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

FinnJohn · #1 06-30-2010, 12:09 PM

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?

DrewGerhan · #2 06-30-2010, 12:29 PM

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

Rick Miley · #3 06-30-2010, 12:31 PM

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

Phil · #4 06-30-2010, 12:38 PM

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.

PaJon · #5 06-30-2010, 09:31 PM

Quote:

Originally Posted by Phil

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.

+1

#6 06-30-2010, 12:43 PM

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

#7 06-30-2010, 12:47 PM

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.

woodrat · #8 06-30-2010, 01:26 PM

Quote:

Originally Posted by LarryBible

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.

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

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.

#9 06-30-2010, 02:48 PM

Quote:

Originally Posted by woodrat

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

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.

#10 06-30-2010, 12:55 PM

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.

Ken300D · #11 06-30-2010, 01:09 PM

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

jkubica · #12 06-30-2010, 01:29 PM

Quote:

Originally Posted by FinnJohn

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?

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

woodrat · #13 06-30-2010, 01:33 PM

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.

tbomachines · #14 06-30-2010, 01:43 PM

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!

Junkman · #15 06-30-2010, 01:45 PM

Quote:

Originally Posted by FinnJohn

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,

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.