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Stan
Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
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2009 S class 320 has developed a high pitch whining noise at

Customer Question

2009 S class 320 has developed a high pitch whining noise at low revs
Submitted: 1 year ago.
Category: Mercedes
Expert:  Stan replied 1 year ago.
Hello,
Such symptom is caused by v-belt issues- worn v-belt, belt tensioner failure, alternator clutch failure. So all of the pulleys and units in the belt line should be checked.
Best Regards,
Stan