Title: Inspect vacuum-type power booster unit for leaks; inspect the check-valve for proper operation; determine needed action.
Course: Automotive Technology III (20104-III) > Section: Brakes: Power-Assist Units Diagnosis and Repair

Inspection should include

- listening for noise (e.g., hissing, air leaks)
- depressing brake pedal and releasing
- checking reserve
- restarting engine.

ASE Education Foundation
2017 Automobile Service Technology (AST) Level
V. Brakes
E. Power-Assist Units Diagnosis and Repair
Task 1

Process/Skill Questions:

- How does a vacuum booster operate?
- What are the procedures to inspect and check the operation of a vacuum booster?
- What is the operation of the check valve and vacuum valve?