Check Valve

The function of the brake booster check valve is to allow manifold vacuum to enter the power brake booster and prevent the escape of vacuum if the manifold vacuum is lost during sustained full-throttle operation.

To test the function of the power brake booster check valve:

• Start and run the engine for at least 10 seconds.
• Operate the brake pedal to check for power assist.
• Disconnect the vacuum booster hose from the brake booster. Do not remove the brake booster check valve from the brake booster.
• There should be enough vacuum retained in the brake booster for at least one more power-assisted brake operation.