Which is a better engine: 12-v Cummins 5.9 or Merz 300 turbo?
 

Hi guys, my stepdad and I got into a little debate over this last weekend. FWIW, I was arguing for the Cummins -- my position was that it's twice as big yet gets almost the same fuel economy lugging a three-quarter-ton pickup around as the Merc gets pulling a sedan body, and never wears out. He shot back that it's just because the Merc body is built to the same standards as the engine, that it still looks good at half a million miles but a Dodge pickup is falling apart around the engine by that point, which makes the engine look more heroic in comparison. He then goes on to tell me there are 617 engines with a million miles on them and he doesn't know of any 5.9 Cummins that's made it that far without a rebuild.

Hey, he might be right. Whadda you guys think?

Considering vehicle designs, Mercedes wins.
Considering engines, I'd take a Cummins over a Benz, but it'd be close.

I'm wondering what you consider "almost the same" as the 26 mpg I get in my euro.

My only complaint with the newer diesels is they all now have electronics controlling them. The old MB's don't have the electronics to mess with and to me that makes it a lot easier to work on. Once they add all the electronics it might as well be as gasser.

The Cummins might be interesting, but it's surrounded by a truck.

I've driven both and I would call it six of one and a half dozen of the other.

Don't say that there have not been 5.9 Cummins go a million miles until you have some firm data to back that up. I've never done any research on it, but I would be SHOCKED if there aren't a number of them that have made a million miles. I sure shudder to think about how bad the cab rattled at that point though. The worst part about driving a Dodge pick up is that every time you slam the door, your first inclination is to roll down the window and look out to see what fell off.

http://forums.motortrend.com/70/88046/the-general-forum/check-this-out-million-mile-dodge-3500/index.html

http://answers.yahoo.com/question/index?qid=20070724124252AADxNJ3

I just googled "Dodge Cummins Million Miles" and this is a couple of what I got.

I know the Mercedes engine has replaceable cylinder liners. If you really want to, you can restore the engine to something resembling a "no-wear" condition.

Does the Cummins 5.9 have replaceable cylinder liners?

Ken300D

Assuming that it wasn't the whole door that fell off... :D

I love my 92 Dodge/Cummins truck, but it's more about the drivetrain than the truck itself. It's got almost 270K on it and the engine runs like it's new, but the body is fast disintegrating. Awful early 90s paint job peeling and flaking away everywhere, cowl cracks that leak water into the cab whenever it rains (there actually used to be a cowl patch kit available from the dealer because this was such a common problem, even on low mileage trucks!), doors that are literally about to fall off their hinges, seat beaten down into nothing, window tracks that are repeatedly falling off the windows, and all kinds of little fleeting electrical glitches that are nearly impossible to track down.

The only thing that has ever gone wrong with my engine in the nearly 100k that I've owned it is that the in-block oil cooler spring a leak. It was a nasty, awful mess to clean up, but the part was not that expensive, and the repair was easy. While I had it apart, I pulled the oil pump and measured it for wear and it measured as having literally no wear at all, at over 250k miles. I've seen pictures of the cylinders of an early 12 valve engine at 350k that you could still see the cross hatch pattern in. I've got no doubt that one of these engines, properly cared for, could last a million miles.

That being said, I'm pretty excited to finally have a good Mercedes diesel, too. I used to have VW diesels, but the last one I had dropped a valve only 2000 miles after putting on a "new" head (I suspect cheap, non-VW valves were used), and I decided I wanted an all cast iron engine instead.

The Dodge Cummings is a great engine in a crappy truck. I know from experience that the engine is good for 750,000 miles plus with just normal maintainence - oil, filters etc.

The Dodge undercarrage & drive train give a lot of trouble long before they should.

Mercedes 617 is a good engine but most don't make it over 400,000 miles without a rebuild. The Mercedes body is very well made but the undercarrage and drive train require considerable rebuilding to make the 400,000 mile mark.

