OEM 2003 Chevrolet Astro Brake Master Cylinder

2003 Chevrolet Astro Brake Master Cylinder Parts Questions & Experts Answers

• Q: How to overhaul the brake master cylinder on 2003 Chevrolet Astro?

  A: To overhaul the Brake Master Cylinder, take it off the vehicle and mount its mounting flange in a bench vise, and make sure the rear of the primary Piston is visible. Clean the environs of the cap of the reservoir before taking them off together with the diaphragm checking them for cuts, cracks, nicks or deformation, and replace in case of damaged parts. Then, unbolt the master cylinder reservoir, then insert a smoothly rounded tool and push primary Piston and remove Piston retainer, the primary Piston assembly then coming out of the cylinder bore. Plug the cylinder inlet ports and rear outlet port, fill the front outlet port with low-speed, non-lubricated and filtered air to purge the secondary Piston with primary and secondary seals and the return spring, discarding the assembly primary Piston, Piston retainer, and the seal. To assemble, clean the interior and exterior of the master cylinder, secondary Piston,and return spring with denatured alcohol, looking for any cracks, scoring, pitting, or corrosion, and replacing the master cylinder if problems are evidence. Dry all components with non- lubricated, filtered air, then lubricate master cylinder bore, secondary Piston, return spring and all overhaul components with brake fluid, delco supreme ii, gm p/n 12377967 (Canadian p/n 992667) or equivalent dot-3. Mount the new primary seal and the new retainer, as well as the new secondary seal onto the secondary Piston, and then place the lubricated return spring and secondary Piston assembly into the cylinder bore, followed by the lubricated new primary Piston assembly. Depress the primary Piston with a smooth round ended tool to be able to install in the new Piston retainer, and replace the master cylinder reservoir and it's cap and diaphragm in order to reattach it and the master cylinder to the vehicle.