Mercedes-Benz W 126 S-Class Buying guide

In 1979 the Mercedes-Benz W 126 S-Class entered a new era with a more lightweight and restrained look. The modern but never fashionable model series has long established itself as a classic.

For a better understanding of the Mercedes-Benz W 126 S-Class in the early 1980s, it helps to take a brief look back to the 1970s: the automotive world was preoccupied by the oil crisis with its fuel shortages and rapid price increases, and there was a general move towards lower fuel consumption. A sustainable future was only possible with due regard for the environment.

This defined the constraints within which the engineers had to develop a new flagship model for Mercedes-Benz. Firstly, it was necessary to defend the claim to leadership in the luxury class: solidity and comfort, size and safety were therefore indispensable key parameters. Secondly, however, the new S-Class was to be lighter, more economical and aerodynamically progressive – conflicting aims that had to be reconciled at Mercedes-Benz level.

The result, introduced as the W 126 series in 1979, was all the more impressive as it attracted even more customers than its predecessor. Even at that time, computers calculated precise material thicknesses and reinforcements to save weight. New materials including high-strength steel alloys were used, and on conclusion of the development work the bodyshell was around 100 kilograms lighter than that of the predecessor – and provided even more passive safety. The new light-alloy engine blocks and practically all other components likewise weighed in at far less. This rigorous engineering discipline was also to be reflected by the impressive exterior.

Under the aegis of chief designer Bruno Sacco, the result was a decidedly modern but sober design with visibly less chrome trim except for the radiator grille, window frames and a few details. All in all, the Mercedes-Benz W 126 S-Class made a much smoother, stretched impression, which was accentuated by the side rub strips of ribbed plastic. Although they initially met with a certain amount of criticism, these elements – which have long been colloquially known as “Sacco boards” – are now admired as features typical of their time. They never hampered the career of the 126 series: around the world, this second edition of the S-Class was also easily the top seller in the luxury class, and is still seen as an impressive sales success to this day.

Market value of the Mercedes-Benz W 126 S-Class

Only a minority of the more than 818,000 examples of the S-Class Saloons delivered worldwide have survived in good condition, but the overall number seems large enough to keep the market lively. There was also an enormous variety of models: alongside the long and short versions, the engine variants ranging from the 260 SE, 122 kW (166 hp) to the muscular 560 SEL, 220 kW (300 hp) offer a wide choice of different characters. Plus there are the equipment options: the models with smaller engines in particular tend to have plainer standard equipment, while the top models are lavishly equipped. Market prices are correspondingly wide-ranging – even in condition 2, six-cylinder models can occasionally be found for under 10,000 euros, while well-documented, generously equipped V8 variants can cost twice this amount, or even considerably more in individual cases. However, the enormous value increase of around 50 per cent in recent years has also attracted less reputable sellers who are offering condition 4 examples at totally inflated prices.

Body

Compared with previous model series, Mercedes-Benz established a new level of corrosion protection with the W 126. Their bodyshells are even more robust and durable than those of the predecessor series, and some of their weak points are reasonably accessible and can also be easily checked by the non-professional. Nonetheless, the early models from this series are now almost 40 years old – time enough for rust to eat its way into the body panels. Whether a repair is worthwhile can only be decided from case to case.

One of the most critical areas of the Mercedes-Benz W 126 S-Class is the lower panelled area around the large rear window. The cause is aggressive ultraviolet radiation: this section is often subject to massive solar exposition over the years that weakens the rubber components. Moisture event ually penetrates and deterioration begins, undetected by the owner. If rust or a milky patch in the glass is already visible from the outside, the process is usually well advanced. Earlier stages can be recognised on inspection from the boot, where a torch and a mirror prove enormously helpful.

An equally thorough inspection should be given to the frame components around the front suspension. Rust can also develop undetected here: it migrates under the original underbody protection. Rust can also be concealed beneath the “Sacco boards”, though this can only be made visible by removing them. It is easier to take a look at the recesses on either side of the boot floor, which are also critical areas. It is also a good idea to look carefully for hidden signs of accident damage.

Engine and transmission

The Mercedes-Benz W 126 S-Class models are undoubtedly very durable: many examples have covered hundreds of thousands of kilometres, usually without any major problems. Accordingly, W 126 models with very low odometer readings are nowadays rarely encountered in the market. However, the mileage alone should not be a key criterion if the longlived engines have been well maintained: the critical areas for wear are the timing chains with their slide rails, and the shaft seals and guides of the valves. The injection nozzles and hydraulics should also be replaced over the course of the engine’s long life. If the previous owner has already done this, corresponding documentation should be available as evidence.

