why is my BMW 3 Series E90/E91 (2005-2012) making a whining noise while driving

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is off.
• Tools Required: Jack and jack stands, socket set, torque wrench, stethoscope (or long screwdriver), fluid catch pan.

2. Inspect and Replace Serpentine Belt

• Sub-steps:
  1. Remove the engine cover (if applicable) using a socket set.
  2. Release tension on the serpentine belt using a wrench on the tensioner.
  3. Remove the old belt and inspect pulleys for wear or damage.
  4. Install a new serpentine belt, ensuring it is routed correctly around all pulleys.
  5. Reapply tension on the tensioner and double-check belt alignment.

3. Check and Top Off Fluids

• Sub-steps:
  1. Check transmission fluid level via dipstick (ensure the vehicle is at operating temperature).
  2. Add the correct type of fluid if levels are low (consult owner’s manual for specifications).
  3. Inspect power steering fluid level and top off as needed.
  4. Check differential fluid level, and add if necessary.

4. Inspect and Replace Wheel Bearings (if needed)

• Sub-steps:
  1. Lift the vehicle and remove the wheels using a socket set.
  2. Inspect wheel bearings for play or roughness.
  3. If bearings are damaged, remove the hub assembly and replace the bearings.
  4. Reassemble wheel and torque lug nuts to manufacturer specifications.

5. Inspect and Replace Alternator (if needed)

• Sub-steps:
  1. Disconnect the battery to prevent electrical shock.
  2. Remove the serpentine belt again to access the alternator.
  3. Unplug the electrical connector and remove mounting bolts.
  4. Install the new alternator and reconnect the electrical connections.
  5. Reinstall the serpentine belt and reconnect the battery.