WHAT TO LOOK FOR

What to look for

There were a number of quality issues with early SL55s.

Some were fine, but others spent a considerable amount of time back at the dealer being fixed. Quality has improved since, but you should examine a car’s history closely.

It is easy to be intrigued by the look of the car when seeing it but if the seller holds back service information, then walk away or you will be heading down a road of poverty.

I recommend you call the dealerships who have serviced the car to gather as much information as possible.

Engines

Engine maladies are very rare. The SL55’s V8 benefited from considerable strengthening over the 500 unit on which it’s based. Almost every moving part was uprated – even the crankcase was strengthened to deal with the significant increases in temperature and pressure.The supercharger sits in the middle of the 90degree V and has proved to be an extremely reliable unit, despite spinning at 23,000rpm and providing 0.8bar of boost.Ensure all fluids are up to the mark and look clean. It’s also worth inspecting the myriad of pipes surrounding the engine for signs of corrosion and leaks (the supercharge- cooler also has its own radiator and associated plumbing). Repairs can be difficult depending on the site of the problem, as access around that whopping motor is tight.

Sorry to say that the M113 has one design flaw. It is the steel chain for the oil pump that at some point will beat the aluminum cover while the engine idles, spewing aluminum metal shavings into the oil. Mercedes Benz has never acknowledged this since the cost will defiantly bring the house down in its knees since fixing this will mean designing and exchange the chain cover – a operation which is one of the most complexes you can undertake on this engine. You can see the problem being addressed her:

M113 DESIGN FLAW

Electrics

In most cases you’ll find that all the electrical systems work perfectly, but there are examples of cars that have had numerous issues. As just about every aspect of the SL55 has an associated electrical system, diagnosing and fixing faults can be difficult. It’s not uncommon for cars to go back to the dealer a couple of times before the problem is resolved. Mercedes-Benz dealers are often a better bet than independent garages for electrical work as they have access to fault information at the Stuttgart factory.Common problem areas include the traction control system, electric windows and the fly-by-wire throttle, but these usually occur early in the life of the car, so should have been resolved by the original owner. The optional ‘keyless go’ and tire pressure monitor systems are known to play up occasionally too.Ensure the recall for the voltage regulator was adhered to – there have been instances of the batteries discharging within a couple of weeks.

Brakes

There were two recalls concerning the Sensotronic Brake Control system, therefore it’s very important to check that the work has been done. The first (July 2004) was a software download enabling the control unit to monitor wear; the second was to check for faulty hydraulic units, which were replaced as necessary.

The big 355mm discs with eight-pot calipers up front are very effective, but also expensive to replace. The braking system is complicated, what with Sensotronic (which claims to provide smoother braking), Emergency Brake Assist and ESP, but it has proved to be reliable. Wear rates inevitably reflect the way the brakes are used, which means you can tell how hard an SL’s previous owners have been driving. Expect to see 20,000 miles for the pads and 30,000 for discs under normal, non-track driving.

The roof

There have been a number of cases where the SL roof system has failed dramatically and catastrophically. It usually happens before 10,000 miles and involves the roof mechanism getting out of sync and collapsing in a heap, necessitating a rebuild.Some roofs have been known to rattle and have problems while operating, but these usually just require realignment. However, be wary of buying an SL with a roof that isn’t perfect, as this can also point to poorly repaired accident damage.The other big problem with the SL roof is that it can leak badly into the boot. This was particularly prevalent in early examples and there was no permanent cure until 2005 (the solution involves the replacement of all the seals). Thankfully this problem is now rare, but you should examine the boot lining carefully for signs of dampness and damage. The leaking also caused the ruin of the pump for the hydraulic to operate the roof since it’s attached to the bottom of the boot – the replacement cost about 1.700€

Fuel tank

A number of cars have had the fuel tanks replaced under warranty due to a failure with the lifter pump. You will hear the problem, as the pump starts ticking when fuel has dropped below three-quarters full. There’s also a baffle plate that comes loose and you will hear it when you take corners. There’s a fix for this – the Mercedes Benz way will take you to see your tank being dropped and replaced for a considerable amount of money … the other fix is a “DIY” – done with a usual hanger – I’m not kidding you.

