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Mercedes diesel W123

Where I live–and I think nationally–there are a substantial number of guys who believe fervently in the older Mercedes diesels, especially the 1982-1985 years (with the W123 body), and the five-cylinder 617 turbo diesel engine. The problem is of course, that these cars are getting really old. The bodies seem to be wearing out before the engines.And the problem is often neither the body nor the engine, but the windows, A/C, sunroof, door locks, controls, instruments, seats, and cruise control. Are these cars only for (1) tech guys who love to work on cars themselves and (2) rich guys who can afford to take them to the shop every time something goes wrong? NOTE: under make/model, this site doesn’t allow me to select 300D, so I put 240D, all that the model selection allows.

I think you have summarized it well, the engines seem to live forever, but the other systems have many promblems, some from age, some from weak designs (A/C), so you either have to be a good mechanic or you have to know one (not a dealer). The non-turbos are slooooow, so be forwarned.

In my area, there are two kinds of W123’s. One is the kind that was owned by the quintessential older Mercedes owner who might have bought the thing new, has a four inch thick folder of receipts for every scheduled maintenance item and who fixed every little problem as they arose.

The other kind might have once been like the above, but maybe 5-10 years ago was bought by some younger person to do a fry-oil conversion. Either they did or didn’t, but they drove it around for years and neglected the maintenance and they’ve just let things like sticking locks and broken instruments slide. I’ve certainly known people who’ve done good fry-oil conversions and took care of their cars, but I’ve also known many people with more environmental zeal than mechanical aptitude who’ve bought W123’s (and other older diesel cars) to do fry oil conversions who end up just driving them around like any old disposable econobox.

I every now and again find myself looking at one of these old Benzes and I’ve found that the condition of the car is almost directly proportional to the age of the owner. Part of what used to be so great about these cars was that not only were the drivetrains invincible, but the people who typically owned them took extremely good care of them. Certainly the march of time is part of why there are more junky W123’s out there, but I think the change in owner demographics is as well.

I believe that there is a somewhat similar situation with VW diesels. 1992 and prior VW diesels had, except for the control of glow plugs, purely mechanical injection systems. After 1992 they became TDI diesels and with that became infested with electronics. The economy of running a VW diesel was mostly or even completely lost with the TDI models due to the need for expensive fuel filters every 20,000 miles, special expensive engine oil, turbochargers for every TDI model that typically do not last as long as the engine and a greater chance of a timing belt failure as the injection pump pressure was doubled for the TDI models over the older models while the overall timing belt system design was not changed until later.

Interesting observations, no doubt true.

There are exceptions of course. I have owned two immaculate 300Ds and keep another for parts. I am mechanically inclined and do all of my own work and have access to a lift. I’m in my early twenties though, so to say that the condition is directly proportinal to the age of the owner may not be accurate.

One thing I have noticed though is that the drain holes are often overlooked or forgotten on these cars until one day you have a hole forming around the jack points. I’ve seen plenty of these cars and can almost always tell how well the car was maintained just by checking the jack points for corrosion and rot.