CAUTION: Master cylinder is used to create a seal for holding vacuum in the power brake booster. Vacuum in power brake booster must be released before removing master cylinder. Ensure area around master cylinder filler tube, master cylinder fluid reservoir and master cylinder-to-power brake booster are clean before servicing master cylinder. Area may be cleaned with brake parts cleaner.
Release vacuum from power brake booster by pumping brake pedal several times with engine off until brake pedal becomes firm. Clean area around master cylinder filler tube and master cylinder fluid reservoir.
Remove master cylinder filler tube from master cylinder fluid reservoir by pushing filler tube downward and rotating filler tube. Remove filler cap from master cylinder filler tube and install on master cylinder.
Disconnect electrical connector at brake fluid level sensor located on master cylinder fluid reservoir. Place shop towel under master cylinder to absorb brake fluid.
Disconnect brakelines from master cylinder. Install plugs at brakeline outlets on master cylinder. Clean master cylinder-to-power brake booster area to prevent dirt particles from falling into power brake booster. Remove master cylinder-to-power brake booster nuts and slide master cylinder from power brake booster.
Remove master cylinder-to-power brake booster vacuum seal from groove on mounting flange of master cylinder by pulling vacuum seal from master cylinder. DO NOT pry vacuum seal from master cylinder.
CAUTION: Master cylinder-to-power brake booster vacuum seal MUST always be replaced. DO NOT reuse vacuum seal.
Bench bleed master cylinder before installing.
See BENCH BLEEDING MASTER CYLINDER under BLEEDING BRAKE SYSTEM below.
Ensure NEW master cylinder-to-power brake booster vacuum seal is squarely installed in groove on mounting flange of master cylinder before installing master cylinder.
Ensure push rod in power brake booster aligns with piston in master cylinder. Tighten master cylinder-to-power brake booster nuts and brakeline nuts to specification.
On models without ABS, bleed brake system. On models with ABS it is not necessary to bleed the Hydraulic Control Unit (HCU) on the ABS, but the base brake system must be bled
BENCH BLEEDING MASTER CYLINDER
NOTE: Bleeder tubes must be installed on master cylinder when performing bleeding procedure.
Clamp master cylinder in soft-jawed vise at mounting flange on master cylinder.
Install Bleeder Tube (6920) in each outlet port on master cylinder with ends of bleeder tubes positioned in brake fluid reservoir on master cylinder.
Fill master cylinder with brake fluid.
Ensure ends of bleeder tubes are submerged in the brake fluid in brake fluid reservoir on master cylinder.
Using wooden dowel, slowly depress pistons in master cylinder and then release, allowing pistons to return.
Repeat procedure until no bubbles exit from bleeder tubes.
Remove bleeder tubes and plug master cylinder outlets to keep fluid from draining.