my Volvo XC90 brake pedal goes to the floor what's causing this

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Wear safety glasses and gloves for protection.

2. Check and Refill Brake Fluid

• If the fluid level is low, top it up with the manufacturer-recommended brake fluid (DOT 4 or as specified).
• Inspect the brake lines for any visible cracks or damage.

3. Inspect and Repair Leaks

• Identify the source of any leaks:
  • If the master cylinder is leaking, remove it by unscrewing the bolts and disconnecting the brake lines.
  • Replace with a new master cylinder if necessary.
• If the brake lines are damaged, replace the affected sections:
  • Cut the damaged line and replace it with a new brake line of the same diameter.
  • Ensure all connections are tight and apply brake line sealant if required.

4. Bleed the Brake System

• Use a brake bleeder kit or have an assistant pump the brake pedal while you open the bleeder valves on each brake caliper, starting from the furthest wheel from the master cylinder.
• Close the bleeder valve after fluid starts flowing without air bubbles, then repeat for each wheel until the system is free from air.

5. Reassemble and Test

• Reinstall any removed components, ensuring all bolts are torqued to manufacturer specifications.
• Test the brake pedal for firmness before road testing the vehicle.