the best diesel engine of the 70s-80s
 

hello guys, I'm new on this forum, but I love old mercs, especially diesel ones, which are known to be very reliable; the only problem is that I can't find out which, between the om615, 616 and 617 (non turbo), will last longer without major problems; so, if I had to pick between the 200/220d, the 240d and the 300d, which one should I choose? thanks in advance

"the best diesel engine of the 70s-80s?"
Cat 3208

Detroit Diesel 6-71

More important is knowing what you're getting into. They run great until they don't, and it gets expensive. The vacuum pump grenades and takes out the whole engine, the belt cuts through the oil cooler line and bricks the engine, the transmission gives up at 200,000 on the dot, a rod starts knocking all of a sudden for no reason at all...

Lots of scenarios you can read about on this forum. If you don't have a lot of money, make sure you love working on it, love scrounging for parts, and enjoy people in parking lots telling you, "These'll go a million miles!" (After you replace the engine and every other part a couple times over, they sure will.)

If you're going for just straight hard core durability and longevity it would be hard to beat the OM601....but at 72HP it will get you there just not quickly. They are a bit easier to work on than their OM61x relatives but also generally need less ongoing servicing. Mine had 335k+ on it when I sold it running fine, I had replaced the lifters (all 8), injector nozzles (4) and timing chain + vac pump. Could run it at 100% for hours on end and it would happily do it. Car maxxed out around 85-88mph depending on conditions :D

I'd still rather have an OM617 Turbo however, so much more power, and the sound is awesome....even if it does need more upkeep.

As bulletproof as the 61X motors are, with the routine servicing needs, my vote is for the 603.
Sure, the #14 head is a bummer when overheated, and sure, the front head bolts in the chain area back out, allowing oil burn… but… overall, the power, sewing machine smooth running, the far easier maintenance… did I mention the power?

Of course, they need the vacuum pump upgrade. They need delivery valve seals every 100K… a #22 head upgrade is a dream improvement (I have one) the serpentine belt tensioning system is kooky… and the alternator really needs more output, but then you have to change to a clutched pulley on it… the stock aluminum fan is too weak, and the 606fan needs CAREFUL attention to prevent flexing into the radiator….
Why do I like it so much again?

I'd vote for the 617 na. The next series I don't have as much experience with. This era is potentially a very simple engine to work on.

There is a wide difference in the OM61x range, a 4 cylinder N/a vs 5cyl turbo are miles apart in terms of daily driving. It all depends on what you are looking for the car to do and where you drive and how much maintenance you want to do.

Live in the flatlands of Florida and take the car out to buy your weekly lottery ticket at the local convenience mart, a 240d would last you a lifetime. Daily commute in the major metropolis beltline...a 617 turbo would be a better option. If you drive a lot, you will need a lot of valve adjustments on the 61x engines. The OM60x engines dont require that adjustment process. All have their pros and cons, but start first with defining your specific needs/wants and find the option that best fulfills those later.

Longevity wise the w124 250 D (5 speed manual) with the OM602.912 (a NA 5cylinder diesel at 35mpg more efficient successor to the 25mpg OM617) was the standard for taxis in Germany known for +500K miles.

You don't mention your location. These cars were not sold in the US so if that's where you're at you'll have to get lucky or import one from Europe.

😂
Good guess but false. The correct answer is the Cummins B-series.

That response implies that there was a test of some sort involved, in which answers can only be either true or false.
The question, as framed by the OP, seems to solicit opinions. Is your response the result of a guess or of informed opinion? If the latter, please have the courtesy to credit all other responses as also resulting from informed opinion.

Nah, both you and Frank are wrong. For durability nobody could touch that era of Perkins diesels.

The IHC DT466 was a fantastic engine but weighed 1400+ lbs. which ruled out its use for any light duty applications.

The 3208's had electrolysis issues plus it weighed 1600+ lbs. Great engine for boats or construction equipment due to its economical fuel use.

The early Cummins 4Bt's had problems with their camshafts plus the "Killer dowel pin". I still have four or five replacement dowel pins in my tool box from my wrenching days. The camshaft issues were resolved in the later 80's with a revised turbocharger mounting.

I was being facetious. I love’em all, just can’t afford to have more than three at a time. I recently read an article by the same title as this post. The writer equated the question with asking a mother which of her children she favors most. However, I do think any and all entertaining the question can agree on one thing: It’s got to be a Diesel.

Apologies to the OP for high jacking your thread
 

I think(aka MHO) all of Mercedes diesels are great but I’m only familiar with working on the 615, 616, and 647. Excepting the latter(opinion) the early diesels are fun for the beginner enthusiast and professional alike. What makes them great to me:
They’re relatively simple, easy to maintain, fun to work on, parts availability, enthusiast support like this forum, and the fact that despite horrendous abuse/neglect there are so many of them still in service. That makes them great to me.
Can they compete with a modern diesel? In some aspects the answer must be ‘Absolutely’! But to be fair a comparison between an OM617 and a Cat 3208, 71 series jimmy, B-series, et al… that’s just apples and oranges. Diesel technology has far surpassed performance capabilities but operating and maintenance costs…? Yeah those have far surpassed the older OMs on at least the same gradient with performance. I think a great diesel engine is only as good as it’s application. There’s a lot more 616 and 617 transplants than non OEM engines transplanted into Mercedes. I can’t recall hearing of one but i’m sure there out there. The 616 is still produced on license to a company in India for new production cars. Considering the number of choices available I think that speaks volumes. They’re still a cost efficient power plant if you don’t need to pull a house off it’s foundation or break a record a Nuremberg. I expect 616 amd 617 will be around for decades to come. I hate to use the metaphor but these engines(in my experience) are like the unconditional love a dog shows his abusive owner. They live better longer if you treat them like you ought to. Abuse them regular and eventually that dog won’t hunt.

My favorite is the 606 in the 98/99 E300. Got one in shop now that just turned over 375k miles and still on original head gasket. The injection pump was recently replaced with a new old stock.

Nothing to do with engine but it is also on the original transmission.