Skip to content

DIY: Drive Belt Replacement

The M54 uses a single serpentine belt that drives the alternator, power steering pump, A/C compressor, and water pump.

  • Serpentine belt: 6PK1538 (11 28 7 838 200)
  • Optional: Belt tensioner and idler pulley
  1. Note belt routing (diagram on fan shroud or take photo)
  2. Place 17mm wrench on belt tensioner bolt
  3. Rotate tensioner clockwise to release tension
  4. Slip belt off one pulley
  5. Slowly release tensioner
  6. Remove old belt completely
  7. Route new belt according to diagram
  8. Rotate tensioner again to slip belt over last pulley
  9. Verify belt is properly seated in all pulleys
  10. Start engine and verify belt tracks correctly

Replace the tensioner and idler pulleys if:

  • Belt squeals or chirps
  • Tensioner arm wobbles or doesn’t spring back
  • Idler pulley has play or roughness when spun
  • Over 80,000 miles as preventive maintenance