One of the most common issues with M5X and S5X series engines is the Vanos system. Common symptons of a failing vanos system is a sound similar to marbles rattling around which can be noiced at engine idle. 
 
TCE's Single Vanos rebuild kits are produced with factory improved Beisan Systems components. With tighter manufacturing tolerances on the roller bearing locating ring, and seals made from high temperature Teflon and Viton, these components are top notch and an great improvement over the factory delivered Vanos units. 
 
There is also an option to include a modified socket tool to make sure your DIY goes smoothly! It is 18mm which will fit all Vanos units with exception to those produced in 1993.