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Discussion Starter #1
Looking for some help from you guys, I am a Dodge CTD owner and have just purchased my wife an 02 Duramax. Can you guys tell me any of the issues I should look out for? How can I find out how many hours are on the truck? Etc. Thanks in advance
 

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Injectors are the only common issue with duramaxs. If you have problems under the 100,000 mile warranty GM will replace all 8 injectors. You might want to look into adding a secondary fuel filter.


To see how many hours, when the key is off hold down the trip odometer reset for 3-5 seconds.
 

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Thanks, I am really looking foward to see how the Duramax pulls my 5th wheel. So far love the truck and the allison seems to be really smooth. I am a Cummins man to the bone, but this Duramax could change me if it gives me as good as service as my 10yr old Cummins has. By the way whats the average fuel mileage?
 

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~20 empty Depending on how you drive it.
 

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I've seen anywhere from 10 mpg pulling my travel trailer to about 17 mpg running about 75 out on the highway. I've got just under 12K miles on mine. I've seen a lot of posts with higher fuel economy, but I don't believe everything I read. These trucks are not aerodynamic and pushing 7000 lbs, 15-16 mpg ain't bad. And oh that power.
 

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Good luck with the new Duramax... If anything can change your mind, the DMAX is the ticket.


As for mileage, I just ran down from MI to Georgia and averaged 20.7MPG pushing 70-75mph all the way, nothing fancy, nothing tricky. On my way back, I averaged 11.3mpg pushing 70-75mph, but pulling my new 30' 7000lb travel trailer.


Hope this helps...
 

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Discussion Starter #7
WOW only 11.3 with 7000lb. I have a 10k lb 5th wheel and with the Dodge I get 14.7. I hope the Max gets near that.
 

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BOZ_UT said:
WOW only 11.3 with 7000lb. I have a 10k lb 5th wheel and with the Dodge I get 14.7. I hope the Max gets near that.

Just depends how fast you go. I get around 14 mpg pulling 8500# of 5th wheel at 68-70 MPH. Ran 78-80 MPH with it one day and got 11.2 MPG . . .the speed difference hardly makes up for the extra fuel stops.


I don't generally exceed 75 MPH, and I never do worse than 20 MPG without the trailer. (OK, 1 tank was 19.7, from Longmont, CO to Rock Springs, WY, westbound, ground speed = 75 MPH, airspeed = 100+ MPH).


Some folks may be sceptical, but I keep a spreadsheet with every expense logged for the truck. I've sent it to a couple people who wanted to see it. Just ask.


Do note that mine is 2WD and 6 speed, so its weight and parasitic losses are minimized. Also it's a GMC, so it has better areodynamics.
 

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I agree with Colorado Kid, it all depends on how you drive and where you drive. I tow a 7K TT with the majority of my trips between Portland, OR and Albuquerque, NM. There are a number of mountain ranges to cross on this route and I run about 5-10 MPH over the speed limit even when towing. I have kept my milage log since the truck was new and broke it into 3 categories: Towing, Road Trips, and Normal.



Normal Milage: 17.1019 for 15719 miles


Towing Milage: 11.997 for 6271 miles


Road Trip Milage: 20.0154 for 7566 miles
 

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i think everybody looks at the dic and thinks there getting 20 miles a gallon but i wanna know how many miles there getting per tank ?
 

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That's bettewr mileage than my Z71. I was reading a post on here yesterday and the guy was saying about anything above 500 rpm you can watch the fuel gauge go down. Tell me that isn't true. If I punch my truck everywhere when I drive I can watch it go down but that's on any vehicle if you dont drive normally. Does the Dmax really redline at 4000 too?
 

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better
 

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Below 500 rpm and the truck won't run. I don't find it makes a whole lot of difference how I drive. It does make a difference but not as bad as a gasser.





I don't remember exactly but I redline is somewhere around 36 or 3700 rpm.Edited by: Max Power
 

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I average 15-16 city highway mix. I'm juiced and have a very heavy right foot. on the highway I ussually set the cruise to 70 and forget about it. Uni airfilter and a 4"-5" Kennedy exhaust with no muffler. reg cab 4x4 alli tool box backrack and a fullsized lightbar. 265's for tires. milage calculated the old fasioned way. FTTP additive


I think the worse I ever got was 12 and that was plowing snow with lots of idle time and me driving like a maniac with a 9'6" snowplow up front and 1000#'s of ballast in the back


the dreaded NSBU switch too. Hopefully the switch on the side of the trans is tan in color and not black. poke your head underneath the truck and see if the box thingy on the driver side with some electrical plugs going into it and the shifter linkage stuff is black
or tan
.


I would change the fluid in the front diff and every place else. Do a serch about synthetic breather caps if you want to go to synthetic in the front diff. Change the fuel filter too for grins.....no telling when if it was done last. And when you change the spin on filter for the allison dont pitch the little doughnut magnet on the filter! I would only use allisons synthetic(if you want to go that wroute) or regular old dino dexIII. I would stay away from other peoples synthetic even if it says its dex III compatible
 

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From what I have heard and observed, the DMax's "sweet spot" is between 1800 and 1900 RPM. I have found that I will get the best highway mileage when I set the cruise control so the RPM's are just below 2000 (I'm not listing speed due to different gear & tire combo's). If I follow this mantra, I typically average 20 MPG, calculated by me at fill-ups, not a DICk. If I run the same stretch of highway at 75+ MPH, my mileage definiteley goes down a couple mpg.


sloth
 

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Hey, all. The 500 RPMS was posted by me (my own opinion) Running at about 2500 RPMS, your milage drops off. Running about 2000, or a little less (like Sloth mentioned) is where the best economy seems to be.
 

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How many times every day would you run at 2500rpms? What is that like 65 or 70. Does that Dmax idle at 800 or so.
 

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65 is about 2000 rpm. And I was wrong earlier. Redline is 3200 or 3300 according to the tach.Edited by: Max Power
 

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Adam,


The Duramax idles at 650rpms... Max is right about cruising speed... and about the 2500rpm thing, that is true with any engine... the dmax redlines at 3200 or 3300, so 2500 is getting close to redline... same would apply in your truck if redline is at 4500 and you ran at 3700, you would eat fuel. Don't get me wrong though, you will be running in the 2500rpm range a lot when shifting up to cruising speed, but that's not what will suck your fuel down... now if you are running 80 or above at 2500rpms or so, then yeah, you will be filling up every couple of days.


Dan
 

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I cruise between 75 and 85. Now n then I see 95. Pulling away from stop signs or lights I'm like a kid with a hot rod. I'll be 54 next week. I know better, but this power is adictive! I obviously don't try to get the best mpg outta this thing. I moved up from a 95 Suburban gasser witha 350. I can hot rod this thing as much as I want and still get much better mileage out of it than than 350. I did take it easy for one tank and got a little over 20mpg but it just wasn't near as much fun.
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