GM Service Manual Online
For 1990-2009 cars only

Flushing Brake Hydraulic System

Important: 

   • If evidence of contamination is present in the vehicle's brake fluid, flush the entire brake system following one of the following procedures.
   • Flush the system under the following conditions:
   • If there is any doubt about the condition of the fluid in the system
   • If the fluid that is used contains the slightest trace of mineral oil (from such things as engine oil, transmission fluid, etc.)
   • After flushing the entire brake system, replace all rubber components.
   • Replace the following components:
   • The brake hose assemblies
   • The master cylinder rubber parts
   • The brake caliper seals
   • The brake modulator
   • The brake solenoid valves
   • Refer to the appropriate replacement procedures.
   • After replacing all rubber components, re-flush the entire brake system by performing one of the following procedures.
   • After performing the second flushing procedure, perform a complete system bleed. Refer to Hydraulic Brake System Bleeding .

Caution: Use only Delco Supreme 11, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT 3 brake fluid from a clean, sealed container. Do not use fluid from an open container that may be contaminated with water. Improper or contaminated fluid could result in damage to components, or loss of braking, with possible injury.

Caution: Do not overfill the brake fluid reservoir. Overfilling the brake fluid reservoir may cause the brake fluid to overflow onto the engine exhaust components during brake system service. The brake fluid is flammable and may cause a fire and personal injury if the brake fluid contacts the engine exhaust system components.

Pressure Flushing

Tools Required

    • J 29532 Diaphragm Type Brake Bleeder
    • J 35589 Compact Brake Bleeder Adapter

    Object Number: 241624  Size: SH

    Notice: Pressure Bleeding equipment can be used to perform the flush procedure. The pressure bleeding equipment used for flushing must be of the diaphragm type. It must a have a rubber diaphragm between the air supply and the brake fluid to prevent air, moisture, and other contaminants from entering the hydraulic system.

  1. Clean the brake fluid reservoir cover and the surrounding area.
  2. Remove the brake fluid reservoir cover.
  3. Remove any remaining brake fluid in the reservoir.
  4. Refill the brake fluid reservoir with clean DOT 3 brake fluid to the proper level.
  5. Install the J 35589 to the brake fluid reservoir.
  6. Install the J 35589 to the pressure bleeding equipment.
  7. Adjust the pressure bleeding equipment to 35-70 kPa (5-10 psi) and wait for approximately 30 seconds in order to ensure there is no leakage.
  8. Adjust the pressure bleeding equipment to 205-240 kPa (30-35 psi).
  9. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  10. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


    Object Number: 179295  Size: SH

    Important: The following list indicates the wheel position flush sequence:

    1. Right rear
    2. Left front
    3. Left rear
    4. Right front

    Important: Ensure that the bleeder valves do not leak.

  11. Use the following procedure in order to flush the brakes:
  12. 10.1. Attach the bleeder hose to the bleeder valve at each wheel.
    10.2. Place the other end of the bleeder hose into a container in order to collect the draining brake fluid. Do not submerge the hose end in fluid.
    10.3. Slowly open the bleeder valve and allow the fluid to flow.
    10.4. Close the valve when clean brake fluid begins to flow or at least 235 ml (8 oz) of fluid accumulates.

    Tighten

    1. Tighten the front caliper bleeder valves to 13 N·m (115 lb in).
    2. Tighten the rear caliper bleeder valves to 7 N·m (62 lb in).
  13. Lower the vehicle.
  14. Remove the bleeder adapter.
  15. Replace any rubber components damaged, cracked, or worn under Flushing Procedure. Refer to the appropriate On-Vehicle Service section.
  16. Repeat the flushing procedure one more time.
  17. Inspect the brake fluid level in the reservoir. Fill the reservoir to the correct level if necessary.
  18. Install the brake fluid reservoir cap.
  19. Bleed the entire brake hydraulic system. Refer to Hydraulic Brake System Bleeding .

Manual Flushing

    Important: Use a suitable container and/or shop rags in order to catch fluid and prevent the fluid from contacting any painted surfaces.

  1. Clean the brake fluid reservoir cover and the surrounding area.
  2. Remove the brake fluid reservoir cover.
  3. Remove any remaining brake fluid in the brake fluid reservoir.
  4. Refill the brake fluid reservoir with clean DOT 3 brake fluid to the proper level.
  5. Install the brake fluid reservoir cover.
  6. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

  7. Object Number: 179295  Size: SH

    Important: The following list indicates the wheel position flush sequence:

    1. Right rear
    2. Left front
    3. Left rear
    4. Right front

    Important: Ensure that the bleeder valves do not leak.

  8. Use the following procedure in order to flush the wheel brakes:
  9. 7.1. Attach the bleeder hose to the bleeder valve at each wheel.
    7.2. Place the other end of the bleeder hose into a container in order to collect the draining brake fluid. Do not submerge the hose end in fluid.
    7.3. Slowly open the bleeder valve and allow the fluid to flow.
    7.4. Close the valve when clean brake fluid begins to flow or at least 235 ml (8 oz) of fluid accumulates.

    Tighten

        • Tighten the front caliper bleeder valves to 13 N·m (115 lb in).
        • Tighten the rear caliper bleeder valves to 7 N·m (62 lb in).
  10. Lower the vehicle.
  11. Replace all of the following rubber components:
  12. • The brake hose assemblies
    • The master cylinder rubber parts
    • The brake caliper seals
    • The brake modulator
    • The brake solenoid valves
  13. Repeat this manual flushing procedure one more time.
  14. Inspect the brake fluid level in the reservoir. Fill the reservoir to the correct level if necessary.
  15. Replace the brake fluid reservoir cap.
  16. Bleed the entire brake hydraulic system. Refer to Hydraulic Brake System Bleeding .