Faults:

This car has barely had any problems. The ones it has had don't have much to do with reliability or dependability. I've always said "a Mercedes-Benz with an OM617 diesel will run, even when it's broke down!" The OM617 diesel will fire up and get you home, no matter what.

The day I bought this car from the second owner, the odometer stopped turning. Just broke, froze as I was leaving the gas station down the street from the seller's house. So it showed something like 251,828 all the way home. And I had to drive it from Walnut Creek/San Francisco to San Diego. So to this day, the odometer is off by about 1,250 miles; I had it repaired at the Speed Shop in San Diego a few weeks later. Aside from that, I've had the following issues over the last 4-years:

Power radio antenna broke

Muffler hanger broke

Replaced front driver side power window switch*

Headlamp/High beam problems

Power steering pump failed

* This was my fault. I spilled coffee on the switch. Eventually, it was too sticky and it jammed.

All but one of these were minor and inexpensive repairs -- the door locks and headlamp issues were related to bad fuses and some old, worn out wiring. Had to replace some brackets that were easily found at the German wrecking yard in Chula Vista for $10 each. Replaced the power antenna with a Japanese aftermarket version for $118. Muffler was fixed for $400.

The only major item has been the power steering pump, which actually was already leaking a little bit when I bought it so I knew, eventually, I'd have to address it but it managed to fail before I got around to it. Still drove perfectly fine, though. Even without power steering. Ha! Ha! Ha! That has been the only expensive repair on this car, to date. Considering I paid $2,000 for it, and then it took almost four years before I'd spend another $2,000 on servicing the car, there really isn't much to say. Other than, that I believe, the W126 chassis with the OM617 5-cylinder diesel (or M103 inline-6 gasoline engine) is the best car ever made. And if we look at how long Daimler-Benz produced this chassis -- from 1979 to 1991 -- it couldn't be more clear: The W126 is the ultimate representation of the 20th Century motor vehicle and the apex of automotive engineering and design... the company's crowning achievement.

General Comments:

I have owned several of the W123 and W126 chassis' from Daimler-Benz.

The first was a 1988 300 SE that I drove cross-country. From Los Angeles to Virginia Beach and all through college. The transmission failed just before graduation and was too expensive for me at the time, so I sold it to a neighbor who then replaced the bad trans and gave it to his wife. His daughter is still driving it to this day, 20+ years later.

Then, I got a 1989 300 SEL from the original owner up in Ojai along with a 1990 420 SEL from some guy in Hollywood, off a Craigslist ad. The '89 300 SEL went to my ex- after our split. It later needed a head gasket so she sold it to a young kid who fixed it himself and it's still on the road. That car was in show condition. Literally, a perfect 10 interior and a 9.5 exterior.

I should never have sold the '90 because it was white on grey and I loved how it drove. It was like new, that car. It had one big dent near the hood just above the driver side headlamp but was otherwise a flawless example, inside and out. In fact, I spent $600 just to replace the center console burl wood around the gear shift lever, but in the end, I simply had way too many cars at that time (1985 300D, 1995 E420, 2004 LS430, '99 Toyota truck, etc.) and nowhere to park all of them. I began posting a few cars for sale online and it was one of them. Eventually, it would go to a young woman who lived nearby. She was a struggling single mother of two, desperately needed a reliable commuter car but couldn't get approved for a loan. So she gave me $800 and I financed her for the rest at a 12 add for 9 months. She paid it off on time, too... still has it.

Before, I had had a 1984 W123 300D turbo diesel that was practically a show car. Rarely driven, as I was driving a 2001 BMW 540i at the time. Navy blue with Palomino leather. 100% original and in perfect condition with totally rebuilt A/C. I bought it from a doctor in HB but when the speedometer broke, I sold it to a couple from Newport because I was too busy to deal with it and had a bunch of other headache cars already. Another foolish move on my part. It too, is still on the road and elicits raving compliments everywhere they go!

I also bought a salvage title 1985 300 D turbo diesel in black on tan, and that was the car that I learned everything on. Cost me $800 and I put another $1,200 into it, but when I was done, I understood better than ever WHY the W123/W126 chassis' and the OM617 in particular, are so revered, HOW well they truly are built, and WHAT is required to maintain them and keep them going for 1 million miles or more. The key to unlocking the power and fuel economy of a high mileage OM617 diesel is to religiously perform a valve adjustment every 15k miles, and to ensure the synchronization of the turbo, vacuum pump, and transmission -- the ALDA boost system. Once this is setup correctly, these cars are heavenly to drive, with endless reserves of power for fast acceleration and a consistent 30 mpg fuel economy.

The W126 is an S-class chassis with the power plant and drivetrain of the W123 chassis. You get a larger cabin and the comfort of an S-class with the ride, fuel economy, and indestructibility of the W123 -- predecessor to the modern E-class we know today. This car, in my opinion, is overall the best car ever made by any company anywhere, ever. Even the gasoline engine variants are as tough as nails and just as reliable as the diesel. But the OM617 diesel is a different animal that, in all likelihood, will easily outlive every gasoline engine of its era. A very special engine design, indeed. Simple. Powerful. Reliable.

Faults:

Barely anything electrical worked on the car when I acquired it. Many mismatched parts that made me think the car had been salvaged before. I had to fix everything myself.

CV boots are worn and showing cracks after 27 years of use.

Transmission vacuum maladjusted, tranny shifting hard.

Rear windows' fastening clips broke 2 months after buying the car, replaced them with new ones, which broke off after a year.

Worn seats.

Headliner ripped.

Auto locks for the doors inoperative.

MPG went down from averaging 32 down to 23 combined city and highway, suspect worn injector nozzles.

Mid console out of adjustment due to broken plastic.

General Comments:

This car is probably one of the best cars for the DIY person. Every component is very accessible and easy to replace.

On that note, it's better to know how to do, at least, basic maintenance on these cars. Auto shops were trying to charge me US $85 for an oil change, citing the very common excuse "Oh, it's a Mercedes; a very different kind of car, you need 9 quarts of oil in it" I did it myself, and found it easier to do than in any other car I have ever owned. It does take the 9 quarts of oil to fill up though.

Also, new parts for these cars are NOT cheap. Good thing is that you can get them at you local junkyard. With a little luck you can make yourself a really great car, cosmetically and mechanically speaking, on a really low budget.

Great brakes as one would expect from an S-Class Mercedes Benz.

The acceleration off the line is not great, and I thought the engine was dying when I first acquired it, however, after educating myself better on the car via Internet forums, I learned that it is normal.

However, once the turbo kicks in, feels very comfortable at highway speeds.

The suspension is very good and comfortable. Cabin maladjustment makes it a bit noisy going over road imperfections, but the ride is very comfortable.

The engine, if adjusted properly, is very economical, yet powerful (again, once the turbo kicks in).

When I first acquired I was averaging a combined city and highway MPG of 32. I'm averaging 23 now. Time to adjust that engine.

Finally, the styling is just timeless. Properly kept, and maybe with AMG wheels, nobody could guess that you're driving a 30 year old car.