GM 19432944
Master Cylinder

Start the Brake Master Cylinder replacement process by fixing the mounting flange to a bench vise while keeping the primary Piston rear section within reach. Mount brake fluid hoses to the master cylinder when you add suitable adapters that match the needed flare seat type. Join each port of the Brake Master Cylinder to transparent hoses through its fittings then direct them into the reservoir. Put delco supreme 11(R) brake fluid gm p/n 12377967 or its accepted equivalent from a packaged container into the reservoir until it reaches halfway, while keeping all tubes completely in the fluid. Press and release the primary Piston gently 25 mm using a circular tool while observing clear fluid flow from the ports. Managing air loss relieves pressure on the main Piston. Perform this exercise until the ports deliver clear fluid without trapped air. Push the transparent hoses out of the reservoir and put back its cap and diaphragm before disconnecting fittings with the hoses from the master cylinder ports. Keep the master cylinder covered with clean cloth to avoid spills during the process. Take the master cylinder out of the vise at the end of the process.

You must disable the vehicle ignition before you begin replacing the Brake Master Cylinder (J92). Discard the brake fluid that has been removed from the Brake Master Cylinder reservoir into an approved waste container. Connectors for the Brake Fluid Level Sensor and both supply and return hoses for the master cylinder reservoir require removal before positioning the hoses to the side. Cap the primary brake pipe fitting while you disconnect it to block fluid escape and master cylinder port contamination. Perform the capping and plugging procedure on the left supply brake pipe fitting followed by the right supply brake pipe fitting then right front brake pipe fitting and finally left front brake pipe fitting . Pull out the Brake Master Cylinder nuts and get rid of them before removing the Brake Master Cylinder and the master cylinder seal . During installation you should bench bleed the master cylinder before safely securing the Brake Master Cylinder seal within the adapter while ensuring every part of the seal fully anchors itself into place. Place two new Brake Master Cylinder nuts and torque them to 33 n.m (24 lb ft). Tighten all connections using a torque of 30 n.m (22 lb ft) following installation of left front brake pipe fitting , right front brake pipe fitting , right supply brake pipe fitting and left supply brake pipe fitting and primary brake pipe fitting . Reconnect the Brake Master Cylinder reservoir return hose quick connect followed by the supply hose quick connect and the Brake Fluid Level Sensor electrical connector. Complete reservoir filling and continue with bleeding the hydraulic brake system.