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

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- - Which is a better engine: 12-v Cummins 5.9 or Merz 300 turbo? (http://www.peachparts.com/shopforum/diesel-discussion/280247-better-engine-12-v-cummins-5-9-merz-300-turbo.html)

Quote:

Originally Posted by woodrat (Post 2496886)

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.

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

Quote:

Originally Posted by FinnJohn (Post 2497121)

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.

Quote:

Originally Posted by Phil (Post 2496862)

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.

Quote:

Originally Posted by Craig (Post 2497123)

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

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.

Quote:

Originally Posted by Craig (Post 2497151)

... 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.