Thank you all for the reports.
I found pretty good info on the good and bad for the various years on wikipedia - a pretty good source of data on all mercedes models and their engines. Really handy for years/models/engines/production numbers, etc.
So the die-hard 617 motor is the 5 cylinder going way back, came in the 81-85 300SD. Understandably these are the true tanks that will run forever if taken care of. BTW, valve adjust is one of the easiest I've ever done on my 616. You just have to have the bent 14mm wrench set which I was able to buy used on ebay for $50.
All of their diesel models went to the updated 603 motor in 85 and that's where some of the problems started. 86-87 had the oxidizer trap that got replaced or removed under warranty. That was the culprit for blowing up turbos and etc. They also have an aluminum head that can crack if the motor overheats. Apparently this was more or less dealt with and reports are that these are also solid high-mile cars.
By 90-91 they had fixed the prior issues and decided to bump the displacement and resultant power by adding another cylinder using the same bottom end as the 5 cylinder which didn't work out all that well. These were the 350SD and SDL models, only built for two years for a total of about 2000 +/- cars. Although MBZ never formally recalled them, they did replace a LOT of those motors under warranty. There must of have been an upgrade to the rods as the new motors were fine. I understand they all have problems with enough miles, city driving miles being the worst for them, but if you can verify a replacement motor in them they are really nice cars.
My driving is pretty reasonable annually. Between 2 drivers and four cars we put on about 15K miles. My office is 4 miles from home, and usually go home for lunch. So I put about 20 miles a day on, and drive the other cars or the motorhome on the weekend and for any trips. My truck has gotten about 4K miles year for the last 3 years, but we sold the boat so now it just sits. Wifey's bimmer convertible gets about 3K a year, but she's been out of work and mostly home. The new scion xb runabout (toad for the motorhome) gets about 8K a year and our new studen driver has been relagated to that one for now.
So a SD for me would see maybe four or five thousand miles a year max. I would like to have one because they are luxury, beautiful, and still econonical with their diesel engine. I would park the 240 in the garage and drive the 300. I am able to perform all maintenance and repairs regardless of what they are, even down to trans or engine r&r. I've done body work and paint as a hobby for almost 40 years, and fully capable of complete restoration work. I have a doctorate in 'fix-it'.
Here's an interesting ad listing. I think the car is a few thousand over-priced, but a nice example nonetheless. I've written them to ask what they have on the engine status. If it has a mercedes replacement motor in it I would love to own it. If not I would pass. I'll post the link here, it will work as long as the ad listing is active. It's a 91 350SD with 64K miles, asking $12,995:
http://www.autotrader.com/fyc/vdp.jsp?ct=u&car_id=281617475&dealer_id=57334618&car_year=1991&rdm=1278086790742&lastStartYear=1981&model=&num_records=25&systime=&make2=&highlightFirstMakeModel=&start_year=1990&keywordsfyc=&keywordsrep=&engine=&certified=&body_code=0&fuel=Diesel&awsp=false&search_type=both&distance=0&marketZipError=false&search_lang=en&sownerid=74651&showZipError=y&make=MB&keywords_display=&color=&page_location=findacar%3A%3Aispsearchform&min_price=&drive=&default_sort=priceDESC&seller_type=b&max_mileage=&style_flag=1&sort_type=priceDESC&address=92870&advanced=y&end_year=1992&doors=&transmission=&max_price=&cardist=981&standard=false&rdpage=thumb
I'll save the main two pics to my photobucket acount so it will stay here:
