My neighbor is still on his search for a diesel Benz. Unfortunately around here nobody is selling theirs. My niehgbor has been concertrating on the 1990-1993 diesels, but has had no luck in locating one for sale. Of course I keep telling him that there is a reason you don't see people giving them up. He is currently out of the country, so I have been searching the papers and online for him. I did find a 1987 300D that has the 6 cyl. engine. It has 181K miles and the asking price is $9500. Other than the trap oxidizer problem, anything to watch out for with these engines. Is this engine a DIYer, like my 617 engine? I have been able to find some W123 diesels, but he and his wife like the "newer", more modern look of the W124 chassis. Thanks in advance.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

There's really very little difference between the 86/87 diesels and the 90-93 diesels. Both are, of course, the 124 chassis, with all its attendant strengths and known weaknesses.

Most folks probably don't realize it, but the 2.5 liter 5 in the later cars and the 3.0 liter 6 in the earlier cars are essentially the same engine. MB has for decades designed engine "families" rather than individual engines. They produced this diesel in 4, 5, and 6 cylinder versions, known respectively as the OM601, OM602, and OM603. There are many shared parts between the engine in the 90-93 cars and the 86/87 cars.

Which to purchase? I think the answer is whichever version you can find in good condition with reasonable milage. There are not many of these available, so best to take what can be found. Between two equal versions, I'd pick the newer car, though it would be quite a bit more expensive.

As for relative strengths/weaknesses: The early diesels need to have the trap oxidiser removed. However, this is free, and brings them to parity with the later diesels, which use an oxidation catalyst. The earlier cars will occasionally crack a head, which is an expensive repair. The head casting was modified during the late 80s to eliminate this problem, so this is one advantage of the later cars.

Other than that, the 90-93 cars pick up the running changes in the 124 line - upgraded interior with more wood/leather, body colored bumpers, larger a/c compressor, etc. Though nice, these are not real decision makers.