Belt Tensioner Assembly, INA - E36, E46, E39, Z3, Z4, Z4M, M50, M54, S52, S54

This is the replacement hydraulic tensioner assembly for the main drive belt on M50, M52, M52TU, M54, and S54 engines. The tensioner is available separately but is also available as a complete assembly with the pulley (see Related Items below). The tensioner is like a small shock absorber that maintains pressure on the belt. A loose belt will cause insufficient charging from the alternator, poor cooling performance from the water pump, and stiffer steering from lower power steering pump output. It might also lead to the belt slipping from the pulleys or premature belt wear.

This tensioner is manufactured by either INA or LUK, both original suppliers 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 engines listed above. This part comes with a two year warranty.