Just my opinion,
Joseph

I did have to replace the Getrag 5 speed in my truck at just over 200k miles. At that time, parts were expensive for that tranny, and no one wanted to rebuild it, so I upgraded it to a New Venture instead, and have been really happy with that choice. I have had some minor front end issues, and I'm due for kingpins now, too, but nothing major. All the truly worn out stuff is in the body department.

You'd be hard pressed to find an OM617 that reached a million miles. Likewise you'd also be hard pressed to find a cummins diesel truck that legitimately gets over 30mpg (driving my SD on the highway yielded over 30 regularly). There are a lot of myths out there...call Jamie and Adam!

I call bull. You don't get the same mileage out of the Cummins as the 617. Besides, they are for different applications. Dodge put a 50,000 mi truck around a 500,000 mi engine. For proof, look at all of the cracked dash, steering, suspension, KDP & transmission threads on the Cummins forums. It takes $2000 in aftermarket parts to make the truck NEARLY what it should have been from the factory. Switch to the 24V Cummins & add $1,000 VP failures with requisite tow bills to the list. Anytime I think there is a problem with the Dodge, there is a problem & I get out the checkbook.

SD problems have been limited to climate control & filters. SD has 240,000 mi, Ram has 150,000. Absolutely no way that the Dodge is as reliable. On the other hand, SD won't tow the boat. It is getting hard to find a 12V in decent shape & only the 98s had back doors.

Of course you don't. That's why the word "almost" is in there, to account for the difference between my old 23-mpg Dodge truck and my stepdad's 25-mpg 300SD.

Okay Guys! Let's stop comparing oranges to apples here!

The Cummins under discussion is in a truck that weighs more than half again as much as a 123 MB. This truck also has probably AT LEAST half again as much frontal area with a MUCH worse aerodynamic coefficient.

Fuel mileage is determined MUCH more by weight and aerodynamics than it is by engine size.

When I bought my '91 one ton, flat bed dually, 5 speed Dodge Cummins, I came out of a one ton dually, flatbed Ford 460 Four Speed. Pulling 15,000 pounds with the Ford I got LESS THAN 5MPG. Pulling the SAME 15,000 pounds with the Dodge took me to 14MPG. I thought my first fuel bill was a mistake.

Now, go figure ton/miles per gallon of a 3,500 pound 123 at say 30MPG and then go figure ton/miles per gallon of a 20,000 pound gross weight Dodge and gooseneck trailer at 14MPG and see which one is more impressive.

It is interesting to discuss the venerable Cummins and the venerable MB 616/617 in the same thread, but DON'T get carried away with the comparison of oranges and apples.

ROTFLMAO!

Your statement about your Dodge leaking water through the body seams literally made me laugh out loud!

I got out of the Army in late Summer 1971 and got a Service Writer job in a Dodge Trucks factory shop in Dallas, Texas. Part of the deal was use of a company pickup. The new 72's that were the same cab from that year until about 93 or so hadn't hit the showrooms yet, but since we were factory owned a transport of them rolled in my second day and I was told to go pick one out. There was a beautiful blue Limited Edition D100 with more accessories than I had ever seen on a truck.

I was excited to have this fancy truck that wasn't to be on the streets for another six weeks or so. EVERYONE had to ask me about it. It very easily could have been one of the first day's production, or given the situation, maybe even not much more than a prototype that they sent down the line to work things out.

Anyway, it was fine until the Fall rains came and we had some real frog stranglers. When that happened water would POUR into the cab and you didn't DARE hit a big water puddle without a wet suit on.

We had no body shop, only mechanical and we sent that thing to I don't know how many body shops trying to get it sealed up. I left there at Christmas to start College in the Spring semester. When I left that thing was still a lawn sprinkler inside in a rain storm.

What made me laugh so hard when I read your post is that even in TWENTY YEARS, they couldn't fix the interior leaks.

Luckily I never had this problem with my 91 One ton.

