Park Avenue V6-3.8L VIN K (1995)
Vacuum Brake Booster Check Valve: Technical Service Bulletins
Interior - Metallic Buzz/Rattle From I/P, Brakes Applied
File In Section: 5 - Brakes
Bulletin No.: 73-50-19
Date: May, 1997
Subject:
Metallic Buzz/Rattle Noise from Instrument Panel Area with Brake Pedal Depressed (Install a Revised Check Valve)
Models:
1995-97 Buick LeSabre, Park Avenue, Riviera
1995-97 Cadillac Concours, DeVille, Eldorado, Seville
1995-96 Oldsmobile Ninety Eight
1995-97 Oldsmobile Aurora, Eighty Eight
1996-97 Oldsmobile LSS
1997 Oldsmobile Regency
1995-97 Pontiac Bonneville
Condition
Some owners may comment on a metallic buzz or rattle type noise when the brake pedal is depressed. This noise may seem to come from the instrument
panel cluster area and has been described as sounding like an ABS system self-test or speedometer cable type sound. Brake pedal force and engine load
may affect the ability to reproduce the sound.
Cause
The cause of this noise may be the brake booster vacuum check valve resonating in response to engine vacuum pulsations.
Correction
A revised check valve, P/N 18029764, is available to correct this condition.
Diagnose and repair brake booster check valve noise as follows:
1.
Determine the brake pedal force and engine throttle load needed to reproduce the noise. Also, determine if the transmission must be in drive range
instead of park position.
Important:
There is no power brake assist available when the vacuum check valve is separated from the brake booster.
2.
Remove the brake booster check valve and seal the valve with tape to prevent a vacuum leak.
3.
If the noise can only be reproduced in drive range, then block the wheels to prevent vehicle movement.
4.
Attempt to reproduce the booster check valve noise. If the noise is gone, replace the check valve with revised P/N 18029764. If the noise persists,
then check for other conditions that can cause the noise such as grounded out powertrain components.
Parts Information
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
Labor Time
Use published labor
H1240
operation time.
