4 Runner 4WD V6-180.5 2959cc 3.0L SOHC (3VZ-E) (1989)
Vacuum Brake Booster: Testing and Inspection
Air Tightness Check
Fig. 3 Piston Stopper Bolt Removal
1.
Start engine and stop after one or two minutes.
2.
Depress brake pedal several times slowly. If pedal drops the most on the first time, but gradually rises after the second or third time, booster is air
tight, Fig. 3.
3.
Depress brake pedal with engine running, then while depressing brake pedal stop engine. If there is no change in pedal reserve travel after holding
pedal for 30 seconds, the booster is air tight.