Power Brake Booster
With engine stopped, depress brake pedal 10 times. Start engine while depressing brake pedal. If brake pedal moves inward slightly, booster is functioning properly. If brake pedal does not move inward slightly, check engine vacuum, vacuum hose, check valve, and "O" ring between master cylinder and booster. Also check filter screen of brake booster for dirt clogging. If all okay, replace power brake booster.
To check engine vacuum perform the following procedure.
- Disconnect vacuum hose on brake booster.
- Install vacuum tester 34 3 100 between brake booster and check valve. See Fig 1 .
- Check available vacuum when releasing accelerator, going from an engine speed of 3000 RPM with engine at operating temperature. Minimum value should be up to 5 psi (.35 bar).
- Repeat several times.
- Minimum value with specified idle speed and engine at operating temperature is up to 7 psi (.5 bar).