Brakes - Squeal/Whistle When Releasing Brake Pedal
Date: January 16, 2007Order No.: P-B-43.10/02a
Supersedes: P-B-43.10/02 dated May 30, 2006
Group: 43
Revision History
Revision Date Purpose
a 1/16/07 Applicable Models, Series Production Dates and Part Numbers Updated
- 5/30/06 Initial issue
SUBJECT:
Model171.454/456/473, Up to Series Production 11/2006
Model203.040/052/054/056/061/064/065/076/081/084/087/09
Up to Series Production 11/2006
Model209.356/365/375/376/456/465/475/476, Up to Series Production 11/2006
Squealing / Whistling Noise When Releasing Brake Pedal
If you receive customer reports in the above model vehicles of a squealing or whistling noise emanating from the brake pedal area after releasing the brake pedal, replace the brake booster with a revised part. Reference WIS document AR43.10-P-0350V (Model171) or AR43.10-P-0350P (Model203 and 209).
The whistling noise within the brake booster is the result of air flowing between the operating chamber and vacuum chamber of the booster, caused by increased tolerances. The increased tolerances cause air to flow over an internal edge within the booster creating vortices. These vortices can produce a sound which may be perceived as a whistle.
NOTE:
When ordering parts please ensure to add an index 28 to the part number. For models 203 and 209 the revised part will have a Q-status of Q7 or higher. For model 171 the revised part will have a Q-status of Q3 or higher.
Parts Information