Mercedes-Benz G 320 CDI
V6 diesel with common rail and piezo injectors. Powerful and refined. Known for blocked oil coolers, swirl flap failure and EGR problems. High mileages possible with good maintenance.
Diesel Off-Roader
Solid diesel in the G with 165 kW. Pragmatic and off-road capable, driving fun is secondary.
Engine Weaknesses 7
The best-known problem of the OM642: the oil cooler gaskets in the V-section of the engine fail. Oil leaks into the coolant or externally. Particularly prone on vehicles built up to 2009.
Symptoms: Oil loss warning, oil spots under the left side of the vehicle, oil streaks visible on the belt tensioner
The plastic linkages of the swirl flaps in the OM642 intake manifold break. Aluminium repair kits are available and more durable. In the event of complete failure there is a risk of debris entering the engine.
Symptoms: Engine warning light, fault codes for intake flap/swirl flap, power loss particularly at low rpm
Piezo injectors seal poorly from heat, diesel enters the engine oil. Oil loses lubrication properties, tar-like residue around injectors is the typical telltale sign.
Symptoms: Rough idle, increased fuel consumption, knocking noises, oil level rising due to diesel contamination, engine oil smells of diesel
Variable turbine geometry actuator linkage seizes due to soot deposits. Engine enters limp mode. Fault codes P0404, P2598, P2385. If runner damage occurs, turbo costs from €1,300.
Symptoms: Sudden power loss on kickdown, limp mode, black smoke, engine oil in intercooler area
The standard oil pump delivers insufficient pressure at high revs and temperatures. No warning in the cockpit. Connecting rod bearings wear unnoticed between 150,000–200,000 km, total engine failure looms.
Symptoms: Cold knocking at idle, metallic rattling during load changes, fine metal particles in oil filter, oil pressure drop only measurable late
With frequent short-trip driving the EGR system on the OM642 becomes heavily coked. Soot deposits in the intake manifold significantly reduce airflow.
Symptoms: Power loss particularly under load, poor throttle response, soot clouds, elevated fuel consumption
Thin-walled glow plugs corrode in the cylinder head and break during removal. Broken heating element requires time-consuming drilling out. Replace all 6 plugs preventively.
Symptoms: Difficult cold starting, extended pre-glow time required, glow indicator flashes, white smoke at cold start in winter
Vehicle Weaknesses 7
The W463 rusts structurally at window frames (not painted inside from the factory), lower door edges and sills. This problem runs through all model years up to 2018.
The steel ladder frame corrodes at spring seats and cross-members. The double-shell construction is insufficiently sealed and traps moisture.
Window frames are not painted on the inside from the factory and rust heavily. Tailgate and frame sections rust due to missing factory treatment. Full rust treatment up to 7,600 EUR.
Shock absorbers, springs and track rod ends wear out prematurely due to off-road use and the vehicle's high weight.
Worm gear in the steering box shows highest wear in the straight-ahead position. Steering levers and track rod ends are disproportionately often flagged at inspection.
ECU failures often only fixable by complete replacement. Older vehicles with moisture in the engine bay particularly affected. Specialist workshops offer cheaper repair options.
Moisture frequently enters headlights and tail lights, causing short circuits and bulb failures. Tail lights with poor factory sealing are particularly affected.