Another criterion is the condition of the camshafts and cam followers, especially in the V8 engines, and the mixture control unit of the KE-Jetronic can develop leaks. Generally speaking, engines and transmissions with excessively oily surfaces should at least give cause for concern. However, a slight exudation of oil is not a reason for downgrading. The differentials are particularly susceptible to this.

The fact that low mileage not only has advantages is confirmed by the automatic transmissions, which were only standard equipment for V8 models. These wear much more rapidly in short-distance operations than on long motorway journeys.

A quietly and smoothly shifting automatic transmission is therefore a definite plus. It is always a good idea to check the fluid levels of the transmission and differential. Many potential buyers neglect this, as it involves a degree of effort.

Interior

Most Mercedes-Benz W 126 S-Class models were upholstered in fabric as standard; upholstery in leather, velours or the highly robust MB-Tex was available as an optional extra. However, the seat structure is no less important than the condition of the upholstery. The usually much more frequently used driver’s seat can show signs of weakness, especially when compared with the less-used front passenger seat.

The exotic wood facings often have cracks in the varnish. This is not too much of a problem for experts. If the layers of veneer have separated from their metal backplates, however, the cost and effort can be greater. Suitable replacements are very hard to find.

Instruments and operation

Mercedes-Benz has always attached great importance to easy, functional operation. The luxuryclass models also dispensed with unnecessary fripperies – and thoroughly: easily comprehensible switches, clearly legible instruments and outstanding climatic comfort always ensured a pleasant journey for enthusiasts of vehicles with the three-pointed star.

The control stalk on the left behind the steering wheel was no exception in this regard. This feature allowed the windscreen wipers, turn indicators and headlamp flasher to be operated very easily. It is normally not particularly susceptible to faults, but should nonetheless be checked.

The same applies to cruise control, if included. If this system does not work perfectly, the fault usually lies with the control unit – the cruise control system is fitted with its own processor, which can normally be repaired given sufficient expertise.

Another annoying problem is if the ABS and ASR warning lamps fail to go out as they should after the engine is started.

Fortunately, the systems themselves only very rarely malfunction. Faults here are due to an insufficient onboard voltage, which can easily be remedied by overhauling the alternator. Defective wheel sensors can also occasionally be the source of the fault.

Wheels and suspension

Most Mercedes-Benz W 126 S-Class models are now fitted with light-alloy wheels. The data card indicates whether a feature has been delivered as an optional extra. If the wheels are retrofitted, approval of their size should be verified. The wider the tyres, the more quickly the suspension components will wear, especially at the front. The necessary parts are available; however, the need to replace supporting joints, tie rod ends, brake supports or steering arm bearings should be included in the calculation, as the technical effort involved is quite considerable.

Buyers should also be cautious if there is excessive play in the steering when driving. The steering gear is often at the limit of its adjustability and also tends to lose oil. This makes an expensive replacement necessary.

If well maintained, the high-performance brakes of the W 126 make for deceleration that is still impressive today. However, after extremely heavy braking the front brake discs may become slightly deformed, which could lead to brake shudder. Fitting new discs will resolve this problem.

The hydropneumatic system is an extremely comfortable but now also somewhat feared optional extra. It guarantees ride comfort at the highest level, but is enormously cost intensive if faulty.

Special considerations

Radios are one of the most popular discussion topics among equipment experts. The most expensive unit for the W 126 series, the very easily operated “Becker Mexico Compact Disc Electronic Full-stereo”, was priced at just under 4,400 deutschmarks in the final year of production. A remote control unit and a sound system could also be ordered. Also fascinating today is the once prohibitively expensive mobile phone technology: in 1990 a C-network mobile telephone cost around 7,750 marks, plus the installation kit, aerial and hands-free system. Customers wanting or having to make phone calls in their W 126 first had to spend more than 10,000 marks on hardware.

One compensation being, that at the gear is often at the limit of its adjustability and also tends to lose oil. This makes an expensive replacement necessary. If well maintained, the high-performance brakes of the W 126 make for deceleration that is still impressive today. However, after extremely heavy braking the front brake discs may become slightly deformed, which could lead to brake shudder. Fitting new discs will resolve this problem.

The hydropneumatic system is an extremely comfortable but now also somewhat feared optional extra. It guarantees ride comfort at the highest level, but is enormously cost intensive if faulty. launch of the first W 126 in 1979, the necessary technology had been even more expensive.

