Grand Marquis V8-255 4.2L (1982)
Hydraulic Brake Booster: Service and Repair
Hydro-Boost
1.
Working under instrument panel, disconnect stop light switch wires at connector. Remove hairpin retainer. Slide switch off brake pedal pin just far
enough for switch outer hole to clear pin. Then lift switch straight upward from pin. Slide master cylinder pushrod and nylon washers and bushing
off brake pedal pin.
2.
Open hood and disconnect brake line at master cylinder outlet fitting.
3.
Disconnect the pressure, steering gear and return lines, then plug lines and ports.
4.
Remove Hydro-Boost to dash panel nuts and remove assembly from panel, sliding pushrod link from engine side of dash panel.
5.
Reverse procedure to install. To purge system, disconnect coil wire so that engine will not start. Fill power steering pump reservoir, then while
engaging starter, pump brake pedal. Do not cycle steering wheel until all residual air has been purged from the hydro boost unit. Check fluid level,
then connect coil wire and start engine. Apply brakes with a pumping action and cycle steering wheel, then check system for leaks.
