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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 509 (Disc Brakes & Drum Brakes) >> Bleeding Brake System >> Hydraulic System Flushing

Hydraulic System Flushing

WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
  1. Inspect the brake fluid for the following conditions, indicating brake fluid contamination:
    1. Fluid separation (indicating 2 types of fluid are present; a substance other than the recommended brake fluid has been introduced into the brake hydraulic system)
      • Swirled appearance - oil-based substance.
      • Layered appearance - silicone-based substance.
    2. Fluid discoloration (indicating the presence of moisture or particles that have been introduced into the brake hydraulic system)
      • Cloudy appearance - moisture.
      • Dark appearance - suspended particles in fluid, dirt, rust, corrosion, brake dust.
  2. Inspect the master cylinder reservoir cap diaphragm and the reservoir-to-master cylinder grommets for swelling, indicating brake fluid contamination.
  3. If the brake fluid was contaminated with an oil-based or a silicone-based substance (indicated by fluid separation and/or a swollen master cylinder reservoir cap diaphragm and/or swollen reservoir-to-master cylinder grommets), perform the following:
    1. Remove ALL of the following components listed from the vehicle. Each component contains internal rubber seals/linings which have been contaminated by the contaminated brake fluid in the brake hydraulic system. Refer to the procedures indicated.
      • See MASTER CYLINDER  under REMOVAL & INSTALLATION.
      • See FRONT BRAKE HOSE  under REMOVAL & INSTALLATION.
      • See REAR DISC BRAKE HOSE  under REMOVAL & INSTALLATION.
      • See REAR DRUM BRAKE HOSE  under REMOVAL & INSTALLATION.
      • See FRONT BRAKE CALIPER  under REMOVAL & INSTALLATION.
      • See REAR BRAKE CALIPER  under REMOVAL & INSTALLATION.
      • See WHEEL CYLINDER  under REMOVAL & INSTALLATION.
      • On vehicles without ABS, replace proportioning valve. See PROPORTIONING VALVE  under REMOVAL & INSTALLATION.
      • On vehicles with ABS, replace Brake Pressure Modulator Valve (BPMV). See appropriate ANTI-LOCK article.
      • On vehicles with manual transmission, replace hydraulic clutch components. See appropriate CLUTCHES article in TRANSMISSIONS.
    2. Clean out all the hydraulic brake pipes using denatured alcohol (or equivalent).
    3. Dry the brake pipes using non-lubricated, filtered air.
    4. Repair or replace ALL of the following components listed. Each component contains internal rubber seals/linings which have been contaminated by the contaminated brake fluid in the brake hydraulic system. Refer to the procedures indicated.
      • Clean the brake master cylinder reservoir using denatured alcohol (or equivalent), then dry the reservoir using non-lubricated, filtered air. Inspect the reservoir for cracks and/or damage and replace if necessary. See MASTER CYLINDER RESERVOIR  under REMOVAL & INSTALLATION. Replace the brake master cylinder reservoir cap diaphragm.
      • See FRONT BRAKE HOSE  under REMOVAL & INSTALLATION.
      • See REAR DISC BRAKE HOSE  under REMOVAL & INSTALLATION.
      • See REAR DRUM BRAKE HOSE  under REMOVAL & INSTALLATION.
      • See FRONT BRAKE CALIPER  under REMOVAL & INSTALLATION.
      • See WHEEL CYLINDER  under REMOVAL & INSTALLATION.
      • On vehicles without ABS, replace proportioning valve. See PROPORTIONING VALVE  under REMOVAL & INSTALLATION.
      • On vehicles with ABS, replace Brake Pressure Modulator Valve (BPMV). See appropriate ANTI-LOCK article.
      • On vehicles with manual transmission, replace hydraulic clutch components. See appropriate CLUTCHES article in TRANSMISSIONS.
  4. If the brake fluid was not contaminated with an oil-based or a silicone-based substance, but was contaminated with water or dirt, rust, corrosion, and/or brake dust, replace the brake master cylinder reservoir cap diaphragm which may have allowed the moisture or particles to enter the hydraulic system.
  5. Fill the brake master cylinder reservoir to the maximum-fill level with Delco Supreme 11(R) (GM P/N 12377967) or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
  6. Manually bleed the hydraulic brake system. See MANUAL BLEEDING  .
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