Mercedes-Benz R 500
Large-displacement naturally aspirated V8, second generation with variable valve timing on all four camshafts. Technically related to the M272 V6 — shares its known balance shaft sprocket problem on build years before 2007 (engine number below 088611). From that number the sprocket was made of hardened steel. Check early engines for fault codes P0016/P0017 and cold-start chain noise. The 5.5-litre with 285 kW is the typical variant; the 5.0-litre with 225–250 kW is somewhat more forgiving in heavier vehicles. The M278 BiTurbo successor is more efficient and more powerful, but sounds considerably less characterful — the M273 is the last true naturally aspirated V8 from Stuttgart. Pre-purchase: always check for camshaft adjuster leaks (oil in wiring harness) and thermostat fault P0128. Oil changes every 10,000 km with MB 229.5.
R 500 5.5 — Lots of Engine, Little Emotion
285 kW in the R-Class high-roof van is more emergency reserve than source of pleasure. The interior isolates the engine acoustically to perfection — V8 feel virtually nil. On the other hand: fully loaded motorway overtaking has barely a calmer companion. As a long-distance transporter for large families barely equalled. Perfectly powered, no emotions.
Engine Weaknesses 9
The M273 V8 shares the balance shaft sprocket issue with the M272 V6. The soft composite material of the sprocket wears down, causing timing chain rattle.
Symptoms: Fault codes P0016/P0017, chain rattling, rough idle, power loss
As with the similarly-designed M272, the solenoid valves leak. The V8 has 4 per bank — consequential costs are particularly high due to more solenoids. Oil migrates by capillary action all the way to the ECU.
Symptoms: Check engine light with camshaft fault codes P0014/P0015/P0021/P0025, lambda sensor failures, in extreme cases ECU failure
Like the M113, the valve cover gaskets on the M273 V8 become porous over time. With a V8 having two cylinder heads, the workload doubles.
Symptoms: Oil spots under the vehicle, oil smell after hard driving, oily engine bay
Identical to the M272: plastic linkages on the variable intake flaps become brittle and break. Fault code P2006 is typical.
Symptoms: Check engine light with P2004–P2006, minimal power loss at certain rpm
The 3-disc thermostat on the M273 V8 fails prematurely in the open position. On motorway driving coolant temperature drops to 75–86°C. Difficult to access in the V8 engine bay.
Symptoms: Coolant temperature fluctuates between 75–102°C depending on load, engine does not reach operating temperature in cold conditions, fault code P0128
The M273 V8 frequently shows sporadic misfires from aged ignition coils. Water in the plug well through porous seals accelerates failure.
Symptoms: Hesitation on acceleration, rough engine running, fault codes P0301–P0308, check engine light flashes with heavy misfires
As mileage increases the M273 V8 shows noticeable oil consumption. 32 valve stem seals wear simultaneously. Above approx. 0.5 L/1,000 km intervention is needed. When doing the balance shaft repair, renew seals and rings at the same time.
Symptoms: Blue smoke on cold start or after long overrun phases, dropping oil level between service intervals, oil consumption above 0.5 L/1,000 km
The throttle body is prone to heavy carbon buildup from approx. 120,000 km. Idle hesitates and vibrates, throttle response lags on load changes. Cleaning is possible but requires a basic adaptation with a diagnostic tool.
Symptoms: Rough idle at operating temperature, slight hesitation on pull-away, engine revs unevenly after cold start, occasional stalling
Engine mounts fatigue and no longer adequately dampen V8 vibrations. Noticeable vibrations in the interior and at the steering wheel around 1,800 and 2,400 rpm. Test: blip the throttle at idle — more than 4 cm of engine movement indicates mounts are due.
Symptoms: Noticeable vibrations at 1,800 and 2,400 rpm, dull droning in the passenger compartment, visible engine rocking when blipping the throttle at idle
Vehicle Weaknesses 7
The Airmatic air spring bellows develop leaks and cause the vehicle to sink. The vehicle sits lower on one side when parked. Arnott replacement bellows approximately €200; workshop costs up to €1,900.
The 7G-Tronic gearbox does not pair well with diesel models; gearbox calibration is rough. At higher mileages torque converter defects occur; 3rd and 4th gear clutches burn out. Gearbox oil flush every 60,000 km recommended.
The Airmatic air suspension compressor wears at high mileage, particularly if the air spring bellows were already leaking and the compressor had to run continuously. Replacement compressor €400–700; expensive to fit.
Design-related water ingress into the boot or footwell damages connectors. Rear SAM control unit costs approximately €1,100 and fails when wet.
Rust appears on doors and black-painted chassis components. First two model years (2005–2006) particularly prone. Improved from 2008/2009 onwards. Avoid early vehicles if possible.
Doors and tailgate show rust perforation even on younger examples. Water ingress via defective seals promotes corrosion from the inside. Body shops quote €1,500–3,200.
The sunroof motor and gearbox skip and jam. Weak on-board electrical system due to battery problems. Steering knocks from worn joints. Wind noise from poorly seated seals.