How to Replace Serpentine Belt Tensioner 01-05 BMW 325Xi

Difficulty: Intermediate · About 80 min · Bmw 325xi

Replace the serpentine belt tensioner on a 2001–2005 BMW 325xi and route both accessory belts according to the underhood diagram.

Steps

1. Disconnect power and remove the fan shroud

   Disconnect the negative battery cable and remove the air collector retainers. Unplug the fan wiring, release the shroud fasteners, then use the correct reverse-thread fan clutch tool to remove the fan and shroud together.

2. Remove the accessory belts

   Relieve the air conditioning belt tension and remove that belt. Release the main belt tensioner, secure it with its service pin, then remove the main belt and idler as needed for access.

3. Replace the tensioner

   Release the tensioner carefully and remove its mounting bolts. Position the replacement tensioner in the same orientation, start its bolts by hand, and tighten them to the vehicle specification; reinstall the idler and verify its alignment.

4. Route both belts

   Route the main belt according to the vehicle diagram, relieve the tensioner, and remove its service pin gradually. Install the air conditioning belt on its pulleys, release its tensioner, and check that each belt is centered in every groove.

5. Reinstall the fan and verify

   Lower the fan and shroud into place, secure their fasteners, reconnect the electrical plugs, and reinstall the air collector. Reconnect the battery and briefly run the engine while checking for belt tracking and abnormal noise.

Check your vehicle’s repair manual for exact specifications and fit.