One problem related to engine rattling and whining sounds has been reported for the 2009 Mercedes Benz R350. The most recently reported issues are listed below.
Wife is disabled with a back injury lumbar support has failed 4 times in 7 months part was finally ordered from germany and the item seems fixed whining noise comes from under the hood. Mercedes engineer says it is a ac pressure release valve. . . And refuses to fix it again. . . . . Car was in the dealership 4 times for this.