Stealth R/T V6-2972cc 3.0L DOHC (1991)
Vacuum Brake Booster: Symptom Related Diagnostic Procedures
Decreasing Brake Pedal Travel
If a decreasing brake pedal is encountered, the power brake unit may be binding internally. To test the power brake unit for this condition proceed as
follows:
1. Place transmission shift lever in Neutral and START engine.
2. Increase engine speed to approximately 1500 rpm, close throttle and completely depress brake pedal.
3. Slowly release brake pedal and stop engine.
4. Remove vacuum check valve and hose from power brake unit. Observe brake pedal for backward movement.
5. If brake pedal moves backward, power brake unit has internal binding, and must be replaced.
Dragging Brakes
If brakes release slowly or incompletely (brakes drag), the power brake unit may be binding internally. To test for an internal bind condition, refer to
Decreasing Brake Pedal Travel.
Hard Brake Pedal
A "hard" brake pedal could be caused by internal binding in the power unit or a failed vacuum check valve. Refer to Decreasing Brake Pedal Travel to
test power brake unit for an internal bind. To check for a failed vacuum check valve, proceed as follows:
1. Start engine and increase engine speed to approximately 1500 rpm, then close throttle and stop engine.
2. Wait 90 seconds, then try brake action.
3. If brakes are not vacuum assisted for two or more applications, replace check valve.
