The serpentine belt on the BMW 316I has a tensioning device that holds the serpentine belt onto the engine accessory pulleys. The serpentine belt makes it possible to control all of these engine accessories with one belt instead of two different belts. When the motor is cranked and running, the crankshaft pulley drives the serpentine belt around the other pulleys. This enables each engine accessory to function. If the serpentine belt becomes damaged, such as cut or torn, it will have to be replaced before it completely breaks.
Park the BMW 316I in a safe and level work area. Pull the hood latch and open the bonnet.
Inspect the top of the radiator for the serpentine belt routing diagram. This diagram on the BMW 316I model cars can be found on the plastic cover that is on top of the radiator or on the underside of the hood near the front.
Inspect the front of the engine for the serpentine belt tensioning device. This device will have a pulley on one end and a round shaped spring loaded tensioner on the other end. Use the 3/8 inch square hole on the spring loaded arm to turn the whole tensioning device.
Insert the square end of the 3/8-inch serpentine belt removal tool in to the 3/8 inch square hole on the tensioning device. Turn the tensioning device counter clockwise to loosen the belt. Then remove the belt from one of the top accessory pulleys with your other hand.
Pull the serpentine belt off of the other accessory pulleys. Then route the serpentine belt around the fan blades and out of the engine area.
Route the new serpentine belt around the fan blades and onto the crankshaft pulley. Then follow the directions on the serpentine belt routing diagram for routing the new belt around the remaining pulleys. Leave one of the top accessory pulleys for last.
Turn the tensioning device counter clockwise again with the belt removal tool. Then, slide the new belt onto the top pulley with your other hand. Release the tensioning device and pull the tool out of the square hole.
Inspect the new serpentine belt to ensure that it has been routed around the pulleys correctly. Also inspect the belt to ensure that it is completely inside of the pulleys.
Crank the BMW 316I up and let it run for about one minute to completely seat the new belt inside of the grooves on all of the accessory pulleys. Then, turn the engine off.
You can also write down your own serpentine belt routing diagram if you cant locate the routing diagram on the vehicle. Take a pen and paper and draw out the exact routing method of the old belt as it is routed around the pulleys. Then use the diagram when routing the new belt.
Take the keys out of the ignition before beginning any work in the engine compartment. This will prevent accidental cranking of the engine.