GM 19209269
Master Cylinder

To start replacing the brake master cylinder, use the parking brake and block the wheels. Separate the brake pipes from the master cylinder and cover the bare pipe ends with rubber caps or plugs so brake fluid does not leak out and get contaminated. After blocking the brake pipe openings, loosen the master cylinder nuts and bolts and take it out. Take out all brake fluid from the master cylinder reservoir. Then, you should bleed the master cylinder on the bench and reinstall it into the car. After you install and tighten the master cylinder bolts and nuts to 36 Nm, connect the brake pipes and tighten their nuts to 30 Nm. In the end, bleed the hydraulic brake system.

Start Brake Master Cylinder overhauling by taking out the component from your vehicle and locking the mounting flange in a bench vise to access the rear of the primary Piston. Prepare the reservoir area first then unscrew the cap along with the diaphragm to check for damage that needs replacement. Use the tool to slowly push down on the primary Piston while removing its retainer parts and finally the Piston assembly from the cylinder. Jam all cylinder intake and back outlet holes after hooking front outlet to a filtered hver source that pumps out low pressure air to unravel the secondary Piston with its secondary and primary seals plus return spring. Keep both items for recycling while discarding the main Piston set. Wash the areas inside and outside of the master cylinder as well as the secondary Piston and return spring. Use denatured alcohol for cleaning before inspecting for damage. Replace the master cylinder if you spot cracks, surface issues, or chemical reactions. Dry all parts using filtered air that does not contain lubricant while you apply brake fluid from a sealed container to the master cylinder bore as well as the secondary Piston and return spring. Install the new primary seal and retainer components together with the secondary seal onto the secondary Piston. Also insert the return spring and secondary Piston assembly which you previously lubricated inside the cylinder bore. Put the new lubricated primary Piston assembly into place at the end. Use a flat tool to press down the primary Piston while installing its new retainer before fitting back the master cylinder equipment.

A bench bleeding procedure of the Brake Master Cylinder removes air from the system thus shortening post-installation brake hydraulic bleeding times. Set up the master cylinder by connecting the outlet ports to mounting it onto a vise where the front section rests at a downward angle. Stroke the primary Piston several times using a round-end tool for 25 mm (1 inch) while filling the reservoir with clean brake fluid but recognize that the Piston will not extend its entire length during this process because air exits through the opening. After rearranging the master cylinder within the vise with the front positioned at a slight upward angle repeat the Piston movement process. Following vise positioning with the master cylinder at an even height you should open the outlet ports one by one while pushing the Piston through the bore to remove air. Use the smooth round-end tool to push the Piston home after plugging the outlets before releasing it back from the bore to keep air out. After finishing installation follow standard bleeding methods and finish by re-filling the reservoir with fresh brake fluid.

To start replacing the brake master cylinder, use the parking brake and block the wheels. Separate the brake pipes from the master cylinder and cover the bare pipe ends with rubber caps or plugs so brake fluid does not leak out and get contaminated. After blocking the brake pipe openings, loosen the master cylinder nuts and bolts and take it out. Take out all brake fluid from the master cylinder reservoir. Then, you should bleed the master cylinder on the bench and reinstall it into the car. After you install and tighten the master cylinder bolts and nuts to 36 Nm, connect the brake pipes and tighten their nuts to 30 Nm. In the end, bleed the hydraulic brake system.

Bench bleed the new master cylinder.

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