Mercedes-Benz C 250 D
Five-cylinder with swirl-chamber injection, also as turbodiesel. Robust design with good mileage potential. Check turbocharger on TD version.
Inline Five Without Appeal
83 kW from the OM605 — at least it is an inline five-cylinder, but in the C 250 D the punch for genuine fun is lacking.
Engine Weaknesses 7
The 4-valve cylinder head shows increased valve guide clearance at high mileage. Oversize boring requires special tooling; seal kits are no longer regularly available.
Symptoms: Blue smoke on acceleration or after overrun, increased oil consumption, slight ticking from valvetrain
Porous O-rings on the solenoid shut-off valve and defective non-return valves allow fuel to drain back to the tank. After prolonged standing, the system has to be laboriously refilled.
Symptoms: Engine will not start after several days standing, fuel lines to filter empty, long cranking required
The turbocharger on the OM605 (605.960/961) is prone to shaft seal leaks. Engine oil enters the intake system and burns with blue smoke.
Symptoms: Blue smoke from exhaust especially when accelerating after idle, oil in intake pipe, increased oil consumption, power loss
On the OM605, head gasket failure is less common than on the OM602, but fatigue cracks increase from approximately 300,000–400,000 km. The pre-chamber head is sensitive to uneven heat distribution.
Symptoms: Coolant loss, oil film in expansion tank, hydraulic tappet noise at cold start, white vapour from exhaust
Like the OM604 and OM606, the OM605 shares the intake valve stem elongation issue. Special BGA repair tappets (1 mm shorter, approximately €10 each) allow a cost-effective repair.
Symptoms: Difficult cold starting, engine requires multiple attempts in cold weather, rough running until operating temperature, quiet ticking in valve area
The OM605 turbodiesel is heavier than the naturally aspirated version and loads the engine mounts more. After replacing all three mounts the engine runs like new.
Symptoms: Vibrations at idle and low revs, engine visibly rocking, judder when pulling away
The alternator shows regulator and brush problems at high mileage. Regulator replacement approximately €49 (Bosch), complete alternator €100–€200 (aftermarket).
Symptoms: Battery warning light, battery not being charged, voltage drop with high electrical loads
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.