Mercedes-Benz W212 front end rattle and its causes
The W212 front end rattles over bumps, what can cause it?
Common causes are the anti-roll bar links (drop links) and body bushings, and worn front control arms. The cause varies from car to car, so a single part replacement does not fix the fault in every car.
How do the anti-roll bar parts cause rattling?
The bar link can wear or the body bushing can loosen, causing a metallic knocking as the front axle moves up and down. Tightening the mounting nuts alone is not enough as a repair, but they are worth checking. The bushing is not available separately, so the sway bar is replaced complete with bushings.
Can a clunk when the steering wheel returns be caused by a control arm?
Yes. A loose front control arm can clunk when the steering wheel is returned to straight after a sharp turn. Replacing the upper control arms has stopped the rattle in some cars. Front suspension and steering are safety-critical, so have a workshop inspect and do the replacement.