Brakes - Whistling Noise When Pressing Brake Pedal
Date: November 30, 2004Order No.: P-B-42.46/32b
Supersedes: P-B-42.46/32a dated January 16, 2004
Group: 42
Revision:
Updated Applicable Models and Added Production Range
SUBJECT:
Models 211.026/065/070/076/082/083/265/282/283, up to Production Date 08/02/2004
Whistling Noise When Depressing the Brake Pedal
If you receive customer reports in the above model vehicles of a high frequency (4kHz) whistling noise anytime the brake pedal is depressed and the noise continues until the brake pedal is released, please perform the below mentioned procedure to resolve.
The noise is generated by the separation valve coils in the SBC hydraulic control unit. The whistling noise is conducted via the hydraulic brake lines from the SBC hydraulic control unit (HCU) to the brake operating unit (BOU) and then into the interior of the vehicle. This noise occurs during each operation of the brake pedal and persists as long as the brake pedal is depressed. Do not confuse this noise with pressure build up or pressure reduction noise that can be heard briefly when the brake pedal is being depressed or released.
To resolve, replace the existing steel lines with the two flex lines (HZ1 and HZ2) and return line to decouple the whistling noise. When routing the new lines, ensure that the new lines do not touch each other or any other components, and are not installed under tension or are twisted.
Note:
Failure to closely observe these instructions will prevent successful remedy of the complaint. This remedy is exclusively intended to eliminate the above mentioned high frequency (4kHz) whistling noise, no other noises can be eliminated by installing these flex lines.
Parts Information
Note:
The following allowable labor operations should be used when submitting a warranty claim for this repair.
In Case of Warranty, use the table.