OEM 2003 GMC Envoy Brake Master Cylinder

2003 GMC Envoy Brake Master Cylinder Parts and Q&A

• Q: How to service and repair the Brake Master Cylinder on 2003 GMC Envoy?

  A: Begin repairs on the Brake Master Cylinder by placing its mounting flange in a bench vise to locate the primary Piston at the back. Install correct fittings on master cylinder ports that match necessary flared-seam standards and enable hose connections. Place these fittings on master cylinder ports and join them with transparent hoses into the reservoir. Place delco supreme 11 gm brake fluid reference numbers 12377967 and 992667 or equivalent dot-3 brake fluid in the reservoir until it reaches halfway while completely immersing hose ends in a clean sealed fluid container. Depress the primary Piston into a cylinder 25 mm using a smooth blunt instrument and watch fluid flow from both ports. You will notice air exits the primary and secondary pistons during the process as pushing force grows stronger and depression distance shortens. Push and release the primary Piston again to know fluid flows out of ports without trapped air. Replace the transparent hoses in the reservoir. Put back the master cylinder reservoir parts and take off the fittings with hoses from the provider ports. Soften spills during removal with shop cloth before taking the master cylinder out of the vise.