OEM 2004 Buick LeSabre Brake Master Cylinder

2004 Buick LeSabre Brake Master Cylinder Parts Questions & Experts Answers

• Q: How to overhaul the brake master cylinder on 2004 Buick LeSabre?

  A: Begin Brake Master Cylinder overhaul by removing the device from the vehicle to secure its mounting flange in a bench vise with access to the rear of the primary Piston. First clean the reservoir's outside area near the cap then remove the components to check for damages before performing replacement of defective parts. A smooth round-ended tool should be used to depress the primary Piston before extracting the Piston retainer and primary Piston assembly. The front outlet and rear outlet ports should be plugged while applying low-pressure filtered non-lubricated air into the front port to extract the primary Piston assembly along with the primary and secondary seals and return spring. Discard all the extracted components before resuming. The master cylinder interior and exterior and the secondary Piston and return spring should be cleaned with denatured alcohol while inspecting for cracks as well as scoring pitting and corrosion before replacement if issues are detected. Apply non-lubricated filtered air to dry all components afterward lubing the master cylinder bore with secondary Piston and return spring and overhaul components with delco supreme 11 brake fluid gm p/n 12377967 (Canadian P/N 992667) from clean sealed containers. The new primary seal and retainer should be assembled to the secondary Piston while adding the new secondary seal. Then, the lubricated return spring and secondary Piston assembly should be installed into the cylinder bore to which the lubricated new primary Piston assembly should follow. Use a round-ended smooth tool to press down the primary Piston as you put on the new Piston retainer and reinstall both the master cylinder reservoir and its cap and diaphragm. Reinstall the master cylinder as the last step.