Mercedes-Benz C 200 CDI
Mercedes' first common rail diesel. Economical and torquey, but prone to injector problems and torque limiter failures.
Pure Everyday Diesel
The OM611 with 75 kW in the W202 — solid technology, but not a single spark of driving pleasure. Sensible yes, exciting no.
Engine Weaknesses 6
The dual-mass flywheel on the OM611 wears particularly quickly with a manual gearbox due to the high torque at low revs. LUK recommends preventive replacement from 150,000 km during clutch work.
Symptoms: Rattling and chattering at warm idle, vibrations when pulling away and changing gear, judder at low revs, noise disappears when pressing the clutch
Injector sealing rings wear and allow combustion gases to escape into the injector bore. Deposits on the seating face make disassembly considerably harder.
Symptoms: Poor cold starting, rough idle, faint hissing with engine running, increased fuel consumption
Plastic inlet channel shut-off flaps become brittle through EGR soot deposits and break. Fragments can enter the engine.
Symptoms: Hissing on acceleration, reduced engine braking, engine warning light, power drop
The vacuum actuator for boost pressure control fails; the turbocharger has no more boost pressure regulation. Often only the actuator is defective, but the turbo unit must be replaced.
Symptoms: Severely reduced acceleration, black smoke under load, limp mode, boost pressure fault message
The EGR valve on the OM611 becomes contaminated with soot and carbonised oil and can no longer close fully. Typical problem with short-trip and taxi use.
Symptoms: Power loss, limp mode, engine won't rev past 3,000 rpm, smoke on acceleration, rpm fluctuations at idle
On the OM611, the O-rings on the fuel filter housing harden and allow air into the fuel system. Engine stumbles or barely starts after extended standing.
Symptoms: Starting difficulties after standing, engine stumbles and cuts out, air bubbles visible in transparent fuel lines
Vehicle Weaknesses 7
Front strut towers corrode and can break away from the bodywork. Safety-critical failure — affected parts are riveted.
W202 strongly prone to through-rusting at sills, wheel arches and door lower edges. Absence of factory sealant up to 1997 accelerates corrosion. Strut top rust is safety-critical.
Front control arms trap water in internal cavities. Blocked drain holes lead to internal rust. In extreme cases the wheel can detach from the control arm — safety-critical.
Rust on door edges, sills, wheel arches and under door seals. A faulty primer-bath process encouraged early rust formation. First build years particularly affected.
Rubber bushes in the front wishbones wear and develop play. Anti-roll bar mountings wear noticeably quickly.
Wiring breaks affect electric seats and steering column stalks. Classic ageing problem from brittle cable insulation.
Window regulator control units fail through water ingress. SAM module controls lighting and wipers — failures typical on older W202.