Mercedes-Benz SL 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.
SL 500 R230 — V8 Roadster of the Classical School
Open, everything changes: with the hardtop down the M273 in the R230 sounds like a proper V8 roadster. 285 kW is enough for a sovereign 250 km/h, the ABC suspension soaks up roads sportingly without becoming harsh. One of very few naturally aspirated V8 roadsters under 30,000 euros. Find one without sprocket damage and with a well-maintained ABC hydraulic system, and the job is done.
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 11
The ABC hydraulic pump can develop cracks and lose pressure from 120 bar down to 60 bar. Suspension can no longer maintain ride height, soft and vague handling characteristics.
The hydraulic fluid absorbs moisture, rubber components decompose and contaminate the system. Valve block and lines develop leaks. Annual oil change prevents major damage.
The SBC unit is designed for approximately 400,000 brake cycles and fails at this point. When it fails, braking effectiveness is severely reduced — a safety risk. Mercedes extended the warranty to 25 years.
The electric motor of the roof pump burns out. Windings and circuit board affected. Pump runs audibly for longer or not at all. Specialist repair from 595 EUR, Mercedes dealer significantly more expensive.
Defective control unit causes functional failures of the vario roof. Roof stops in various positions, headrests raise but do not return.
The electric folding roof develops problems with limit switches and hydraulic components. When the sequence is disrupted, the roof no longer opens or closes.
The R230 develops clicking and creaking noises in the steering rack, often at every third steering input or under load. Track rod ends are a frequent cause. The steering rack can also lose hydraulic oil.
Typical rust spots develop at the tips of the rear quarter panels at the transition to the door and sill. Moisture and dirt collect there. Rust can grow from the inside out and is often only visible at a late stage.
The Vario roof contains 11 hydraulic cylinders. The seals become porous with age; escaping oil damages trim panels and the boot. Seal sets for all cylinders are available for around 99 EUR.
Despite the hardtop, water enters the boot. Porous seals at the interlocking points of the Vario roof as well as blocked drainage channels at the rear screen.
The plastic hinges on the side parcel shelf flaps become brittle after approximately 15 years and snap off. OEM replacement around 1,600 EUR for both sides, a brass repair kit is available for around 90 EUR.
Reports & Tests
275 owner complaints filed with NHTSA (2001–2012). Most reported: Suspension (77), Brakes (73), Electrical (41).