Power brake booster — check, removal and installation Ford F150
Operating check
1. Depress the brake pedal several times with the engine off and make sure that there is no change in the pedal reserve distance.
2. Depress the pedal and start the engine. If the pedal goes down slightly, operation is normal.
Airtightness check
3. Start the engine and turn it off after one or two minutes. Depress the brake pedal several times slowly. If the pedal goes down farther the first time but gradually rises after the second or third depression, the booster is airtight.
4. Depress the brake pedal while the engine is running, then stop the engine with the pedal depressed. If there is no change in the pedal reserve travel after holding the pedal for 30 seconds, the booster is airtight.
Removal and installation
5. Disassembly of the power unit requires special tools and is not ordinarily performed by the home mechanic. If a problem develops, it’s recommended that a new or factory rebuilt unit be installed.
6. In the engine compartment, remove the nuts attaching the master cylinder to the booster and carefully pull the master cylinder forward until it clears the mounting studs. Be careful not to bend or kink the brake lines. On 4WD models remove the front axle vent tube from the master cylinder to brake booster attachment bolt.
7. Disconnect the vacuum hose from the fitting on the power brake booster and vacuum sensor (see illustration).
.7 Disconnect the vacuum hose (1) from the fitting on the power booster and the booster sensor lead (2) (don’t pull the rubber fittings out of the booster)
8. Remove the brake light switch (see Brake light switch – replacement).
9. Remove the retaining pin and disconnect the pushrod from the brake pedal (see illustration).
.9 Squeeze the tabs and remove the retaining pin
Warning: Discard the pin and obtain a new one for installation.
10. Remove the nuts attaching the booster to the firewall (see illustration).
.10 To detach the power brake booster from the firewall, remove these four nuts
11. Carefully lift the booster unit away from the firewall and out of the engine compartment.
12. To install the booster, place it into position and tighten the retaining nuts to the torque listed in this chapter (see this Chapter’s Specifications). Connect the pushrod to the brake pedal and install the NEW retaining pin.
13. Install the master cylinder. Reconnect the vacuum hose and vacuum sensor.
14. Test the operation of the brakes before placing the vehicle in normal service.