ninaschwarz1
Mercedes R Klasse engine noise issue
Summary of the thread
A 2010 Mercedes R Klasse owner reported concerning engine noise, suspecting a faulty belt tensioner. The issue was linked to the serpentine belt handover not functioning correctly, possibly due to a defective belt bringer/handover. After consulting with a mechanic, it was confirmed that the belt tensioner was the cause, and replacing it, along with the serpentine belt, resolved the noise issue.
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4 comment(s)
ninaschwarz1 (community.author)
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?
martin_lang1
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.
ninaschwarz1 (community.author)
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.
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MERCEDES
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RKLASSE
martin_lang1
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.