How to Change Serpentine Belts in a BMW 323IS

1. Open the hood on the BMW 323IS and lock it in place.
2. Locate the serpentine belt routing diagram. The diagram on the BMW 323IS is located either on the top of the fan shroud or on the bottom side of the hood. If you do not see the serpentine belt routing diagram, sketch out the routing direction of the belt around the pulleys on a notepad.
3. Locate the serpentine belt spring-loaded tensioner on the front of the engine. The tensioner on the BMW 323IS is located in the center of the engine. The tensioner has a pulley on one end and a spring-loaded arm on the other. The pulley on the tensioner has a flat plate in the center of the pulley. This flat plate has to be removed to access the 8 mm hex hole.
4. Pry the center plate off of the center of the tensioner pulley with a flat head screwdriver.
5. Insert an 8 mm hex head socket into the hex hole in the center of the belt tensioner. Turn the tensioner clockwise with the 1/2-inch drive ratchet to relieve the tension from the serpentine belt. Slide the belt off of the tensioner pulley manually.
6. Slide the serpentine belt off of the remaining pulleys. Slide the belt from around the fan and remove the belt from the engine compartment.
7. Route the new serpentine belt around the fan and onto the bottom crankshaft pulley first.
8. Route the belt around the remaining pulleys as directed by the serpentine belt diagram. Leave the tensioner pulley for last.
9. Rotate the tensioner pulley clockwise again with the 1/2-inch drive ratchet and the 8 mm hex head socket. Slide the belt onto the tensioner pulley with by hand. Release the tensioner. Make sure that the belt is routed around all of the pulleys.
10. Insert the center plate back onto the center of the tensioner. Use the back of the screwdriver to tap the center plate in place.
11. Crank the BMW 323IS and inspect the serpentine belt to make sure that the belt stays seated inside of all of the pulleys while the engine is running. Turn the engine off.