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

Solution

1. Preparation

• Tools Required: Socket set, screwdrivers, fluid catch pan, safety gloves.
• Ensure the vehicle is parked on a level surface and engage the parking brake.

2. Inspect and Replace Serpentine Belt

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Loosen the tensioner pulley using a wrench to relieve tension on the serpentine belt.
  3. Carefully remove the serpentine belt from the pulleys.
  4. Inspect the belt for cracks, fraying, or glazing.
  5. If damaged, replace with a new belt (OEM recommended).
• Safety Warning: Ensure the engine is off and cool before starting.

3. Check Power Steering System

• Sub-steps:
  1. Locate the power steering reservoir and check the fluid level.
  2. If low, add the recommended power steering fluid.
  3. Inspect hoses and connections for leaks or damage.
  4. If noise persists, consider replacing the power steering pump.
• Tools Required: Fluid catch pan, funnel.

4. Transmission Fluid Inspection

• Sub-steps:
  1. Check the transmission fluid level with the dipstick (if applicable).
  2. Inspect the fluid for discoloration or burnt smell.
  3. If the fluid is low or dirty, perform a transmission fluid change.
• Tools Required: Transmission fluid, funnel.

5. Examine Wheel Bearings

• Sub-steps:
  1. Lift the vehicle securely with jack stands.
  2. Spin each wheel by hand to listen for noise or roughness.
  3. If play is detected, replace the affected wheel bearing.
• Tools Required: Jack stands, socket set.