We have 5 5.9L's in Case 621 wheel loaders, 2 are late 90's models and the other 3 are early 90's models. The later models lost head gaskets right next to thermostat around 12-15000 hrs, the others all ran to over 20,000hrs with very little trouble. The 5.9 does not have replaceable liners, but I can buy a complete rebuilt running engine for $6500.00.

I agree with Larry... It's an apple vs oranges argument. What are you doing with it?

In actuality, the 616/617 engines don't have liners either. They simply have dry sleeves. They have to be rebored or removed, replaced and then bored to fit. This is unlike over the road or industrial engines with wet sleeves that can be relatively easily replaced in frame.

The Cummins could be bored to oversize for less machine shop cost than futzing around with the dry sleeves in the 616/617 engines and if need be, the Cummins could be bored, and dry sleeves put in place, topped and bored just as you would do with a 616/617.

The sleeves in the MB's should not be confused with the sleeves in the big rigs.

A modern 5-speed stickshift turbodiesel, vs a fairly antique 4-speed automatic w/o lockup, counterflow head, ... yeah, the more modern engine with the overdrive stick should do well.

700,000 with normal maintenance? Not even common in big OTR trucks. It is possible I suppose, if most/all of its miles are well-maintained fairly lightly loaded 5th-gear highway hauls though.

Goofy question, entertaining answers. Good thing Daimler-Benz got rid of that ChryCo crap.

I used to work in the shop at a trucking company- They bought trucks from OTR/long haul companies, typically with 950k to 1.2m on them, and they all came with a stack of service documents. Oil changes every 20k or so, a clutch here and there, and aside from a couple that had top-end work done, none had had the engines opened up.
A Cummins 6BT will run 500k, but then it was designed for it. It is a smaller medium duty truck engine, Chrysler managed to shoehorn them into their trucks and the rest is history. The engines as used in the Dodge trucks are turned up quite a bit from the medium duty truck version, but still they do last quite a while. As has been stated though, the wrapping it comes in is garbage.

Not getting carried away. I drive a Cummins & SD. SD engine is MUCH more reliable than a 24V Cummins. SD body is also MUCH better constructed than either 12 or 24V Dodge body. I also believe that 23mpg stated for the Cummins as an all around mileage is overstated unless most driving is unloaded in top gear going slow enough to stay at low or no boost. But yes, it is ridiculous to compare such different vehicles. The SD is a fine vehicle but I wouldn't use it to haul a load of dirt.

On the other hand, Dodge should be allowed to go out of business for the poor quality of the trucks. There is no excuse for the cracked dashes, weak suspension, VPs especially given that those failures appear frequently in one model.

Cool! So I guess the consensus is, the Cummins 12-valve is more efficient, more durable and has a longer TBO, but it's not a better engine because the trucks it usually comes in suck and anyway, it's apples to oranges because it's a different engine. Not sure what all that means, but I think the moral of the story is, I win the argument with Pops! Thanks fellas. :D

I think the short answer is: It's a domestic truck, so who cares? ;)

I have Both but the Cummins is so much more fun to drive:D:D Especially when you have 383 hp and 916 foot pounds of torque available and 6 gears to row and consistent 20 mpg! My 190D is not turbo but is awaiting the 5 speed parts sitting in the garage, and still gets 35 mpg with an Auto. Can't wait to put the 5spd but just got laid off.

+1

Wow, open mind much?

I'm guessing if you had the opportunity to listen to the sound of a Cummins 5.9 turbo spooling up as you tip into the throttle at the base of a mountain and watch the boost climb to about 25-28 PSI as the EGT settles in around 1,000F you'd be a bit more passionate about a 'domestic truck'. This is a Diesel discussion forum right?

But my all means limit yourself to the dull roar of your OM 61X engines, you don't have a clue what you are missing.

... then I'll pick up a case of bud and head over to the local monster truck show while listening to some country music.

I'll pass.

It makes my whole being shudder when I see people like that.

I have a 2004 Cummins and nothing sounds like it, but still love the Mercedes diesel.

