Some 2004-08 General Motors vehicles (full list below) may emit a squeaking sound when the brake pedal is slowly applied or released. One possible cause for the noise, GM said, is contaminated brake fluid, which will swell the seals in the master cylinder.
To make an accurate diagnosis, have a fellow technician apply and release the brake pedal while you listen for the squeak under the hood. If you can isolate the squeaking noise to the master cylinder area, contaminated brake fluid is the likely cause.
Draining the master cylinder and flushing the brake system with a new DOT 3 brake fluid, Part No. 88862806, should put an end to the trouble.
Vehicles that are susceptible to the trouble include 2004-07 Buick Rainiers; 2008 Buick Enclaves; 2004-08 Chevy Colorado, TrailBlazer, TrailBlazer EXT and TrailBlazer SS models; 2008 Chevy Malibus; 2004-08 GMC Canyons, Envoys, Envoy XLs and Envoy XUVs; 2007-08 GMC Acadias; and 2008 Pontiac G6s.
"Factory Fixes" is written by Jim DePalma, a 30-plus-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected].
Be on the lookout for Tire Business' new 5 Factory Fixes newsletter, publishing the first Friday of each month.