What gives the Mercedes diesel...
 

such reliability and long lasting service. I was just thinking about that and wondered what is different from other engines that were junk. Nowadays and during that time

sorry if this has been posted before. I didn't find anything but not the best searcher

I really dont know jack about the internal mechanics of an engine (only the basics really) but im guessing it is a product of using the best quality alloys, the perfect torquing of every bolt and the closest tolerances.

Its all summed up in:

Precision Engineering

It's why new ones are so expensive. It's not just mark up for the name MB but that they use the best parts to make the best car. When you buy one it's a 30 year investment, much like a house. It's built to last for the long haul.
Really is a case of 'You get what you pay for.' Wish I had the money to buy a new one. I'd still buy and old one, but I wish I have the MONEY for a new one.

The biggest problem with the new ones is that they are loaded with electronics, which aren't all that reliable for the long haul. Thus they always have electronics problems, the car itself is very strong and very well made. Electronics just make it ever more complex and adds ever increasing points of potential failure.

In short, they were designed to last and be repaired. Modern cars are designed to fail and be replaced.

These two different mentalities pervade the entire lifetime of the vehicle, from design conception to crusher.

Planned Obsolesence

Is that American car motto?

Even if its not planned....it just seems to go that way for them. :D

Bingo. A good sign of this was when replaceable cylinder liners were removed from the engines in the 90s.

And the addition of things like engine computers that accomplish tasks that can be done mechanically, but are easier done electronically. For example, the MW governor does some pretty complex controlling of multiple things at once, but the same could be accomplished much more simply and cheaply by a computer chip with electronic actuators and a few sensors. Mechanical things are far better suited to surviving the harsh environment of an automobile than electronic things, and much easier to diagnose and repair.

Could it be the number of main bearings on the diesel's crankshaft.........?

Nope, they all had a full set after the OM636.

Low HP to CC ratio? :D

For our engines thats very true. Forklift engines come to mind....they're iron block iron head engines a lot of the time, have a redline of like 4000rpm and produce like 55-60hp. Way less than they *could* produce.....but they can be redlined all day long moving junk around and being abused, but give 15-20 years of reliable service. Where I used to work the forklifts were on most of the day roaring around....never once did any of them have an engine problem.