W126 Luxury Sedans
Comfortable, Impressive, and Affordable
A Buyers Guide to the 1979-1991 Standard Gasoline and Diesel and Long-Wheelbase Gasoline Sedans
 
Article by Pierre Hedary
Contributions from Richard Simonds
Photography by Bill Walsh and Courtesy of Daimler Archives

Few luxury sedans survive long enough to become classics, and fewer still are actually affordable by the average enthusiast. The W126-chassis Mercedes-Benz, produced during an impressive 12-year run from 1979 to 1991, is a strong contrast in both respects. Examples that received the care and respect deserved for the size and comfort they offered are still on the road today. In fact, enough of them have survived in excellent condition that they are not only affordable as entry-level classics, but are good values for the person who wants a daily driver that is functional, luxurious, and reliable for the price of the cheapest new econobox.

Background
 
In the years following the furor of Ralph Nader’s 1965 book Unsafe at any Speed, and the 1973 gasoline crisis, automotive manufacturers were challenged to meet increasingly stringent safety requirements, as well as higher standards for fuel efficiency. Mercedes-Benz was then testing an aluminum-block V-8, a high-output (for the time) inline-five turbodiesel, and comfortably selling its twin-cam six in the W116 sedan. The W116 car was well-made, but a completely new design was needed to address climate control, U.S. bumpers, and emissions systems issues, and other small items needing development.
 
In response, the first versions of the new W126 SonderKlasse (Special Class), the 380SE, 500SE, and 280S were delivered to their first European owners in 1979. Two years later the 300SD, a 5-cylinder diesel built on the W126 chassis, and the long-wheelbase gasoline-powered 380SEL were introduced in the United States.
 
The diesel-powered 300SD was an instant hit. Sales took off like a rocket and the model won Motor Trend’s “Car of the Year” award, a first for a big sedan. Extremely well made, the well-optioned 300SDs, often offered in the light ivory color that graced Mercedes-Benz sales brochures, are still a common sight on today’s roads.
The long-wheelbase, gasoline-powered 380SEL did not fare as well; the V-8 produced an anemic 155 horsepower. As smooth as the engine was, the timing chain problems for which it became known didn’t help, and Mercedes-Benz technicians were soon plagued with chain replacements that required removing the entire timing cover and, in many cases, the cylinder heads, which cost MBUSA many warranty dollars.
 
The 380SEC joined the model lineup for 1982, but the 300SD was really the star of the show. The faithful turbo-diesel sedan sold with few updates up to the end of production. Many examples of these cars are still excellent daily drivers.
 
Some owners of gasoline cars took things a bit further. The thriving gray market captivated the imagination of many Mercedes owners and private dealers soon began bringing W126 cars in by the dozen, federalizing and reselling them. A 500SEC? No problem. A 500SEL with full-hydraulic suspension and 240 horsepower? Just across the pond. How about a 280SEL with a smooth, high-revving M110 6-cylinder engine?
 
These gray-market cars, when properly imported and federalized – or often not federalized at all – brought great joy to many Mercedes owners and still do today. When companies such as AMG, Brabus, Schulz, and others joined the customization and performance party, things got even better.
 
In 1985, anti-lock braking systems became standard on the W126 cars, heralding a new era of performance and safety. In that year, the U.S. lineup included the 500SEL, 380SE, and 300SD. That changed in 1986 to include the 300SDL, 420SEL, and 560SEL/SEC. Heavily refined, one of these new V-8 flagships became the car to own if you wanted a big sedan. The 603 turbodiesel engine in the 300SDL, however, suffered from the start with cylinder head issues, and although these were otherwise fantastic cars, the model survived only two years before being removed from sales catalogues. Meanwhile, standard airbags and automatic seatbelt tensioners were added to protect drivers of these increasingly fast sedans.
 
In 1988, the 300SE and 300SEL replaced the diesels, and in 1989, final updates were added to the interiors, cooling systems, and exterior panels. In 1990, the 350SD/SDL joined the lineup, and the last W126 cars were sold in the U.S. during the closing months of 1991.
 
In retrospect, these cars were well made, and many people agree that the W126 was one of the best “modern” Mercedes ever made. The quality of these cars is so high that many perfect examples still exist, and few can dispute the charm, elegance, and practicality these cars still convey.

Reasons to Buy
 

• These cars are reliable, comfortable and safe, making them excellent daily transportation.
• Heating, ventilation, and air conditioning systems are excellent, making them quite useable all year round.
• Drive trains are very robust, whether they are gas or diesel.
• Interiors are hard wearing and many of the appointments, such as electric windows, sunroofs and power seats, are reliable and easy to repair.
• Values are about half of what you would pay for a used and recent S-class, with more car for the money.
• Turbodiesels get excellent mileage, in the high 20s or low 30s.
• Six-cylinder gasoline models are sweet and high revving, almost sports sedans in disguise.
• The W126 is a lovely, eye-catching design with good interior proportions, big trunks, comfortable seats, and excellent visibility.

Reasons Not to Buy
 

• Worn examples that did not receive proper attention abound on Craigslist, eBay, and other websites.
• The cost of obtaining OEM parts and service is still very high.
• Aluminum block V-8s and 6-cylinder models often need cylinder head attention due to head gaskets, oil leaks, or valve guides.
• V-8 models are thirsty and not as fast as one would hope.
• Certain areas on these cars bodies have expensive rust issues.
• Gray-market models may have been poorly federalized.
   

Checkpoints
 

• The seats usually need to be examined – broken springs, worn horsehair pads and torn leather can be unpleasant to live with and expensive to repair.
• Dashboards and wood trim pieces can be expensive to replace.
• Climate control actuators must be checked – the center vents should blow hard on AC, while defrost vents close completely.
• Front suspensions should be checked for ball joint and guide-rod bushing failures. These can be costly to fix.
• 1983 and earlier 380SE/SELs should be checked for a timing chain update. All models should have had (at the very least) their chain guides – if not their chain and tensioner – replaced as needed.
• Oil consumption on V-8 and 6-cylinder models should be checked. The V-8 models begin to burn oil when valve guides fail.
• 300SDLs should be examined for signs of overheating or other symptoms indicating a cracked head. While rare now, many of these cars had cylinder head replacements in the past.
• V-8 engines that need cylinder head work may require engine block heli-coils to fix stripped aluminum threads.
• Diesel-engine conversions to vegetable oil/biodiesel should be approached with great caution because the quality of the conversions and subsequent maintenance varies from acceptable to lurking disasters.
• 350SD/SDLs should have oil consumption monitored before purchase. It helps to check with MBUSA to determine if an engine replacement was performed. Buying any 350 without records and routine maintenance is a gamble.
•  On 300SDs, the AC compressor is the weak link in the climate-control system. If you buy the car with no receipt for a new unit, plan on replacing it in the near future, preferably with the updated unit from Behr.
• The rear windshield can delaminate and rust can start in its lower panel.
• The cheaply made sliding jaws on the rear windows often fail, leading to an inoperative rear window, but this is an inexpensive repair.
• Plastic radiators should be checked for leakage and cracking.
• Airbags should be replaced every 10 years. This is a job that has to be done by an authorized Mercedes-Benz dealer.
   

The Nitty-Gritty
 
If you are a first-time W126 buyer, the car to look for is the 300SD. These cars are known for traveling well over 500,000 miles with no serious problems. They are easy to start in all weather conditions, quiet and reasonably powerful, and good examples are readily available.
 
Once you begin to look at gasoline engines, there are some questions that need asking. On V-8s, the condition of the timing chain and valve guides is critical. Timing chain guides are plastic, and with heat and age, they can fail, leading to a jumped chain.  Head gaskets on the V-8 cars will seep oil, and when it begins to burn off of the exhaust, awful smells arise. Therefore, if you are considering any low-mileage or high-mileage 126 with a V-8 engine, you need to know if it smokes, leaks oil, or has had the valve guides replaced. When these cars run right, they might burn a quart every 1,500 miles or so, and they will usually be very quiet, smooth, and comfortable to drive. A well sorted 420SEL or 560SEL is a hoot to drive.
 
In Europe, a 500SEL was available with four-wheel hydraulic suspension. These creatures are not for the faint of wallet, but handling is beyond anything else Mercedes built at the time. The option was available on some 560SELs, but you’ll have a hard time finding one.
 
While the 300SDL was infamous for cylinder-head issues, most still-running examples have been sorted and the result is impressive – a comfortable and very quick diesel sedan that gets 28 mpg or better, with little noise and no turbo lag. The successor, the 350SD, was known for its connecting-rod issues.
 
The diesels in the 1990-1991 350SD and SDL would leak oil through worn valve guides, and on cold starts, fluid pressure on top of the piston would damage the connecting rods. Additionally, the rods were not strong enough to handle the torque of the big 6-cylinder engine. Poor fuel quality, lackluster maintenance by some owners, and stop-and-go traffic all conspired to damage these engines, marring their reputation. Consequently, Mercedes rebuilt many engines before they solved the underlying problem. This can be a fantastic car when the engine is in good condition or is one of the (documented) rebuilt engines. 
 
