely from the ports without air bubbles.

Clean the area around the reservoir cap.

A smooth, round-ended tool is used to depress and release the primary piston.

Tighten them to 33 Nm (24 ft. lbs.).

Crimp the hose at the master cylinder to prevent fluid leakage.

Secure the mounting flange in a bench vise to access the rear of the primary piston.

Observe the fluid flow from the ports as air is bled from the primary and secondary pistons.

The electrical connector from the brake fluid level sensor and the brake pipes.

Attach transparent hoses to the fittings and route them into the master cylinder reservoir.

Remove the rubber cap or plug from the exposed brake pipe fitting ends, connect the brake pipes, and tighten the fittings to 25 Nm (18 ft. lbs.).

Bench bleed the master cylinder.