|Sprinter II 2007-2018 3.0L V6 Diesel
This is the main serpentine belt tensioner. If you have rear A/C, see the secondary tensioner/damper assembly, shown below.
If you have had premature failures of this tensioner , serpentine belt, or any of the other pulleys and items driven by the belt, you most likely have a failed alternator pulley. The alternator pulley is a decoupling/declutching pulley and has a one-way clutching mechanism to minimize belt flutter. Belt flutter places stress on the entire belt drive system and the tensioner acts as a spring-loaded shock absorber. If the declutching pulley has seized, it will greatly shorten the life of the belt tensioner and often causes the pulley to break off or a fracture of the pulley arm. Replace the alternator pulley or the alternator in order to solve this problem.See this video for more info: http://www.gatesprograms.com/adp