Expedition 2WD V8-5.4L SOHC VIN L (1997)
Vacuum Brake Booster Check Valve: Description and Operation
Power Brake System Components
The power brake booster check valve:
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Is located on the front of the power brake booster.
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Is positioned between the power brake booster and the power brake booster hose.
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Closes when the engine is turned off.
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Is part of the power brake booster, and is not replaced separately.
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In the closed position, traps engine vacuum in the power brake booster.
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Reserves vacuum and allows several power assisted brake applications with the engine off.