Neither,
The 603 will smoke both of them in stock form. Crank it up and it'll smoke a cranked up Cummins. I've been tempted to tamper with the boost and fuel on mine but never had the guts. I don't have a pyro and 150 HP is enough to keep me happy.

The Finns with their impressive 400 HP 603's... that would be fun!

Come on, we all know you are more comfortable with your granola, techno and protests-
Stereotypes aside, you aren't going to find an import truck that can hold with the domestics, especially a diesel one. And before you start screaming Mitsu/Fuso, Isuzu, and Hino, show me one with a bed and 1-ton registered capacity that you can insure as a private pickup.

Funny to see people holding such strongly held partisan views on a question like this. Both the 12 valve, all mechanical 5.9 Cummins and the 616/617 Benz diesels are among the best and most reliable engines ever made, as near as I can tell. They obviously have totally different applications, but if one loves a good diesel engine, then there's a lot to love about both of these.

As far as dismissing domestic trucks goes, I do think that generally, my 82 Toyota was a "better" light truck than my 92 Dodge is, but it couldn't do nearly the amount of work that the Dodge does, even in it's falling apart condition, body-wise. I routinely tow loads up to 10,000 pounds, and the Cummins/Dodge does this with ease, while getting 15-18mpg. Hard to find much fault with that, even if it does leak like a sieve when it rains...

Yep. Apples and oranges. but if you have work to do....a trailer to haul, A dodge with cummins is hard to beat.

My 03 cummins with stick reminds me of a much larger more powerful 240d. It makes me smile when I think about it.

And its fuel economy is pretty close to what my 350SDL was. over 20 highway versus a couple or three at most more with the 350.

I agree about about the Dodge body but you cannot beat the strength and reliablity of the Cummins, particularly the 2nd gen 12v's.
It really is not a fair comparison.
I love all my diesels for what they have been designed and they all perform well if properly maintained and serviced.
BTW, I had at least 400# of fruit and nuts [for fruitcake baking] in the trunk of my 240d and other than being a little nose-high it accelerated ;) and handled as if empty with 30 mpg.
Of course, the Cummins can do the same with a ton in the bed except with less fuel mileage.
Again, it is apples and oranges

I'm splitting hairs here, but Chrysler is not the one that shoe horned the 6BT into a Dodge pickup. They hired Jack Roush to do it. He did all the engineering on it. He said that they had to do lots of things for sound deadening including a stiffener in the oil pan. I guess before the stiffener, the oil pan flexed and acted like a speaker.

So you might say that Chrysler did it because they paid Jack Roush's engineering bill. Sort of like when someone says they built a house, they really mean that they wrote a check to someone to build the house for them.

Yep, when it comes to sound, the 6BT is an all star major leaguer while our precious 123's are Pony Leaguers. Nothing like listening to the turbo spool up in one of those things. I had a sliding back window in my one ton, and I kept it cracked open most all the time, just so I could enjoy the music.

Nothing beats elitism. Ever consider running for congress?

EXACTLY RIGHT!!!!

When it comes to diesel trucks of all sizes US is KING! No one else in the world matches the US big rigs or diesel trucks of ANY size.

That said, it's not a good thing. The REASON that the US has BY FAR the greatest trucks is because the US has BY FAR the WORST rail system.

What about Toyota/Hino?
 

Very interesting thread, even though the comparison is indeed a bit meaningless as many have stated.

To add pears to the apple and oranges debate, what about the venerable 3B 4 cyl 3.4L non-turbo diesel engine in early 80's Toyota Land Cruisers (made by Hino, sleeved, also used in their forklifts and delivery trucks)? In this case, we're talking about something in between a MB diesel car and a 3/4-1 ton pickup, and somewhat equivalent to the 300GD G-wagen. Great quality Toyota truck (though those 60 series were rust-prone as hell up here in Canada, where they were fitted with diesels, much to the chagrin of folks south of the border who got the gas models), with very rugged, all mechanical commercial-grade diesel engine.

