2001 Chevrolet Express 2500 Brake Service (ONLINE REPAIR MANUALS)

General System

• Inspect components for damage or unusual wear. Replace as required.
• Inspect backing plate mounting bolts and ensure they are tight.
• Inspect wheel cylinders. Excessive fluid indicates cup leakage and need for wheel cylinder replacement. Slight amount of fluid is always present and is considered normal, acting as lubricant for cylinder pistons.
• Check adjuster screw operation. If satisfactory, lightly lubricate adjusting screw and washer with suitable brake lube. If operation is unsatisfactory, replace.
• C clean rust and dirt from shoe contact surfaces on backing plate using fi...

Brake System Bleed

Gravity and vacuum bleeding procedures are not recommended for use with the anti-lock brake system. The manual bleed procedure is the preferred method, although pressure bleeding is also possible. Do not pump the brake pedal during the bleeding process, as fluid aeration may occur.

Manual Bleed

• Raise and support vehicle, then connect a clear plastic tube to brake bleed screw at righthand rear wheel.
• Place free end of tube in a glass jar partially filled with clean brake fluid. Ensure end of tube remains submerged in fluid and master cylinder reservoir is kept full.
• ...

In order to properly service power brake systems, a thorough understanding of the power assist system is necessary. These systems provide a mechanical assist, acting to increase the force applied to the master cylinder piston by the driver while decreasing the effort necessary to obtain acceptable stopping performance.

Hydraulic assist units incorporate a basic open center spool valve, hydraulic cylinder and an accumulator assembly in a common housing. When the brake pedal is depressed, the hydraulic piston moves forward closing off fluid relief passages, the spool valve applies flui...

Astro & Safari

• Apply parking brake.
• Disconnect reservoir and power steering hoses from booster.
• Remove master cylinder to brake booster retaining nuts.
• Position and support master cylinder away from booster. Do not remove hydraulic lines from master cylinder.
• Remove booster rod from top of brake pedal.
• Remove booster mounting nuts from inside of vehicle.
• Remove booster assembly and gasket.
• Reverse procedure to install, noting the following:
• Torque booster mounting nuts to 27 ft. lbs.
• Torque master cylinder retaining nuts to 27 ft. lbs.
• Torque power steering hoses to booster n...

Slow Brake Pedal Return

• Excessive seal friction in booster.
• Faulty spool action.
• Restriction in return line from booster to pump reservoir.
• Damaged input rod end.

Grabby Brakes Or Booster Chatters/Pedal Vibrates

• Faulty spool action caused by contamination in sys...

Disassemble

• Place accumulator compressor tool No. J-26889, or equivalent, around end of accumulator.
• Install nut onto stud as shown in Fig. , then depress the accumulator with a C-clamp.
• Remove retainer by using a punch.
• Release C-clamp and remove accumulator compressor tool.
• Remove accumulator, O-ring, retainer, plug and spring, Fig. .
• Remove retainer, output pushrod, baffle, piston return spring and retainer.
• Using a suitable saw, cut off eyelet of pedal rod, then remove the boot.
• Remove nut, bracket and bolts, then separate cover from housing.
• Remove piston assembly and seal...