Mercedes-Benz C 280
Inline-six with four-valve technology. Solid, long-lived engine with good refinement. Keep to regular cambelt change intervals.
Inline-Six That Sings and Pulls
The M104 3.2L inline-six is the soul of the W202. Silky rev build-up, perfect balance, genuine driving character — no automatic can fully ruin that.
Engine Weaknesses 7
The M104 head gasket fails at high mileage. Coolant enters the cylinders or the oil. Repair requires removing the head and resurfacing.
Symptoms: Coolant loss without visible leak, white exhaust plume, mayonnaise on oil cap, rising coolant temperature
The hydraulic chain tensioner on the M104 leaks oil at the timing chain housing. The leak causes oil loss and can cause chain rattling if it fails.
Symptoms: Oil spot at front of engine, brief rattling after cold start, dropping oil level
The M104 inline-six carries a conventional ignition distributor on the exhaust camshaft. Cap and rotor wear out, cracks in the distributor cap cause arcing in wet conditions.
Symptoms: Stumbling under load, misfires in wet conditions, poor cold-start behaviour, rough idle at cold start
The KE-Jetronic fuel injection of early M104 variants (300E, 300CE) suffers from ageing of the fuel distributor and electro-hydraulic pressure regulator. Replacement parts are barely available.
Symptoms: Poor warm-start behaviour, rough running above 80°C coolant temperature, over-rich mixture, sooty spark plugs
The M104 hydraulic lifters lose oil pressure during extended standstill and clatter after cold start. Usually gone after 30–60 seconds; with persistent clattering replacement is needed.
Symptoms: Ticking clatter directly after engine start, disappears after warm-up, permanently audible when worn
The valve cover gasket on the M104 inline-six hardens with age and starts leaking. Oil drips onto the exhaust manifold causing smoke. Simple repair.
Symptoms: Oil smell from engine bay, smoke on hot engine, oil spots on side of engine
The crankcase ventilation rubber hoses on the M104 harden after 20–30 years and crack. False air enters the intake tract, oil mist contaminates the throttle body.
Symptoms: Rough idle, oil deposits on throttle body, increased oil consumption, oil pushed out of the dipstick tube when the system is blocked
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.