Vacuum Brake Booster Check Valve: Testing and Inspection

Checking Check Valve

Shown On Model 220:

1 Press the brake pedal several times until the vacuum in the brake booster is reduced
2 Connect tester (030) to brake booster

NOTE: Measuring connection (031) for checking the check valve (17) and/or brake booster (16).

3 Start the engine and produce a vacuum of 0.75 to 0.80 bar by opening the throttle and suddenly releasing the accelerator pedal

NOTE: Reduce vacuum > 0.8 bar by depressing the brake pedal.

4 Switch off engine

NOTE:
- Vacuum must not drop by more than 0.2 bar within 30 seconds.
- Vacuum loss > 0.2 bar, replace vacuum line, if necessary, check brake servo

5 Disconnect tester (030) from brake booster