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Discussion Starter #1
I have been looking at 3500s and noticed that 5.9s from 2005 were going for the same price as 6.7s from 2006/7. I have read in the diesel section about issues with the PAF in the 6.7 but nothing else really seemed like a problem area.

I was wondering why the 5.9 would command the same price? Is the 6.7 trouble prone?

The truck would be used to pull campers or a 3 car travel trailer

Thanks for any input guys

David
 

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From what I've seen and heard, the 6.7 had some troubles in their early days because they were designed to work hard and people just weren't putting them through their paces. Not real sure on that though. But the 24 valve 5.9 is a freakin legend. Those things are damned near bulletproof. That's why they're so expensive. My uncle, his brother (no relation), my grandpa, my dad's friend, and my dad all have the 5.9's in their trucks. Most of which are well over 100,000 miles and still getting around 25 mpg average. The 5.9's are definitely worth the money.
 

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I had a 2006 with the 5.9 in a 3500 SRW Mega cab with the 6 speed manual that I used to tow a 32' RV. That truck would straight PULL. Example, Leaving the fuel island at a truck stop. I put the truck in second gear and eased out the clutch and didn't touch the skinny pedal. Did the same thing all the way to 4th gear and walked out of the parking lot. Even going through the mountains from Kings Bay GA to Bristol TN, I passed Fords, Chevy's and every gas truck with a trailer. Trailer was loaded up for the race and had three adults and a big dog in the truck.

I wanted the 5.9 over the 6.7 for the simple fact the 6.7 was new at the time and the 5.9 was time tested. There are alot more emissions crap on the 6.7 as well. My vote and experiance is for the 5.9 all the way. Bear in mind I have never towed with the 6.7 but I'd still vote for the 5.9 because I have seen it work.
 

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They are both great motors. The only issue (repeated) I have seen with the 6.7 is WETSTACKING. If you have a large diesel and you never tow/haul, or dont tow/haul enough of the time, you will wetstack it. Wetstacking is basically a laymens term for blow-by. Its very bad for your engine.

With diesel's, the bigger the engine, the harder you have to work them to keep them running correctly. Diesel's HATE idling, and large diesel's HATE not hauling anything. they get sludgy and carbon deposits everywhere. Part of doing maintenance on a diesel should be pulling with it once/twice a year to blow all the shit out.
 

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Well, I can tell you that if you want to do any mods on your engine the 5.9L is the way to go. The tuners that are available for the engine is just amazing. My issue with the 6.7L is that you can`t really do any mods to the engine. The tuners are just not up to par with that of 5.9L tuners.
 

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I drive a 3/4 ton work truck with a utility bed that weights in right under 9k on the scales loaded, and it weighs that ALL the time. Would that be considered hauling a good weighted load? Because the gas burner truck that it is (bowtie, cough, cough) gets a lowsy 9mpgs in town and 13 on the hwy, and for the record I didnt buy it!!! I think I really need a cummins!
 

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I think that would be fine. Not extreamly heavy but will work the truck like ArmyofOne said. It's a fair load and will pull like a dream with the 5.9 and I assume the same with the 6.7.
 

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I drive a 3/4 ton work truck with a utility bed that weights in right under 9k on the scales loaded, and it weighs that ALL the time. Would that be considered hauling a good weighted load? Because the gas burner truck that it is (bowtie, cough, cough) gets a lowsy 9mpgs in town and 13 on the hwy, and for the record I didnt buy it!!! I think I really need a cummins!
thats just about perfect, but make sure to tow something REALLY heavy 3-4x a year (like close to the max). I know it sounds rediculous, but diesel's have to be worked to stay efficient and healthy.
 

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Just kind of skimmed through but heres my $.02, not that it matters lol
6.7's were introduced in the 2007.5 model year. 5.9's were still available in 06 and 07 and are like gold.
That being said they are both basically the same motor (ISB series) the 6.7 is just a larger displacement and emmision regulated features such as the DPF.
The biggest problem seen with 6.7s is with the DPF regeneration to clean out the particulate filters. THe trucks can clean the filters through active regen. or passive regen. Active regen just uses high exhaust temperatures (I.E. beat on the truck) to burn particulate out, Passive regen. uses raw fuel (Ford,Chevy use a UREA system which you pour a seperate fluid in that is used as the catalyst) in the filter to raise the temperatures and burn out particulate.
The problem occurs when the truck decides not to Passively regenerate the filter. The filter then clogs and throws the truck into limp mode.
That being said my girlfriend has an 05 5.9(144k miles) and her dad has a 09 6.7 (69k miles). The 05 was his before. When he got the 09 he hated it. The power sucked compared to the 5.9. The fuel mileage sucked compared to the 5.9. He was looking for an 06 3500 when the DPF threw the truck into limp mode. We some how managed to convince him to try a DPF delete.
He absolutly loves the truck now! The power and fuel efficiency difference is unbelievable! If I was given the choose of the two trucks I would definitly pick the 6.7 with a DPF.
The comment about tuners- I honestly believe out of any of the tuners, H&S Performance tuners are the best on the market for Cummins and they only make them for 6.7s (I wish they would come out with one for 5.9) You can do any mod to a 6.7 as you could a 5.9 (Assuming you do a dpf delete(which requires a tuner) as your first mod)
 

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Discussion Starter #13
Thanks!

I appreciate the input guys. I found an 07, 6.7. With 40kmiles. Dually, reg cab, manual transmission. Perfect for the towing we will be doing. Going to pick her up tuesday if all goes well.
I'll post up some pics if all goes well

David
 

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Discussion Starter #15
I drove down to Arkansas to pick up the truck, and found a couple of surprises. The body had a few dings and dents, but it will be a work truck after all. I signed the paperwork and towed my wifes GMC terrain on a U haul trailer and got 14.8 mpg at 70 mph.

I think this 6.7 is going to work out. Monday I am getting her some helper bags, a trailer brake controller, and cruise.

I'll keep y'all posted.
 
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