This part is listed by BMW as BMW part number 11287799859 (11 28 7 799 859) and is described as the deflection/idler pulley on the main drive belt of M57 Diesel engine used on E70 X5 35d.
Note: there appears to be two different styles of deflection pulley on the M57. This version uses a short 35mm mounting bolt with an Allen head. The other uses a very long 170mm mounting bolt and has a external Torx head. The belt and tensioner are the same.
The deflection, or idler, pulley is located separate from the tensioner pulley and guides the belt around other accessories. The pulley contains a set of bearings, that when worn, will produce a screeching or rumbling sound. It's important to inspect and replace the pulley regularly. Spin the pulley by hand and listen for grinding or rumbling sounds and if there is resistance. All of these are signs of bad bearings. The pulley wheel is made of plastic and they are known to crack and snap and get flung around the engine compartment. They can damage your radiator, hoses, fan, and other critical items that will lead to a more expansive/expensive repair. Since the deflection pulley is bolted in place, not pressed on, it is easily replaced during a routine belt change.
This is an OEM deflection pulley manufactured by INA - the original supplier to BMW for this part, as well as many other bearings and pulleys. As the OEM it meets all of BMW's original design, fitment, and performance requirements and is TUV approved. OEM parts are the best alternative to more expensive Original BMW parts because they are virtually identical without the inflated price tag. This part has a two year warranty.
For full BMW fitment information or for assistance from one of our BMW experts, we recommend calling us at 877-639-9648.
BMW Fitments:
X5 Series
E70 X5 (07-13) > X5 xDrive35d