I own a descendant, an 80 series Land-Cruiser from Europe fitted with reportedly equally reliable and long-lived engine, a 6 cyl 1HZ 4L diesel. My "problem" is I am planning some long road trips up North and down South, since Freedom-55 is just around the corner, and would see myself better served in a truck/camper combo than a Land-Cruiser towing a small camper trailer. So I've been leaning on the Dodge Cummins (since diesel is the way to go for me, and I'm not as sure about Ford/GM diesel trucks).

This thread has further underlined the great engine / crappy truck issues, hence my dilemma. Occasionally nice southern 91-93 Dodges show up locally, without rust, but I gather from reading this thread that this is only one part of the equation (ie. cab leaks, undercarriage issues). One of my reasons for considering a Dodge is it could get fixed anywhere in N-A if/when ;) I had a problem with it - not so easy for a European Land-Cruiser.

I remember a story that the early 90s dodge 5.9 trucks had a frame bending issue due to heavy capacity towing ,alot of motor vs not enough truck.They fixed it with a kit to reinforce the frame underneath the cab.Heresay or fact ,not sure,its a story I heard.

That's the first I've heard that story. I talked with one of the persons I know to have worked on the early project. Said he knew of Jack Rousch from living in OH from racing. But, didn't know of any conection of him to the 5.9 being in the Dodge truck.
Now, I think people are comparing einges from different eras. Still, the late 80's VW Rabbit still got better gasmilage than a lot of these new Hybrid cars.
Tom

Dodge trucks aren't actually all that bad. The engine makes them look flimsy in comparison and that leaky cab thing can be a problem (or was on mine -- the raingutters go all the way around the front of the cab, and if I parked on a hill rain would run over the top left and through the front door seal) but like with any other old beater built by anyone but Mercedes, you just have to replace stuff when it breaks. Before 1994, Fords are better, especially from a passenger-comfort perspective -- my old '92 was built just like a '72, with bouncy plastic bench seat and lurchy ride. But the Cornbinder diesel, while a great motor, is a pig at the pumps and not as durable or torquey as the Cummins; Chevs are better too, but then you have to get one of those Detroit Diesel 4-strokers (if it's an early pre-Duramax one) -- good motors, really, but mediocre compared to the other two.

If you do get a Dodge, make sure it has either a 727 (3-speed auto, no OD) or a stickshift.

Anyway, that's my rant for the day.:) Back on topic: I would submit that durability and efficient use of fuel are not apples-to-oranges issues. You can meaningfully compare engines on that basis. Although you guys are right, nobody is going to replace his 300SD with an old Dodge pickup for daily driving use -- well, almost nobody.:rolleyes:

It is possible, I have a Isuzu NPR with the 4L diesel. The hard part was getting it insured, but my auto ins. co. was very good about it.

Don't forget the Duramax is an Isuzu product. I know nothing about it but I've heard good things.

Thanks, but I don't need an additional incentive to make fun of the truck driving redneck clowns that still exist in this part of the world. I'm not talking about people who use these ugly things for work, I'm talking about kids with chipped $40k trucks with chrome stacks and truck nutz. These morons make all diesel drivers look like idiots, it's about time to enforce some noise and emissions laws before we turn into TX.

I wasn't clear, I have no use for any kind of truck. I don't need or want one.

So now you're assaulting Texas? This may come as a surprise to you, but I've lived all of my 61 years of life, except most of my Army time, in Texas and I don't have a huge, chipped 4X4.

You're not explaining away your elitism, you're expanding it!

Sorry, but I spend too much time in the DFW area with the "cowboys" who drive these things (big hat, no cows?). I know lots of folks who work/live in TX and the vast majority are perfectly normal. Besides, if you ever go skiing in CO you will find that making fun of TX is quite a sport.

I don't need to explain anything, I take "elitist" as a complement.

Unimog.

Oops, you mean only one ton?