my Tesla Model 3 has a leaking brake master cylinder, how to fix it?

Solution

1. Preparation

• Gather necessary tools and parts. Ensure the vehicle is parked on a level surface and turn off the ignition.
• Tools Required: Socket set, brake fluid catch pan, wrench set, brake line wrench, torque wrench, and safety glasses.

2. Remove the Old Brake Master Cylinder

• Step 1: Disconnect the negative battery terminal to prevent electrical shorts.
• Step 2: Remove the brake fluid reservoir cap and siphon out any remaining brake fluid into a catch pan.
• Step 3: Disconnect the brake lines from the master cylinder using a brake line wrench to prevent stripping the fittings. Use a catch pan to collect any leaking fluid.
• Step 4: Remove the mounting bolts securing the master cylinder to the brake booster using a socket set.
• Step 5: Carefully pull the master cylinder off the brake booster and inspect the mounting surface for debris.

3. Install the New Brake Master Cylinder

• Step 1: Position the new brake master cylinder onto the brake booster and ensure it seats properly.
• Step 2: Install the mounting bolts and tighten them to the manufacturer’s specified torque values (generally around 15-20 ft-lbs; confirm with service manual).
• Step 3: Reconnect the brake lines to the master cylinder, ensuring they are tightened securely without over-torquing.
• Step 4: Refill the brake fluid reservoir with the recommended brake fluid type (typically DOT 3 or DOT 4; confirm with service manual).

4. Bleed the Brake System

• Step 1: Start by having an assistant pump the brake pedal a few times to build pressure.
• Step 2: Open the bleeder valve on the furthest brake caliper from the master cylinder (usually the rear passenger side) and let air and fluid escape until it runs clear. Close the valve and repeat this step for each wheel in order: rear passenger, rear driver, front passenger, front driver.
• Step 3: Monitor the brake fluid level during this process and refill as necessary to prevent air from entering the system.