my Volvo XC90 brakes feel spongy, what can be causing this?

Solution

1. Preparation

• Gather tools and parts.
• Wear safety gloves and goggles.
• Ensure the vehicle is on a flat surface and securely lifted with jack stands.

2. Inspect and Replace Brake Fluid

• Sub-steps:
  1. Remove the cap from the brake fluid reservoir.
  2. Check fluid condition; replace if contaminated or low.
  3. Use DOT 4 brake fluid; fill to the recommended level.

3. Check and Repair Brake Lines

• Sub-steps:
  1. Visually inspect all brake lines for signs of wear, corrosion, or leaks.
  2. If leaks are found, replace the affected brake line section using a flare wrench.
  3. Bleed the brake lines to remove air after replacing any lines.

4. Inspect and Replace Brake Components

• Sub-steps:
  1. Remove the wheel to access brake components.
  2. Check brake pads and rotors for wear; replace if thickness is below specifications.
  3. Reassemble wheels and torque to manufacturer's specifications.

5. Bleed the Brake System

• Sub-steps:
  1. Start at the furthest wheel from the master cylinder (usually the rear passenger side).
  2. Attach a clear hose to the bleeder valve and place the other end in a container.
  3. Have an assistant press the brake pedal while you open the bleeder valve; close it once fluid flows out.
  4. Repeat until no air bubbles are visible in the fluid.
  5. Move to the next wheel and repeat the process until all wheels are bled.