The electric window regulators (2 or 4), which were initially only available as standard in the 500 SEL, tend to function reliably over the long term. Failure of a power window is often due to worn slide shoes, which are expensive to replace – especially in relation to the cost of the parts. Another feature to check is the central locking system, which was initially only standard for the 500 SEL. This operates on the vacuum principle, not electrically, so even the slightest leaks in the system will lead to failure. Identifying the cause can be expensive, as it involves a great deal of disassembly and reassembly work.

Mercedes-Benz W 126 S-Class Models

Mercedes-Benz started the 126 series with a classic in 1979: the success story of this second S-Class began with the 280 S (carburettor engine) and 280 SE. In January 1980 the 380 SE and 500 SE followed as the first eight-cylinder models. The newly designed engines saved considerable weight with their light-alloy engine blocks. In 1981 Mercedes-Benz modified some of the engines, but the great departure only came with the W 126 model facelift in late 1985: the entry-level model was now called the 260 SE, while the 300 SE added a six-cylinder variant. The V8 category was now represented by the 420 SE, 500 SE and 560 SEL. The diesel models were reserved for export to the USA. From June 1980 onwards, customers with higher expectations of comfort and spaciousness could also order a long-wheelbase version of the W 126, which was 14 centimetres longer and bore the suffix SEL – only the 280 S and 260 SE never became available with this extra space. The standard equipment of the S-Class was also extended over its production period: ABS as standard was introduced in the autumn of 1984 for all vehicles with eight-cylinder engines, and in 1986 for all six-cylinders.

MODELS

260 SE
Vehicle data
Displacement 2,599 cc
Output 122 kW (166 hp)
Top Speed 200-205 km/h
Built between 1985–1991

280 SE
Vehicle data
Displacement 2,746 cc
Output 136 kW (185 hp)
Top Speed 210 km/h
Built between 1979–1985

300 SE/SEL
Vehicle data
Displacement 2,962 cc
Output (with cat. conv.) 132 kW (180 hp) (without 138 kW (188 hp)
Top Speed 205 km/h (without 210 km/h)
Built between 1985–1991

420 SE/SEL
Vehicle data
Displacement 4,196 cc
Output 150-160 kW (204-218 hp)
Top Speed 210 km/h-220 km/h
Built between 1985–1991

500 SE/SEL
Vehicle data
Displacement 4,973 cc
Output 170–195 kW (231–265 hp)
Top Speed 220–235 km/h
Built between 1980–1991

560 SE/SEL
Vehicle data
Displacement 5,547 cc
Output 200–220 kW (272–300 hp)
Top Speed 225–250 km/h
Built between 1985–1991

300 SDL Turbodiesel
Vehicle data
Displacement 2,996 cc
Output 110 kW (150 hp)
Top Speed 195 km/h
Built between 1985–1987

350 SD /SDL Turbodiesel
Vehicle data
Displacement 3,449 cc
Output 100 kW (136 hp )
Top Speed 175 km/h
Built between 1990–1991

Mercedes-Benz W 126 S-Class Clubs

Mercedes-Benz Interessengemeinschaft e.V.
Im Hang 16, 52428 Jülich, Germany, www.mbig.de

Mercedes-Benz S-Klasse-Club e.V.
Feldmarkweg 31, 58093 Hagen, Germany, www.s-klasse-club.de

W 126 Club Deutschland
Joachim Weiand, Auf den Steinen 17, 65599 Dornburg, Germany, www.mercedes126.de

Mercedes-Benz W 126 S-Class Books

Heribert Hofner, Mercedes-Benz W126 Die S-Klasse, das beste Auto der Welt, Heel Verlag (2018), € 49.95

Mercedes-Benz S-Klasse Club e.V., Kaufberatung Mercedes-Benz Baureihe 126, Mercedes-Benz S-Klasse Club e.V. (undated), € 15

Mercedes S-Klasse Serie W126 ab September 1979, Bucheli (2012), € 39.90

Hans-Peter Lange, Die 126er Codes – Jetzt entschlüsselt: Die S-Klasse von 1979 bis 1991, MBIG (publisher), antiquarian

A contribution in cooperation with Mercedes-Benz Classic Magazine and Looping Group.

The current Mercedes-Benz Classic Magazine is available for 5.80 EUR per issue or as a convenient subscription. Don’t miss an issue and subscribe here.

Text Thomas Wirth Photos Götz von Sternenfels / Daimler AG

Author: Looping Group

Looping Group is a brand publishing house with the best story tellers on all media with offices in Berlin, Hamburg and Munich. This text was published first in Mercedes-Benz Classic Magazine which is also produced by the Looping Studio Hamburg. More information about the agency on www.looping.group. View all posts by Looping Group →