Mercedes-Benz C 350
Four-valve V6 with variable valve timing. Smooth and powerful. Known for balance shaft wear (revision sprocket) on early build years. Balance shaft gear problem addressed by Mercedes with a recall.
C 350 — Solid Performance
200 kW V6 in the W204 turns the C-Class into a genuine everyday sports car. Rich, refined, with reserves. Worth it.
Engine Weaknesses 6
The plastic balance shaft sprocket on the M272 wears prematurely from the timing chain. The right cylinder bank goes out of timing. Affected up to end of October 2006.
Symptoms: Fault codes P0016/P0017 (camshaft right bank), chain rattling, rough running at idle, in extreme cases engine damage
Alongside the balance shaft issue the M272 shows premature timing chain stretch. Chain wear on softer sprockets leads to timing deviations.
Symptoms: Chain noise especially on cold start, camshaft fault codes, rough running, engine irregularities
Four camshaft adjuster solenoids (two per cylinder bank) develop leaks; oil creeps into the wiring harness as far as the ECU. Repair costs up to €1,700 documented.
Symptoms: CEL, oil traces at camshaft connectors, lambda sensor failure due to oil contamination, non-specific faults that recur
Plastic components of the M272 variable intake system become brittle and break. The intake flap linkage snaps and sets fault code P2006.
Symptoms: Fault codes P2004/P2005/P2006 (intake flap), slight power loss, check engine light
The thermostat on the M272 preferentially fails in the open position. Operating temperature is not reached; especially on motorway runs temperature drops to 75–80°C.
Symptoms: Engine doesn't reach 90°C after 10–20 km, coolant temperature fluctuates heavily, reduced heater output, fault code P0128
The hydraulic engine mounts on the M272 lose their damping effect with age. Jerky movements are especially apparent when lifting off the throttle and during gear changes.
Symptoms: Vibrations in steering wheel and gear lever during load changes, judder on gear changes, droning at low revs
Vehicle Weaknesses 7
Rear subframe rusts from the inside out. Problem not immediately visible externally. In severe cases the rear differential can shift.
Brake lines corrode relatively quickly and are flagged at MOT. Affected two to several times more frequently than the vehicle average.
W204 rear subframes systematically rust through from the inside. Powder coat cracks and moisture penetrates. Mercedes replaces under goodwill (15 years from first registration). In extreme cases the axle breaks.
Brake lines above the rear axle rust through after approximately 8–10 years. Brake fluid loss and brake failure possible. Mercedes goodwill arrangement known up to 8 years.
Pre-facelift models (up to 2011) show clunking front axles from defective shock absorbers, strut top mounts and wishbones. Improved after facelift.
Xenon headlight levelling actuators fail frequently. Error message and dazzling of oncoming traffic.
Shock absorbers and strut mounts of the front axle wear prematurely on the W204. Rumbling and wallowing typical from 100,000 km.