Bmw Serpentine Belt And Pulley Replacement, How to

Hi, Otto here for Bavarian Autosport. Today we are going to show you how easy it is replace the accessory drive belts and pulleys on late model BMW's with serpentine belts. We will be working with a 2001 Z3 with the M54 3 liter engine. Other applications will be similar. First, we will remove the air filter box. Loosen the intake bellows hose clamp. Remove the air flow meter harness plug. Depress the steel clip to remove the plug. Loosen the air filter box mounting nut. Note the coolant bleeder hose on this model. Unclip the hose from the air filter box. Separate the air flow meter from the intake bellows, and carefully lift the box from the vehicle. We will now remove the fan and the fan shroud. We will use the fan clutch wrench and the pulley holder tool, in order to remove the fan clutch assembly. Fit the end of the pulley holder tool over one of the water pump pulley bolts and see if the cut out on the side of the tool against the fan clutch nut. Note the fan clutch wrench has a 32mm end a 36mm end. The 36mm end can be used on some applications for the oil filter cap. The 32mm end is used for the fan clutch. Position the wrench on the fan clutch nut forward of the pulley holder tool. Typically the nut will be too tight to loosen by just pressing against the pulley holder and the wrench. Also note, the nut is left hand thread and turns clockwise to loosen. In this case, hold the pulley holder, and tap the wrench with a hammer to shock it loose. Loosen the nut, until you can spin the fan assembly by hand to fully loosen and remove the assembly from the water pump. In most cases you will not be able to remove the fan without also removing the shroud. The fan shroud will be secured via clips, screws or plastic rivets. This model is secured with two plastic push-pin rivets. Use a small screw driver or pry tool to pull out the center pin, than remove the pin and the rivet using needle nose pliers. Pull out the shroud and fan assembly together. Here is the 32mm nut on the back side of the fan clutch. Note how the wrench fits on the nut. For this video, we have removed the radiator, so that we could have a better view with the camera. This is not necessary in replacing the belts and pulleys. Note the air conditioning belt and tensioner pulley must be removed before the main belt and pulley. For this model first remove the upper mounting bolt for the A/C tensioner assembly as it will be inaccessible one the belt is removed and the tensioner is detensioned. We can now detension the tensioner using a ratchet and socket on the hex fitting on the tensioner housing. Rotate the tensioner to release the pulley's tension on the belt and remove the belt. This model uses the mechanical tensioner assemblies, some models use hydraulic tensioners. The removal procedures are slightly different and are addressed in the Bentley Repair Manuals. We can no detension the main belt tensioner pulley and remove main belt. Note the hex fitting that is used for detensioning. Some models require the plastic cover on the pulley to be removed and the center bolt of the pulley is used for the detensioning. Remove the two tensioner assembly mounting bolts. The new tensioner will come with a locking pin installed; this prevents access to the lower mounting bolt. We will install the tensioner with the upper mounting bolt, and then remove the locking pin. Do not tighten the upper mounting bolt yet. Detension the unit slightly, and pull the locking pin out. Install the lower mounting bolt and finish by tightening both mounting bolts. We can now replace the air conditioner belt tensioner in a similar manner. The A/C tensioner pulley was recently replaced on this vehicle so we will not be removing it. Install the new main belt by loosely positioning it around the accessory and crank shaft pulleys. Note the routing of the belt and the loop that will go over the tensioner pulley. Detension the pulley and slip the belt over the pulley. Make sure the belt is fully seated in the groves of all of the pulleys. Install the A/C belt in a similar manner. Be sure the belt is properly seated in all pulleys. Install the fan and shroud. Turn the fan counter clockwise to start the fan clutch nut onto the water pump. If you have trouble starting the fan by hand, try using the wrench. Spin the fan to run the nut fully up on the water pump threads. Once the nut is seated, use the wrench to snug it tight. Don't worry about applying a lot of torque; the clockwise engine rotation will keep the nut tight. Position the fan shroud and install the plastic locking pin rivets. Insert the rivet and then press the center pin fully into the rivet to lock it. Install the air filter box. That's it. You're all done.