why does my BMW 3 Series F30/F31 (2012-2019) make a whirring noise when starting

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Battery Inspection

• Sub-steps:
  • Remove the battery cover (if applicable).
  • Clean battery terminals using a wire brush.
  • Tighten connections to ensure a solid connection.
• Tools Required: Wire brush, socket set.
• Safety Warnings: Ensure all electrical systems are powered down.

3. Starter Motor Replacement

• Sub-steps:
  • Remove the engine cover if necessary for access.
  • Disconnect the wiring harness from the starter motor.
  • Unbolt the starter motor from its mount (usually requires a socket wrench).
  • Remove the starter motor from the vehicle.
  • Install the new starter motor by reversing the removal steps.
• Tools Required: Socket set, torque wrench.
• Safety Warnings: Be cautious of sharp edges and moving parts.

4. Testing the New Starter

• Sub-steps:
  • Reconnect the negative battery terminal.
  • Start the vehicle to test the new starter.
  • Listen for any abnormal sounds during the starting process.
• Tools Required: None.
• Safety Warnings: Ensure the vehicle is in neutral or park before starting.