Front thrust arm and control arm bushings can crack and sometimes tear completely. If this is not repaired quickly, damage to the front subframe unit will occur, which is very expensive to repair. Updated control arms (that prevent damage to the subframe when the bushings wear out) are available.Google+
Car Problem Reports
Mercedes-Benz S430 4MATIC Front Thrust Arm and Control Arm Bushing Can Crack or Tear
Mercedes-Benz S430 4MATIC Problem
Visitor, 2004 Mercedes-Benz S430 4MATIC, 120,000 mi
Brought car in for service at MB dealership and was told needed to replace control arms bushings. Expensive repair.