OEM 2004 Buick Rainier Brake Master Cylinder

2004 Buick Rainier Parts Questions & Experts Answers

• Q: How to service and repair the Brake Master Cylinder on 2004 Buick Rainier?

  A: First, hold the mounting flange in a bench vise to make sure you can easily get to the rear of the primary Piston. Take off the reservoir cap and diaphragm from the master cylinder, and afterwards screw in fittings to the ports so you can connect hoses. Put transparent hoses onto these fittings and feed them into the reservoir. Be sure the reservoir is filled to at least halfway with delco supreme 11 or another dot-3 brake fluid, using a sealed and clean container, and make certain the hose with a smooth, round-ended tool, move the primary Piston down about 1 inch (25 mm) a couple of times and see how the fluid flows from the ports. You will feel that it takes more effort to push the primary Piston as the air gets bled, while the travel distance gets shorter. Continue to do this until all air bubbles are out and fluid starts flowing easily from the ports. Once this is done, uncouple the clear hoses from inside the reservoir, put on the master cylinder cap and diaphragm, then twist off the fittings from the ports, and wrap the master cylinder with a shop cloth before pulling it out of the vise.