Mechanical Belt Tensioner - F10 528i, F25 X3 28iX (N52)

This is the mechanical belt tensioner used on the 6-cylinder 2011 F10 528i N52 and the 2011 F25 X3 xDrive 28i N52 (not for RWD sDrive 28i). The tensioner keeps the main accessory belt at the proper tension for driving the accessories - alternator, power steering pump, and A/C compressor. A failing tensioner will allow the belt to loosen or slip resulting in diminished performance, especially from the alternator. In extreme cases the belt can slip off the pulleys and potentially lead to a catastrophic engine failure (rare but documented). As a preventative maintenance plan, we recommend replacing the tensioner at every belt change, or 40-60,000 miles. The extent of damage from a failed belt is worth the extra cost every few years.

This tensioner includes the pulley and Torx mounting bolt (1128530315).

This tensioner is manufactured by INA, the original supplier to BMW for this part and other engine components. Since it is an OEM part, it conforms to the original design that BMW specified for the N52 engine. It comes with a two year warranty.

This part is for the 6-cylinder N52 models only - not for the 4-cylinder turbo N20 models.