Model: 2013-’14 S-Class (W222)
Complaint: Possible howling noise in the drivetrain in the area of the rear axle between 80 km/h and 110 km/h (50 mph to 70 mph).
Cause: Resonance in the drivetrain stimulated by the meshing of the gear set in the rear axle differential (drive pinion/ring gear).
Remedy: The replacement of any other components is not effective. A test drive must be performed. For an accurate analysis and localization of the noise, use the “Chassis Ear” noise diagnosis kit (SI 58.40-P-0036A). If the rear axle differential can be clearly identified as the reason for the fault, then check at the left side shaft, whether a rotary mass damper (see Fig. 1) has been installed on the left inner joint. If a side shaft without rotary mass is installed, order a side shaft according to parts list (see Fig. 2).
Courtesy of ALLDATA.