Mercedes May Have Cracks in Microweld

June 22, 2020

This bulletin applies to 2018 Mercedes-Benz CLS550 vehicles. A complaint may involve a single throttle lift-off clunking noise from the side shaft when moving off (audible at the outboard end).

The noise is heard once in each instance when changing direction of travel. If the complaint is eliminated by experimentally loosening the outboard collar nut by one turn, the concern may be due to cracking of the microweld between the wheel bearing inner race and the joint housing of the side shaft. Note that the collar nut must always be replaced after being loosened.

Coat the contact surface of the side shaft with wheel bearing using Molykote paint. Remove the side shafts. Clean the contact surfaces, removing any dust, grease, etc. Before using the low friction Molykote paint, be sure to stir or shake thoroughly before applying. Coat the contact surface with Molykote and leave to dry for one hour in its removed condition. Reinstall the side shafts.

Molykote low friction paint is available as P/N A 000 989 01 52.