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Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 20368
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Im thinking of buying a Mercedes S55 turbo registered in

Customer Question

I'm thinking of buying a Mercedes S55 bi turbo registered in 03. Are there any issues I should be aware off?
Or would a S500 be a better bet?
Submitted: 2 years ago.
Category: Mercedes
Expert:  Matt replied 2 years ago.

What to watch out for

MB have been resisting claims for rusting bodies and bubbing paint under this warranty.

Sadly no RHD versions of the brilliantly surefooted S500 4-Matic four wheel drive.

Not a lot of boot space for such a big car.

Huge options list could increase new price considerably, and spec needs to be checked carefully when buying second-hand.

There may be a problem with the engine mounts of older S320CDI diesels and has been criticism of false alarms from dashboard oil light.

Tinkling sound which rises with revs on 320CDI is from ceramic matrix of catalytic converter.

7-speed G-Tronic with smaller engines can hunt badly at half throttle cruising.

3.0 V6 320CDI is not as economical as previous 3.2 straight six 320CDI.


Niggling build-quality problems on first generation cars. Make sure every electic/electronic gizmo works as it should.

If it's an import you don't get the same warranty so should allow for that and lower resale values in what you pay.

VITAL to keep ventilation plenum chamber drains clear of debris, or water overflows wetting carpets, vent blower motor and wiring loom causing shorts and sometimes necessitating a new loom. (The ventilation plenum chamber is the well in the bulkhead beneath the grille in front of the windscreen through which fresh air enters the car. It's open to the elements, so rainwater should flow freely through it, but won't if the drains either side are blocked. If that happens the rainwater will have nowhere to go except into the car.)

If buying used, CHECK ALL ELECTRICS and feel for damp front footwell carpets.

Rust is a big problem with these cars. Mobilo 30 year warranty against perforated bodywork states "From the 5th year onwards the car should have been serviced by an authorised Mercedes Benz workshop within the last 2 years prior to the damage being repaired". If not attended to, expect perforated rear wheel arches, door bottoms, etc.

Cars fitted with self-levelling suspension are prone to running down their batteries after a long ferry trip or after being left parked for a prolonged period in windy conditions because the system attempts to compensate for movement of the ship or being blown by the wind.

Locking system prone to failure. Cure may be to replace the EIS control unit. Typical cost:- part £309, labour £127.50, VAT £76.39, Total £512.88.


'Straight 6' 3.2 litre CDI engine had a common problem with premature injector failure at as little as 60,000 miles. Replacement injectors are about £300-£400 each, plus fitting and calibrating to the ECU - an expensive repair if they all need replaced at about the same time. Another common problem with the earlier engine is apparent failure of the injector 'fire seals', which allows soot and carbon to basically 'weld' the injector into the cylinder head. If a faulty injector cannot be removed then the cylinder head would have to be replaced.

Another common fault of C-class and other Mercedes diesels is failure of injector seals, allowing fuel/air mixture to be deposited as carbon on top of the engine. The problem can be identified by the smell of neat fuel (like paraffin) entering the passenger cabin, and a "chuffing" sound from the top of the affected cylinder as gas escapes on the compression stroke. Apparently it is so common it has been given the name "black death" within the Mercedes dealerships. Unless spotted early, and seals reground and replaced, the cost of fixing can be up to £500


Circuits are not protected. So if the alternator overcharges, it can send a spike through the ECU and up to 7 SAM units in series and it can be a matter of replacing them one by one to find out which have fried and which have not. An alternator overcharge can also open circuit the starter motor so it doesn't turn off when the engine starts. And can spike the engine temp sensor on the basis of which the ECU decided the fuelling. The cost of fixing all this at MB rates can easily exceed the value of the car.


Rear air suspension highly prone to collapse and if this happens the cost of rectification is usually far greater than the value of the car.



8/8/2000: 780 new S Class built 1/2000 to 5/2000 recalled because water from plenum chamber can cause a short circuit which could result in the heater blower motor regulator overheating which could lead to charring and smouldering. Blower motor regulator units to be replaced. But the culprits are the plenum chamber drains.

16-11/2005: The National Highway Traffic Safety Administration (NHTSA) has begun an investigation into recent versions of the Mercedes-Benz S-Class for a potential problem with the vehicle's gauges. The Associated Press reports that the S-Class sedans from the 2000 and 2001 model years are the subject of complaints to the NHTSA that their speedometers and fuel gauges have failed to light. Seven complaints have been logged with the agency, and 72,000 S-Classes are being investigated for the problem, which could become a full recall if the agency determines the problem to be a flaw in the vehicle's design.

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