F 350 4WD Pickup V8-351 5.8L VIN H EFI (1997)
Vacuum Brake Booster Check Valve: Testing and Inspection
The function of the power brake booster check valve is to allow manifold vacuum to enter the power brake booster and prevent the escape of vacuum in
case manifold vacuum is lost during sustained full throttle operation. To test the functioning of the power brake booster check valve, perform the
following:
1. Start and run the engine for at least 10 seconds.
2. Operate the brake pedal to check for power assist.
3. Disconnect the vacuum booster hose from the power brake booster. There should be enough vacuum retained in the power brake booster for at
least one more power-assisted brake operation.
