Q: What is the function and maintenance requirements of the hydraulic power brake booster?
A: The hydraulic booster, introduced in 1993 and later models, replaces the vacuum-powered brake booster and utilizes hydraulic pressure from the power steering pump to enhance brake power. It is mounted between the firewall and the Brake Master Cylinder. Normal operating parameters include a hissing noise during heavy braking and clunking or clicking noises when quickly releasing the brake pedal after hard braking. The hydraulic power brake booster requires no special maintenance but certain conditions must be met for proper functioning, such as a good condition drivebelt, correct power steering fluid level, kink-free pressure lines, leak-free booster unit, and an air bubble-free power steering system. Repair of the booster unit necessitates special tools, therefore, it is recommended to install a new or rebuilt unit if a problem arises. The removal process involves disconnecting the master cylinder, ABS control module, and isolation/dump valve, draining power steering fluid, disconnecting the power steering fluid reservoir supply hose and pressure lines, removing the driver's side knee bolster if necessary, disconnecting the pushrod from the brake pedal, and removing the booster unit from the firewall. Installation is the reverse of removal, including tightening the mounting nuts and hose fittings to specified torque, adding power steering fluid, checking for leaks, bleeding the power steering system, and testing the braking system before normal use.