The sway bar end link joints may wear and cause a knocking noise over bumps. Loose or warn links should be replaced to correct this type of noise.
Car Problem Reports
Mercedes-Benz C240 4MATIC Worn Sway Bar Link Joints Causing Knocking Over Bumps
Mercedes-Benz C240 4MATIC Problem
Average Mileage: 107,333 mi (68,000 mi - 168,000 mi)
Visitor, 2004 Mercedes-Benz C240 4MATIC, 168,000 mi
Misdiagnosed. Had to change control arm before it was properly diagnosed