Brake System Inspection

• 1). Set the vehicle in "Park" and apply the emergency brake. Use a jack to lift the vehicle to a height that allows you to set two jack stands under one axis at a time. Use the tire iron to remove the wheels, then set them aside.
  
  
• 2). Inspect the wheel cylinders for leaks by gently pulling back the rubber boots. In the case of the front disk brakes, inspect the inside of the caliper, near the piston location. Check all the wheels in this manner. Any brake fluid leakage in these areas means that you can rule out failure of the master cylinder for now. If no leakage exists, the problem will point to the master cylinder.
  
  
• 3). Lower the vehicle and remove the stands. Open the hood. Remove the master cylinder reservoir cap and inspect the fluid level in the reservoir. There should be a line denoting the fill limit near the top. If no limit line exists, raise the level with new brake fluid until it reaches approximately 3/8 before the top lip of the reservoir. Good brake fluid quality shows with a clear liquid. If the fluid appears murky, muddy, milky or discolored in any way, it means it has been contaminated. Water condensation will be the most likely source of contamination. Since water has a different boiling point and gets hot at the wheel cylinders, it renders the brake fluid incapable of compressing completely. A full brake bleed remedies this situation.
  
  
• 4). Inspect the rear of the master cylinder, where it bolts to the power booster (the large circular canister on the firewall). Look for any brake fluid leakage that has run down the seam between the joint. Brake fluid contains highly corrosive chemicals and will blister paint, which might show on the surface of the brake booster. Any leakage here indicates the rear master cylinders seals have failed, and the master cylinder needs to be replaced.
  
  Check for leakage where the plastic fluid reservoir sits on top of the master cylinder. Grommets seal the joint at this junction, and sometimes they wear through due to corrosion. Any leakage down either side of the master cylinder body indicates grommet-seal failure. Replace the master cylinder.
  
  
• 5). Sit behind the wheel and start the engine. Without pumping the brake pedal, apply a steady but firm force on the pedal and note its travel. A brake pedal that continues to depress all the way to the floorboard means a leak has allowed the master cylinder to lose full pressure. Sometimes pumping the pedal several times will restore brake height, but it will always depress slowly to the floor. This type of leak can be caused by internal seals that have broken or worn and show no outwards signs of leakage. The most probable cause points to bad seals within the master cylinder, which requires a replacement.
  
  
• 6). Sit behind the wheel. Feel the condition of the brake pedal under your foot when you depress it. If it has a spongy or bouncy feeling, this means that air has somehow entered the brake line system or the master cylinder. There will not be a firm-hard pedal response. A brake bleed will solve a problem like this, provided all other brake components are functioning properly.
  
  
• 7). Check your dashboard for any brake light indicator warning light. If a code appear next to or in place of the brake warning light, look it up in your manual or in a trouble code reference book to identify the problem area.