Noooo! Not the 603. Go with the 602. Way more room under the hood. About 8 mpg more 37 i get aboyt in mixed driving I love my 1993 2.5 t. I run it on wvo single tank and blend. Right now it has 50% diesel 50 % veg. That is what the car likes the best. Hopefully it can take The wvo abuse a 617 can. It has 265,000 on it now and doesn't smoke a bit.

The 603 is fine but the mpg sucks. 28 mpg in my wagon on highway. Not a big enough improvement in mpg to warrant liking it over the 617. The 602 though with 38 mpg, thats awesome. All the horror stories I read on here about the aluminum heads cracking and what not had me scared but now almost a year with only 60xs I'm hooked. Although I love the solid feel of w123 and how it drives like it's one piece where with the w124 when they need some bushings or something you can tell they are a bunch of pieces bolted together.

Youll like the 60x. It Can last forever too. Many refinements -- hydraulic valves, better injectors, tranny, built in fuel heater, tilted injectors for better combustion. Lighter.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

I've ridden in and driven 603's and found them to have less off the line torque than a 617, which is not optimal when zooming around the city. I know the 603 is a little quieter and a little smoother, but not enough so to make it extra special when compared to a 617. If I wanted super smooth/quiet/powerful I'd just get another M103....I enjoy the one we have, but find it boring for general driving. I like the diesel sound and throb. If I were to move to an engine that was not a 617, I'd want a 606, not a 603. The N/A 606 makes more power than the turbo 603, and the turbo 606 is just awesome.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

How do you figure the 606na makes more power? I believe that the original spec with the trap-ox is about the same, ... probably a bit more without the trap-ox (not near the specs to look them up). The '87 is a faster car than the '95 and I think that the '95 is closer in performance and fuel mileage to the '90-'93 with the OM602. I'd expect that the 606na isn't more powerful, and being an na it needs to rev to make power and above sea-level it of course loses 3% of its power every 1000' ... if I'm going 606 it might as well have a turbo/aftercooler (my some-day swap for a T124)! There's not much you can do with a 606na for more power either (BTDT), the turbo engines however are always ready for upgrades.

More torque from the 617? By spec? If you've driven a 603-powered car and found it to have "less off the line torque" I assume that you mean the butt-dyno indicated less acceleration, which is likely due to the taller gearing as IIRC it has the torque. You might also have driven one of the 99th percentile cars with in-op boost enrichment or out-of-spec ALDA and a lenghtened/out-of-adjustment Bowden cable.

I'm still voting heavily for a 60x engine in a 124.

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Gone to the dark side

- Jeff

The 606 is my least favorite engine. Especially in a W124. I had to work on my friends 95 E300D NA with 170,000 the twin to my 93. Talk about expensive parts. 500.00 oem wire harness. Glow plugs 30.00 each. Plastic fuel fittings at the filter . Lucky for her, expensive glow plugs wont be a problem cause you can't even dare to change them because they break off in the head all the time. Search here for 606 glow plugs and read all about it. There is no room to work under the hood on that thing either. Its huge. It is awesome it gets 36 mpg though.

Now that's just to work on. Drivability wise, it does have a smooth power curve and more power at low end but the 2.5T definitely compares and when the turbo kicks in will out do it i bet. We'll race em sometime. The 603 Turbo is definitely way faster than the 606 NA. I bet the turbo 606 is awesome to drive. But since the OP is talking about putting a 617 in place of a 603, drivability is not his main concern and awesome, simple, cheap, low, maintenance, rock solid, lifelong dependability is.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

Still though, if low maintenance and dependability are the goal, I'd stick with an engine/trans combination that is available in the car, no custom fabricated parts usually helps keep maintenance down.

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Gone to the dark side

- Jeff

This is what I have been saying for years to do GPs on the SDL, a few allen bolts and out it comes. The No 2 I think is what gave me the most hassle when I had THREE dead ones last year and the car started and idled like a top fueler until the other cylinders generated enough heat to run.



Exactly, each of the 603s I have driven each were not receiving fuel enrichment when boost came on. Two 300D, two SDL... one SDL is mine now. PLUS three were '87s... two with semi plugged cats under the car, one plugged so bad the car could barely accelerate.

My SD is slower than my SDL from idle all the way out to 80mph, after that the cars are just too slow to compare and I do not wish to have traffic tickets. SD has new injectors, 2° of chain stretch, proper valve lash, etc. It simply is running the best that it can. Both have the 2.88:1 gears too.



The swap sounds interesting, but I would just sell all the dead crap off and buy the best car you can afford with the profits.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

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