Quote:
Originally Posted by DieselPaul
Its critical to note the 603 REPLACED the 617. Mercedes isn't stupid, they wouldn't have spent millions in development, R&D, testing, etc to build a motor less modern than the last.
Do you know what is smoother than a 603? A 606.
Do you know what is smoother than a 606? an E320CDI.
Do you know what is smoother than a CDI? a new V6 Bluetec Car.
Its progress. The motors get more complicated which is probably where they get a bad rap as certain things are harder to do in your garage, but the fact of the mater is the 603 is a more technologically advanced motor than the 617.
I did all the filters on a 617, ran injector cleaner in it, verified the timing, and we had the dealer adjust the valves, the 617 can be very smooth.
And with leaking delivery valves a 60X can be hilariously rough.
Either motor, if its a healthy motor and you are up to date on maintenance it'll be a nice car. But that's true of most cars.
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This is a good post and very accurate. I've owned many 617s and I love them, but a good OM603 is a much more refined engine with more power and torque. I had a 1987 SDL for a time with an excellent engine and transmission, (it also had a later #22 head), it was very sweet car that I miss.
I've also owned OM617 powered cars in great condition, (both w123 and w126), they are fantastic but technology marches on and the jump from the 617 to the 603 was one of the biggest jumps forward in diesel refinement for MB. The problem, as stated before, is that no engine with an aluminum head takes overheating very well. The OM617 is a cruder power plant and has a cast iron head that is very tough. I've seen plenty of people kill an OM617 as well, usually from lack of lubrication from oil leaks and not checking oil, (or running SVO and ruining engine), but they will survive the occasional overheating that the later engines will not.
Any of these engines in good condition that has been maintained and not overheated will be great. The problem is that as the cars get older, they fall into the hands of less affluent owners who either can't afford to service them properly or don't care about the car anymore. An OM617 will take a hell of a lot more abuse and deferred maintenance than an OM603. If you can find a good OM603 car, they're awesome and can run forever
with proper maintenance. 