Mercedes R Klasse engine noise issue

I have a similar Mercedes R Klasse, though I'm uncertain about the build year. I had a comparable issue. Did you notice any unusual wear on the serpentine belt itself, or specifically where it interacts with the tensioner pulley? I am thinking it might be the same.

Thanks for the reply. I inspected the serpentine belt and noticed some minor fraying, but nothing extreme. The tensioner pulley, however, appears to have excessive play. Was your issue also intermittent, or was the engine noise constant?

Mine was constant once it started. Given the play you're seeing, it definitely points to the tensioner. Honestly, I'd recommend getting it checked at a workshop to be certain. Better safe than sorry with engine components.

Thanks for confirming. I took your advice and brought it to a trusted mechanic. They confirmed it was indeed the belt tensioner, and the replacement resolved the engine noise. The serpentine belt was also replaced as a precaution. The automobile maintenance cost was as predicted. Appreciate the help.