Could someone explain to me what the major performance/reliability differences between the 603.961 engine on an 87 300 SDL vs. the 603.97 engine on a 91 350 SDL?

What should I inspect/look for in doing due diligence on either of these engines?

Thank you.

hensmark
You need to just read the following thread, then use the SEARCH button as recommended in it:
http://www.peachparts.com/shopforum/showthread.php?threadid=99244&highlight=350sdl
DDH

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

thanks -- that helped alot.

Glad to point you in the right direction, sir.
As for due diligence, see if a seller has service records with a car. On that subject, it should be obvious that the dealer would prefer to throw out any records (if obtained with a car on a trade in, highly unlikely) because it can mislead a potential buyer into believing the car needed a lot of service for example.
I got lucky and bought a used '87 from a family member of the original owner, he had records that showed everything that had been done (at the dealer mostly). Its nice to know that such and such was fixed so you know that the possibility of those items failing anytime soon are less. It is crucial to know whether the vac pump was replaced with the updated version, the early versions of that pump could disintegrate and caused engines to fail.

Another item of almost as much importance on the '87 diesels is the trap oxidizer which was replaced by a diesel cat, something that is entirely necessary if it hasn't been done yet. Although the chances of a low mileage 300D turbo still having the trap oxidizer is remote, there was one on Ebay just a few months back! A picture clearly showed it in place alongside the engine. This does not apply to the 350SDL AFAIK.

The stretching connecting rods on the 350 make me want to avoid that model, besides the '87 diesel turbo runs better and has less electronics to go bad. OTOH if a 350 had a new engine compliments of MB with the "new" rods that are said to be a solution to the problem, I might get warm on the thought of owning one, if the price was right.

Let us know what you find out there!
DDH

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

dieseldiehard,

Thanks again for those tips. I do like the idea of the 90/91 SDL just because they are a bit newer but I'll only buy one now if I can confirm that it has had the engine replaced already or if the price is way right.

I'm heartened a bit by the availability of some 86 and 87 sdls at very reasonable prices. I've got my eye on an '86 with a shot motor and good body for $2000 and an 87 with a good motor and transmission but bad body for the same amount. I'm considering buying both and making one good one and having a whole slew of spare parts to boot.

It is also good to know from reading other threads that you could replace the 603.97 with a 603.961 and that the latter can be had in running condition for a reasonable amount.

we'll see what pans out.