Buying review Mercedes Benz S-Class (W140) 1991-1998 Common Issues Engines Inspection

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Hello everybody, welcome at the buyers review of the Mercedes Benz s-klass. Internal code W140. This s-klass was nicknamed “Der Kathedral` which means like Cathedral mainly because of it enormous size.

Development on the car started in 1981 so 10 years before its introduction. Mercedes also took its time to develop a v12 engine and high performance breaking system to be incorporated into the s600 top of the line S-class. The first prototypes were built in June of 1990.

The car was built by Mercedes between 1991 and 1998 so this was its flagship car for the 90’s. This was the car of choice for government (Helmut Kohl), captains of industry, dictators and the mob off course, basically all walks of life with a lot of cash and influence. There was even a special model in the form of the s500 landaulet.

The W140 is another classic Mercedes design by Bruno Sacco, more than 400.000 units were built in 8 years, mostly the sedan but there was also a coupe on sale.

The W140 is regarded as one of the most iconic and technological advanced cars ever to be built. This car is now more than 20 years out of production, I think it is time to see if these claims are correct.

So you are thinking of buying one or owning one ?

In 2019 and later that is quite a challenge I would say, I will try to guide you through the process of buying the car and what to look out for.

First off I would like you to know that these vehicles are quite complex, I will point out to the most common reported issues with these cars. Next to them being complicated and complex they are also more than two decades old by now.

First, the question of price. What should you be willing to pay for such a car. Difficult question to answer, it depends on the quality of the car really. Millage is not the biggest problem, these cars were made for thousands of miles of German autobahn. Engines are the most reliable part of these cars.

What you do need to check is what kind of bills there previous owner had, and get a good idea of its service history, especially when you are tempted to buy the V12 engine. Also keep in mind that this engine should be serviced by a specialist. Although these engines are very reliable, if anything goes wrong on them, your car is most cases will be economically bankrupt. In other words, the prices of repairs will exceed the value of the car.

Attention points

The aiconditioning on the pre 1995 models have a evaporator fail, the cause of this was a chemical reaction between dissimilar metals. The plumbing of the evaporator was incompatible. I heared you can have this one replaced with an evaporator of the e-class W124. This problem mostly excist on pre-facelift models.

Secondly the fuel injection harnesses, this afflicts all Mercedes models from 95 to 98. Just keep in mind that the harness of the W140 isn’t cheap, especially on the V12. Most W140 will have its harness replaced by a improved version, if not use this issue as a discount for the car you are buying.

Thirth, these cars are quite heavy, so if the car surpassed the 200.000 KM mark check it the suspension need any work, again service history is vital. See if the previous owner had the suspension replaced or fixed, if not, another way to ask a discount. It is mostly the bushes in the suspension sub frame that wear out simply because of the sheer mass of the car. The bushes themselves are not expensive, but the time it takes to replace them is more of an issue, especially when do by a mechanic.

Forth, this W140 was one of Mercedes first cars to have self-closing doors and a trunk lit, closing of the doors and trunk is done by a computer operated vaccum pump which sits under the rear seats. If the pump breaks this will cost quite some money.

Fifth, Then the ECU’s. These chips are now more than 20 years old and do not have a history of unreliability, but if they break then there could be some performance issues of electrical issues. Check these chips, especially for people that want to buy the V12. The V12 has a total of 7 ECU’s just for the engine, so you are warned.

Sixt, The automatic transmissions, the automatic 5 speeds have know to give trouble in the latter models. Mostly due to the fact there is no recommended oil change interval. These automatics are sealed for life, but in practice it is recommend to flush these automatics once every 100.000 KM and change the oil every 60.000 KM.

Then the last thing, the electric windows motor fails with age, the double glazed windows are very heavy and the motors work hard moving them up and down.

So are you still thinking to buy a W140 or are you scared away ?

If you are afraid of the V12 in terms of costs, you should go for the V8. These engines proved to be very reliable but only under the condition that the oil changes have been done every service interval. The six cylinder are considered under powered for this beast. Also the v6’s engines have been plagued by head gasket failures.

Strong points of the car

Car is seriously over engineered

Very strong road presence

Ultimate interstate or autobahn cruiser, perfect for going from East to West in the states and North to South in Europe. Just bring enough cash for petrol.

In many regards this car still drive better than most modern cars

Few more points, millage is not a big issue. It is better to buy a car that was used for longer highway commutes then a car that spent most its life inside the big city. Again service history is important. And do not buy this car when you are on a budget, it is not an unreliable car but when something breaks, you will be spending premium prices as well. When buying such a car, have a Mercedes specialist check it fist for poper inspection. This car is a potential money pit, but it can also still serve you for many years to come.

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