Mercedes-Benz Tech Tip: Howling Noise From Rear At 50-70 MPH

Mercedes-Benz Tech Tip: Howling Noise From Rear At 50-70 MPH

Vehicle owners may complain of a 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). The cause could be resonance in the drivetrain stimulated by the meshing of the gear set in the rear axle differential (drive pinion/ring gear).

Figure 1

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).

Figure 2

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.

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