Suspension

Struts are known to fail, and cost around 1.600€ per corner to fix. For this reason you should ensure that any car you are thinking of purchasing has been examined by an expert. These failures are neither age- nor mileage- related, but will be covered under a warranty - up to a point! Also, there have been cases of the hoses for the ABC system splitting. If this happens you will find a pool of fluid sitting under the car.

Unfortunately Mercedes Benz does not have any intervals for flushing the ABC system or changing the oil which undoubtedly would have reduced a lot of disasters for not so few Mercedes Benz owners.

Running costs

The SL55 has variable service intervals. With average driving (and no track work) you should expect the first service to arrive at around 20.000 km. or two years and cost between 350€ and 400€ depending on the dealer. The slightly larger service that will arrive between 32,000 and 38,000 km. will cost around 600€. Added to this there are also consumables that need to be changed at specific intervals: the brake fluid should be renewed at two years for around 250€, at three years the coolant needs to be replaced for 160€, at four years sixteen new spark plugs will set you back 500€, while the air filter cost 120€ and fuel filter that will put you back for 240€ will need replacing at the same time. Finally, every five years the automatic transmission oil and filter need to be changed to the amount of 300€.

When looking at the prices for a used SL55AMG then it is possible to get some healthy discounts – if you try autoscout24 (European) you will find between 50 to 70 cars for sale starting at around 20.000€ and that’s not mush comparing this car was priced at 120.000€ when new.

I cannot emphasizing enough how important it is to go for a car that have had the maintenance on a regular basis – ells you will not be able to pay your way out of it since these high-end cars have to be treated and nursed for to keep them on the road.

Most Reported

2003 Mercedes-Benz SL55 AMG - http://repairpal.com/mercedes-benz-sl55_amg-2003/problems

Leaks in the pneumatic system will cause problems with the dynamic seats, the trunk, and door closing assist.
The active body control system can leak fluid from numerous areas, including the tandem pump, hydraulic lines, struts, and/or seals. If it is not repaired, the vehicle ride height could drop too low and cause damage to the undercarriage.
The engine may develop a stalling and/or no start condition due to a failed crankshaft position sensor.
Flush brake fluid every two years
Oil Leaking From Oil Level Sensor
Oil may leak from PCV vent housings and inspection plates
On higher mileage vehicles, wear causes noise at the vario roof seals. Lubricating the seals can usually cure the problem; in most cases, the seals do not need replacement.
The early versions of the central gateway module (which allows different systems to communicate with each other) have software problems.
The evaporator temperature sensor can fail, causing the AC compressor not to cycle. If the AC compressor does not cycle on, the AC system will not blow cold air. If the AC compressor is stuck on, the air will be very cold at first, before warming up.
High mileage or older vehicles develop leaks at the differential seals and cover; the whole unit needs to be resealed to repair the leaks.
The rubber bond in the harmonic balancer can decay, which causes the balancer to move and work its way into the timing chain cover. If the balancer comes into contact with the timing cover while the engine is running, it will fracture and damage the timing case and potentially other surrounding parts. The harmonic balancer should be inspected at every service.
Front thrust arm and control arm bushings can crack and sometimes tear completely. If this is not repaired quickly, damage to the front subframe unit will occur, which is very expensive to repair. Updated control arms (that prevent damage to the subframe when the bushings wear out) are available.
A vibration felt through the center floor of the vehicle can be caused by driveshaft flex discs, which crack and shred, causing excessive driveshaft movement. Not repairing these can cause damage to the driveshaft center support bearing, or, in the worst case scenario, damage to the transmission or differential.
The wire connector on the transmission leaks fluid into the wiring harness. If not repaired, the oil will migrate through the wiring harness and damage the transmission control module. A new harness and control module are required to fix the problem.
The ESP and BAS warning lights may illuminate due to a failed brake light switch. Replacement of the failed switch should correct this concern.
This vehicle has sensotronic brake control (SBC). If the SBC light on the dash illuminates, have the brakes checked. If the SBC is not working, limited brake pressure is delivered to the front brakes, increasing the distance it takes to stop. The SBC hydraulic unit has a specific service life programmed into the control module; follow the manufacturer's recommended service procedure for proper maintenance of the SBC.