B3000 SE Regular Cab 4WD V6-3.0L OHV (1998)
Vacuum Brake Booster Check Valve: Testing and Inspection
INSPECTION
The function of the check valve is to allow manifold vacuum to enter the power brake unit and prevent the escape of vacuum in case manifold vacuum
is lost during sustained full throttle operation.
To test the check valve:
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Start and run the engine for at least 10 seconds.
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Operate the brake pedal to check for power assist.
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Disconnect the vacuum hose from the power brake unit. Do not remove the check valve from the power brake unit.
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There should be enough vacuum retained in the power brake unit for at least one more power assisted brake operation.
