OEM GMC Envoy Brake Master Cylinder

GMC Envoy Brake Master Cylinder Parts and Q&A

• Master Cylinder
  15142479
  Q: How to remove and replace the brake master cylinder on GMC Envoy?

  A:

  Before servicing the Brake Master Cylinder always keep safety in mind by knowing about brake fluid reactions and its effects on brake fluid and electrical systems. Start work by removing the Brake Master Cylinder from the vehicle. Clamp the mounting flange into a workshop vise to let you access the back of the main brake Piston. Before beginning work clean the space near the reservoir cap and remove both components together with the diaphragm. Check for damage on the reservoir cap and diaphragm before replacing them with new parts. You should disconnect the master cylinder reservoir next. With a smooth round tip depress the primary Piston and take off the Piston retainer. Then remove the primary Piston components. Insert air filters into all ports on the cylinder while supplying filtered low-pressure air through the front outlet to push out both secondary and primary components with their return spring. Throw away the primary Piston parts together with the Piston retainer and seals. Clean and examine the master cylinder, return spring and secondary Piston using denatured alcohol alongside maintaining a visual check for damage or wear. If damage is present completely replace the master cylinder. Place wet components in compressed non-lubing filtered air and add delco supreme 11 lubricant into the master cylinder initially with secondary Piston and return spring before fitting all new parts. Place new primary and secondary seals together with the retainer onto the secondary Piston. Add the lubricated return spring and secondary Piston assembly into the cylinder bore. Fit and secure the new lubricated primary Piston assembly into its place with the Piston retainer. Put back the cylinder reservoir before attaching its cap and diaphragm then put back the entire master cylinder system.
• Master Cylinder
  19209266
  Q: How to overhaul the brake master cylinder on GMC Envoy?

  A:

  Before working on a Brake Master Cylinder you must remove it from the vehicle and get the mounting flange into a bench vise where you need access to the rear part of the primary Piston. Prior to removing the cap and diaphragm from the master cylinder reservoir's outside you should clean it thoroughly to check for cuts or cracks or nicks or deformities and replace damaged parts as needed. Start by disconnecting the master cylinder reservoir before using a smooth tool with round ends to push down the primary Piston and then remove the Piston retainer followed by the primary Piston assembly from the cylinder bore. Use low pressure filtered air to blow through the front outlet port while plugging all cylinder inlet ports and the rear outlet port in order to remove the secondary Piston along with its primary Piston and secondary seals and return spring. Keep the primary Piston components for discard. Denoaturred alcohol cleans and inspects the master cylider and secondary Piston and return spring for cracks pitting scoring or corrosion before master cylinder replacement. The bore as well as the secondary Piston and return spring and all overhaul parts require application of delco supreme 11, gm U.S. P/N 12377967, gm canada P/N 992667, or equivalent dot-3 brake fluid from a clean, sealed container after drying the components with non-lubricated, filtered air. Position the new primary seal with the retainer component to the secondary Piston before you install the lubricated return spring and secondary Piston assembly into the cylinder bore then add the lubricated new primary Piston assembly . Use a round-ended tool to depress the primary Piston which installs the new Piston retainer before you reconnect the master cylinder reservoir and its cap and diaphragm. The completion of the installation process involves putting the master cylinder into its original position on the vehicle.