Mercedes-Benz AMG SL 55
Naturally aspirated V8 in three displacements from 4.3 to 5.5 litres — old-school character with no turbo lag. Linear power delivery, deep rumble from 2,000 rpm building to a hoarse roar above 5,000. Peak torque at 3,000; beyond that it thins out — yet it's silky in part-throttle and surprisingly economical. Achilles heel is the seals: rear crankshaft oil seal practically universal above 150,000 km (gearbox removal required, 600–900 EUR), valve covers and oil filter housing seep with age. All cheap parts. The one critical point: the rubber damper on the crankshaft pulley hardens with age — when it fails the pulley machines into the sump. Replace preventively every 150,000 km. Oil changes every 10,000 km with 5W-40, 16 spark plugs every 60,000–80,000 km — then 400,000 km is realistic.
517 hp NA Crown — Strongest M113 in a Roadster
Strongest variant: 517 hp without forced induction. Above 5,000 rpm the sound becomes metallic-sharp, almost like a racing engine. Vario roof down, third gear, full throttle — that is naturally aspirated V8 in its purest form. Against the supercharged SL55: less brutal, but more linear and emotional in the high-rev range. ABC suspension and brakes as running costs; engine virtually indestructible.
Engine Weaknesses 10
The rubber damper in the crankshaft pulley hardens with age and can eat into the sump — catastrophic consequential damage. Preventive replacement every 150,000 km strongly recommended.
Symptoms: Unusual vibrations at idle, in worst case metallic scraping from below. Often no prior warning — sudden failure.
The rear crankshaft seal is leaking on virtually all M113 engines above 150,000 km. Gearbox removal required — 600–900 EUR workshop costs. If oil creeps into the torque converter it becomes expensive.
Symptoms: Oil drops or oil film visible at the engine-gearbox interface, oil loss without any other apparent leak on the engine.
Engine mounts can fail before 100,000 km. Practical test: finger between the stabiliser bar and front sump — no clearance means the mount is dead. Not visually checkable without removal.
Symptoms: Vibrations in interior especially at idle, dull rumbling on acceleration, in worst case contact between engine and bodywork.
Faulty thermostat leads to permanently low engine temperature (increased wear) or overheating in traffic jams. Part costs 24 EUR — swap it immediately on suspicion, do not wait.
Symptoms: Temperature gauge permanently below mid-point (thermostat opens too early) or engine overheats in traffic (thermostat stuck closed).
The front crankshaft seal hardens with age. More accessible than the rear seal, but the pulley bolt is a single-use part. Oil on the drive belt damages it additionally.
Symptoms: Oil film on underside of belt drive, oil visible on drive belt.
Both valve cover gaskets harden with age and allow oil through. Cheap parts (18 EUR each), but caution: aluminium bolts on the valve cover — no over-torque or the threads strip.
Symptoms: Oil smell in engine bay, visible oil film on lower valve cover edge, smoke when oil drips onto exhaust manifold.
PCV hoses become brittle and crack. Leads to pressure increase in the crankcase, elevated oil consumption and false air ingestion. All hoses together under 31 EUR — worth replacing as a set.
Symptoms: Elevated oil consumption without visible leak, white smoke from exhaust, idle fluctuations from false air.
O-ring seals on the oil filter housing and oil cooler connection harden and seep oil. Classic ageing, cheap to fix if caught early — all three seals under 30 EUR.
Symptoms: Oil film around the oil filter area, drips under the vehicle at the front of the engine.
The bolts on the intake manifold switchover loosen. They cannot fall out but cause noise and functional disturbance. Recommendation: remove intake tract, clean, secure bolts with Loctite.
Symptoms: Clattering or rattling from the intake area, irregular throttle response, slight power drop at certain rpm.
The 16 original injectors (black) wear at high mileage. Mercedes introduced revised blue injectors. O-ring seals on the injectors can leak and allow fuel into the oil.
Symptoms: Elevated fuel consumption, idle fluctuations, fuel smell on dipstick from leaking O-rings.
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).