When reconditioning interiors, make sure that you use Mercedes-Benz horsehair pads and that the grain of the leather is correct. Many suppliers sell rough-grain leather, which is incorrect for the cars, as well as being less attractive and uncomfortable. Most interior trim is still available from Mercedes-Benz or the leading interior-trim suppliers, though it will be costly.

Other Buying Tips

Although gray-market cars were once frowned upon, these models have come into their own as something different. While their velour interiors are difficult to repair or replace, the high-horsepower Euro engines are fun to push hard, and the Europe-only 280SE/SEL can be purchased with a manual gearbox, making it even more exciting to own.
 
AMG did some wonderful things with bodies and power plants, making the W126 its flagship and attaching twin-cam heads to the V-8 engines. The downside is that dealers in the U.S. won’t have replacement parts for either the Euro or AMG-modified models, so you’ll be dependent on independent shops and other enthusiasts.
 
The best W126 cars are still under $15,000, and as they become more collectable, prices will increase. These cars pay off in the long term, as many owners can attest. Even with the cost of service, these cars deliver more than you put into them, and with reasonable care, are likely to continue to do so for decades.
 
 

We Bought One
by Bill Walsh

We purchased this car in June 2009 for $7,000 from an AutoTrader ad - we didn’t need another car at all but it looked and drove well. I had a pre-purchase inspection at my Independent Mercedes-only garage. It had been an Arizona car since 1999 and had been driven only 38,000 milesin the past 10 years; it did suffer from some non-use issues, but basically was a very strong candidate that had been well taken care of. I have documentation on this 126 from new from a retired colonel in the Air Force in Alexandria, Virginia. The car had 100,000 documented miles on the odometer miles and an $11,000 work order receipt from an MB dealership in Alexandria, Virginia, for a replacement motor installed in 1999 at 61,000 miles. The interior was superb. I spent $3,000-$4,000 post-purchase to bring it to assembly-line standards front to back, inside and out.



I’ve invested a total of about $12,000-$13,000 in it at this point. Each of my classic Mercedes are every day, drive-them-Atlantic-to-Pacific cars. They aren’t show cars, but they’re not treated as just old used cars either.

I know the 350 6-cylinder diesel gets a bad rap, and I have to say, it earned it in many respects. But this factory replacement motor is solid as a rock and uses only a quarter-inch on the dipstick between Mobil Delvac oil changes every 3,500 miles. It is my “Peterbilt;” it pulls like a locomotive in any weather or wind. I’ve never had a car before with an a/c system you had to turn down after a while when it’s 100F outside, but that’s what I have in this car.

This 126, like my other classic M-Bs, doesn’t leak oil, has never been hit, and has original paint and chrome in excellent condition, with no signs of rust. Even the fender wells are clean; I just power-wash them occasionally. There’s nothing broken or weak, inside or outside, 20 years after it was originally produced.



I use this car 12 months a year, cleaning it several times per week in winter, and it goes anywhere, anytime, across the country. Given how this 126 serves me, it would be close to impossible to replace it. I like the clean Euro headlight appearance. and it has solid Euro handling on the interstates, not the sofa style of many luxury cars. I take it on 3,000-mile trips and drive it about 12,000-15,000 miles each year. While it doesn’t have the luxury appointments of the new M-B models, this car may be the most premium-built vehicle I have owned.

I keep every aspect of it maintained to operate as it did off the showroom floor and it still is my lowest cost-per-mile vehicle. Mechanical comes first and cosmetic comes very soon after. It seems to me that the 1991 126 is as late a Mercedes as you can own to keep the solid build and avoid most of the computers and gadgets. My other MBs are the 1983 300TD and 1972 280SE 4.5, both in superb condition and hold wonderful vintage charm. But this 350SD is above all the rest for solid driving and a quality ownership experience.

My advice regarding these cars: If you find one that’s just alright, pass it up. If you find a great one, jump on it. It pays to wait for the best example you can find and pay more for it. You’ll come out much better in the end and you’ll love every mile.
 

 
VALUE ESTIMATES

*Car with replacement engine.
Low value  is a safe driver but with visible flaws.
Medium value  is a car that is well-maintained or partially restored and could be in a local car show.
High value  is a car that is in top concours condition – as nice as a new car straight from the factory.
NOTE: Excellent, low-mileage examples will sell for considerably more, but may still be good buys.
 
 

TECHNICAL SPECIFICATIONS
1981-1991 – W126 U.S. Market Luxury Sedans