Vacuum Brake Booster: Testing and Inspection

OUTPUT ROD LENGTH CHECK





1. Apply vacuum of 66.7 kPa (500 mm Hg, 19.69 in Hg) to brake booster with a hand vacuum pump.
2. Check output rod length.
3. Specified length: 10.275-10.525 mm (0.4045-0.4144 inches)

OPERATING CHECK
^ Depress brake pedal several times with engine off. After exhausting vacuum, make sure there is no change in pedal stroke.
^ Depress brake pedal, then start engine. If pedal goes down slightly, operation is normal.

AIRTIGHT CHECK





^ Start engine, and stop it after one or two minutes. Depress brake pedal several times slowly. Booster is airtight if pedal stroke is less each time.
^ Depress brake pedal while engine is running, and stop engine with pedal depressed. The pedal stroke should not change after holding pedal down 30 seconds.