GM 19209236
Master Cylinder

Start Brake Master Cylinder repairs by placing the mounting flange in a bench vise to work on the back of the main Piston. Fit suitable adaptors into both master cylinder ports with flare seat hoses ready for connection. Install these adaptors at the master cylinder ports to accept the necessary hoses. Feed transparent hoses into the reservoir after you attach them to the master cylinder end fittings. Add brake fluid until the delco supreme 11 supply tank (GM P/N 12377967, Canadian P/N 992667) or its equivalent dot-3 brake fluid reaches at least its midpoint. Maintain the hose ends inside the fluid while filling. Depress and release the primary Piston 25 mm using a smooth tool until fluid flows from ports and you notice increased depression force and reduced travel in the Piston due to air extraction. Push down on the Piston while checking for liquid flow until the ports release fluid without air inclusions. Reposition the transparent hoses back into the reservoir before putting back the master cylinder diaphragm and reservoir cap. Finally free the fittings from each master cylinder port while keeping the master cylinder wrapped in a clean cloth to avoid spills.

When working on the Brake Master Cylinder vacuum support you must first activate the parking brake and secure all wheels. Pull out the electrical connection from the brake fluid sensor and pipes from the master cylinder before putting rubber caps on the brake pipe ends to avoid fluid loss and contamination. To remove the system take out the master cylinder by unscrewing the mounting nuts plus extracting the reservoir. Begin by installing the master cylinder reservoir and proceed with master cylinder bleeding on a working surface. If the seal has damage replace it with a new one matching its proper placement against the master cylinder base. Reinstall the master cylinder into its vehicle location then bolt it down with the mounting nuts until they reach 36 nm (27 ft. Lbs.). Join the brake pipes by removing their rubber caps and tightly fasten the fittings with 25 nm torque. Connecting the sensor electrical wires then bleeding the brake system allows you to free the park brake and unblock the wheels.

You can service the Brake Master Cylinder by placing its mounting flange in a bench vise while having easy access to the primary Piston cavity. Put the master cylinder reservoir diaphragm aside and install suitable fittings to the master cylinder ports to connect hoses. Join clear tubes to these ports and feed them into the brake fluid storage space. Submerge the brake fluid hoses ends deep into a clean sealed container of delco supreme 11 brake fluid before pouring at least half of the reservoir capacity to match. Press the primary Piston of the tool every 25 mm (one inch) into action and watch the fluid exit the ports using a round shaped smooth implement. Depressing the primary Piston becomes harder and its downward travel narrows as you bleed the air out of both Piston chambers. Perform this stage of bleeding until the valves release fluid without creating air bubbles. Replace transparent hoses in the reservoir then put on the diaphragm and reservoir cap. Next take off fittings with hoses from ports before leaving the master cylinder in the cloth and removing it from the vise.

Wheels should be blocked by applying the park brake before replacing the Brake Master Cylinder (Hydraulic Boost). First disconnect the electrical connector from the Brake Fluid Level Sensor. Then apply rubber caps or plugs to stop brake fluid from leaking out and contaminating the brake pipe fitting ends before taking the brake pipes off the master cylinder. The process starts with plugging open brake pipe ends then removing the master cylinder mounting nuts to completely remove the master cylinder and its reservoir from the vehicle. Begin the installation process with the master cylinder reservoir followed by bench bleaching the master cylinder before reinstalling the vehicle. Follow by mounting the master cylinder with its nuts then torque them to 33 nm (24 ft. Lbs.). Begin by removing the rubber plugs or caps from the open brake pipe ends before you insert and tighten the brake pipes to 25 nm (18 ft. Lbs.). The electrical connector leads to the Brake Fluid Level Sensor at this point followed by hydraulic brake system bleaching through the lines before releasing the park brake and unblocking wheels.

To fix the Brake Master Cylinder start by fastening its mounting flange in a bench vise to reach its rear. Secure fittings near the master cylinder ports for flare seating that can connect to hoses and remove the diaphragm and reservoir cap. Insert transparent hoses to these fittings then guide them into the master cylinder reservoir. Pour delco supreme ii brake fluid (GM P/N 12377967 or equivalent DOT-3 brake fluid) into the master cylinder reservoir until the liquid reaches half its volume through hose ends that must be completely dipped into the fluid. Press the primary Piston down 25mm using a rounded tool and let it return to its starting position until the fluid flows smoothly across ports. Pressing the primary Piston will become harder and its travel shorter as it pushes air out of the system. Maintain this procedure until brake fluid emerges fully from the openings without air content. Put the master cylinder reservoir back on then connect the end fittings to port openings before taking the master cylinder out from the vise.

Dry all components with non-lubricated, filtered air.

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

Remove the transparent hoses from the reservoir, reinstall the master cylinder reservoir cap and diaphragm, and then remove the fittings with the hoses from the ports.

Remove the master cylinder mounting nuts and take the master cylinder out of the vehicle.

Apply the park brake and block the wheels.