Diagnostic: Knocking noise on Mercedes-Benz - Causes and Prices

A knocking noise on a Mercedes-Benz (A, C, E Class, GLC) is a common symptom reported by owners, especially on higher-mileage cars. The noise may occur at low speed (over speed bumps, when manoeuvring) or when turning, and it is important to identify it correctly to avoid unnecessary repairs.

Most common causes on Mercedes

On recent Mercedes models (A-Class W177, C-Class, E-Class, GLC, etc.), the most frequent sources of a front-end knock are wishbone bushes and steering ball joints. The suspension arms are subject to shocks and wear and degrade over time; play develops and causes a sharp knock under acceleration or braking. Steering ball joints can knock when turning the wheel at a standstill or at low speed.

Other possible causes include brake discs (pads moving in the caliper), dampers or auxiliary belts. On M264, M260 and OM654 engines, a rhythmic knock at idle can also come from the dual-mass flywheel or clutch, especially after 100,000 km.

Indicative costs (parts and labour)

For Mercedes vehicles, the following ballpark figures can help you budget:

• Wishbone bushes (front): around €220 to €450 parts and labour (depending on garage).
• Steering ball joints: around €130 to €280 per side parts and labour.
• Dual-mass flywheel: €1,100 to €2,200 and more depending on engine and garage.

These amounts are indicative; a quote from a professional is essential.

What to do in practice

It is advisable to have the suspension and steering components checked by a garage. In the meantime, avoid sporty driving and impacts (kerbs, potholes) to prevent further wear. If the noise only appears under braking, have the discs and pads checked.

A precise diagnosis (description of the noise, when it appears, mileage) helps narrow down the most likely cause. My Auto Check-up helps you structure this information and get a cost estimate before your garage visit.