Mercedes-Benz G 400 CDI
Mercedes' first V8 diesel in automotive history — world premiere in 2000. Common rail at 1,350 bar, two turbos in tandem, 4.0 litres. Result: 570 Nm from 1,600 rpm, a character that no petrol engine of that class could match in composure at the time. Maintenance-intensive. Timing chain and tensioners are due around 150,000 km — not optional, mandatory. The right-hand turbocharger is the known weakness and will need replacing sooner or later. Injectors and high-pressure pump dislike poor-quality fuel. Oil every 10,000 km, Mercedes approval 229.51 or better — the engine does not forgive cutting corners on lubricant. With thorough maintenance 300,000 km is realistic. None of this is cheap, but anyone who buys a V8 diesel budgets for it.
Off-Road Icon with V8 Diesel — Rare Collector's Piece
Only around 5,000 units built. The G 400 CDI combines unchanged G-Class off-road character with 570 Nm on all four wheels — in the field, on the motorway, everywhere. Maintenance-intensive, hard to find, irresistible to the initiated.
Engine Weaknesses 6
Timing chain stretches from around 150,000 km; chain tensioner and guides wear. Cold-start rattling is a typical early warning. Left untreated, chain jump and total engine failure threaten.
Symptoms: Metallic rattling on cold start that subsides after 3-5 seconds. With severe stretch also audible at operating temperature.
The right turbocharger is the classic weak point of the OM628. Total failure of both turbos from around 90,000-100,000 km has been documented. Repair on the V8 diesel is correspondingly labour-intensive.
Symptoms: Significant power loss, blue or white smoke from exhaust, whistling noise under load.
Under extreme pressure loading, head gaskets fail. CO2 enters the cooling system; increased pressure pushes coolant out through the expansion tank. Engine removal required for repair.
Symptoms: Coolant warning light, coolant overflows from expansion tank, coolant level drops continuously.
Common rail injectors are prone to leaks at copper sealing rings and retaining bolts at high mileages. Injector failure can cause secondary engine damage.
Symptoms: Soot trails, rough running, power loss, fuel smell in engine bay. With advanced damage: starting difficulties.
The rear crankshaft oil seal between engine and gearbox leaks at higher mileages. The gearbox must be removed to replace the seal -- a labour-intensive job.
Symptoms: Oil puddle under vehicle centre to rear, oil film visible between engine and gearbox bell housing.
Recirculated exhaust gases coat the intake manifold, inlet ports and mixing housing with up to 2 cm of soot. Fuel consumption rises measurably; power drops gradually.
Symptoms: Gradual power loss, increased consumption, occasional lurching at part throttle.
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.