How to Tell If the Brake Booster on a Ford F150 Is Bad?by Dan Ferrell
Your Ford F-150 comes equipped with a power brake system, which includes a booster, vacuum hose and fittings. This system greatly increases the pressure you can apply to the brake pedal when slowing or stopping your pickup. After years of service, though, the vacuum hose connecting the engine to the booster may harden, crack or swell, and finally leak. Also, the booster internal diaphragm may rupture or some other component may wear out and render the unit inoperative. Know the condition of the brake booster in your F-150 now by performing two simple tests at home, without the need to use any tools.
Apply the parking brake in your F-150, but do not touch the brake pedal.
Start and idle the engine in your F-150 without touching the brake pedal.
Let the engine idle for one minute, turn off the ignition and wait for another minute before proceeding on to the next step.
Depress and release the brake pedal several times and pay attention to pedal travel as you step on it. With each application, pedal travel should begin to decrease. This is an indication that the brake booster is receiving vacuum assist from the engine. Go on to the next step. Otherwise, check for a vacuum leak on the booster vacuum hose, on the hose fittings and on the booster itself.
Depress and release the brake pedal several times, until pedal travel remains the same, to make sure the vacuum has been released from the system.
Depress the brake pedal lightly, without pushing too hard, and maintain constant pressure on the pedal. At the same time, start the engine and let it idle. As the engine starts, you should feel the brake pedal moving down slightly towards the floor. This means the power booster is working properly, according to James E. Duffy, in “Modern Automotive Technology.” Otherwise, take your F-150 to an auto shop and have it checked and the booster replaced, if necessary.
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