Mercedes-Benz GLK 250 CDI

Over 100,000 vehicles recalled: the chain tensioner seal leaks, allowing engine oil to drip onto the exhaust system and potentially ignite.

Symptoms: Dropping oil level, oil smell from engine bay, oily deposits under the vehicle, possible oil fire

The OM651 uses a simplex timing chain. With short-trip driving and overdue oil change intervals the chain stretches.

Symptoms: Light rattling noise on cold start from the rear of the engine, no fault code stored

Same Delphi piezo injector problems as in the DE18: 220 CDI and 250 CDI variants affected. Mercedes replaced them with solenoid injectors as part of a service action.

Symptoms: Vibrations and rough running especially under acceleration, elevated fuel consumption

The EGR cooler of the OM651 develops hairline cracks at the connection stub and loses coolant. Green staining next to the fuel filter under the engine cover is typical.

Symptoms: Dropping coolant level without visible leak, intermittent coolant warning, green spots under the vehicle, heater output diminishing

The DMF on the OM651 suffers under the high torque output. Documented case: all 8mm rivets sheared at 149,000 km, with consequential damage to the clutch and crankshaft speed sensor.

Symptoms: Rattling and juddering at warm idle, vibrations when pulling away, shuddering at low RPM, noise increases with warm engine

From around 150,000–180,000 km the OM651 turbocharger leaks oil through worn bearings, which drips onto the EKAS intake port deactivation actuator and destroys it. Double damage.

Symptoms: Black smoke under acceleration, oil residue in charge air hose, power loss, fault code P0299 boost pressure underrun

OM642 diesel oil cooler tends to develop leaks at high mileage. Oil traces under the gearbox are a warning sign. Repair requires 7 hours of labour through complete disassembly.

Internal corrosion forms inside the hollow profile of the rear axle carrier behind the rubber mount. Structural integrity at risk with advanced infestation. Mercedes frequently covers repair under goodwill.

Brake lines corrode at line brackets where dirt and salt accumulate. Replacement requires lowering the rear axle, possibly also the fuel tank. Workshop costs 220–2,000 EUR.

Handbrake seizes when not used regularly. Brake lines corrode with age. Brake problems increase with vehicle age. Brake pads wear quickly on petrol models.

GLK is heavier than the related W204, resulting in higher wear on suspension bushings. Front control arm and anti-roll bar mounts particularly affected. Xenon headlight brackets vibrate.