I spent half of my working life time in and around the dynos and test stands at one of the big name outfits that worked with every big ticket company out there. I've seen the bottom ends ejected out of every brand name engine at one time or another (usually many times) except for one. The only engine we never blew up was a Cummins deisel. That includes everybody fron CAT to Mercedes. But on the otherhand we did actually wear out a couple Cummins deisels in the 25K test, but couldn't blow them up.
While the power packs were on the dyno, they mimiced pulling a 10,000lb load atop a trailer that weighed several thousand pounds. The dyno brakes were programed to imitate stop and go driving and speeds as high as 80mph. Grades from simply ridiculous to the samething going down hill. The standard test lasts 25,000 hours, and few survive 5,000 hours. The engines run 24/7, and the only time they are shut down is to change oil and filters. While all this is going on, they are doing similar tests out on the highway with a tri axle trailer that has a 10K cube of concrete on it in all kinds of weather. The milage equivlant to 25K hours is roughly 750,000 miles. It's a hard test!
G.M. went thru a lot teething issues the first couple years they built the Duramax. Catastropic failures were the norm, and I mean seriously catastropic failures where you went in there and just picked up all the pieces laying around. (usually lots of pieces). The third generation finally started to show serious promise. And the fourth generation ended up being pretty good, but with some other issues (gas milage and emmisions). At the sametime we started developing a drivetrane for the Ford Superduty truck. We started with a five speed automatic, but Ford came in midway as said they wanted a six speed automatic. So we did a simple redesign to develope the six speed. It seemed like every three weeks Ford was changing their specs, and they literally acted like a bunch of 12 year olds throwing a tantrum. They eventually decided to go their own route for their new deisels (we'd already trashed about a two dozen of them). While all this was going on Dodge and the Cummins just rolled along as if it'd always been that way. But somebody at Powertrane decided to not sell to Dodge (what an idiot!). That would have been a serious cash flow at a time when we needed it. We redesigned the bell housing on the six speed to fit the Duramax. That part is history! But actually there's even more. At the sametime Mitsubishi sent us two or three one ton pick up trucks that would never be sold in the USA. Can't remember whether they used a CAT or a Cummins engine, but they spec'd the LCT 2000 series gear box. The bed was wider and over a foot longer than any U.S. one ton truck! The engine was a seven litre deisel, and everything was way over built. Several construction outfits tried to buy them when they saw them on the road. The crazy thing about all this is that Mercedes was buy all the LCT2000/Cummins power packs we could produce, but they never saw a minutes in a pick up truck!! Then somebody got the grand idea of moving the LCT 1000 to Baltamore, that ended up being an in house joke. That place does not build a gear box with near the quality that the original was. Look at the serial number plate for the numbers 933 on it. If it dosn't have 933 on it, avoid it.
The best G.M. trucks sold are the 2004 thru late 2005. Mileage means little with the deisel. Yet the late ones have better frames. With Fords, you want one with the old Navstar engine (7.3 era), but with a manual transmission. There was a very short run of them made with the Allison AT542 gear box, but these are not very common. You find one of these, and you got a winner. The 542 gear box will stick out by its huge oil pan alone, and is actually stronger than the LCT 1000. With a Dodge, I'd look for a manual transmission. Have heard a lot of good things about their newer auto's.
Gas mileage wise the Cummins is best. The Fords are the worst. The Duramax will often get around 20mpg on the highway, and some folks claim 22mpg. We never saw that! Pulling a load will drop the mileage about 15% to 20%. Interestingly the Dodge shows little difference (maybe two mpg at the worst). Now if you have one of the very early Duramax engines, it is not uncommon to see the fuel mileage cut by almost 50%. (that would be prior to 2003). Have heard that the Duramax is undergoing another redesign to help clean it up, and yet keep it's torque specs. Cummins has an NG version of their engine, and it's been a rumored option in the Dodge.
The big boys have been developing a half ton deisel option, and they are waiting for the economy to move. Dodge will use another Cummins. G.M. will build their own like Ford. The Dodge has showed 24 to 25mpg in on the road tests and at the Cummins test track. G.M. is showing 24mpg. Have not heard what Ford is getting, but should be similar. The the trucks are basically a 7000 pound 3/4 ton. I know that Dodge and G.M. are done with theirs right now
gary
