Ok so got back from a trip towing my 26ft 5ver. The thing weighed 6,500lbs on the way home & I had a full tank when we left minus like 15 miles.

We stopped in Warm springs and my trip computer read 249.8. I filled first thing this am drove directly to a fuel station and the trip computer read 111.7. We used 42.76 gallons of fuel for the trip.

Total mileage was 361.5 per the trip computer.

Our total cost of fuel was $171.01. Mileage on tank one was 8.6 and mileage on tank 2 was 8.1 and we coasted down hill half the way.

So if I add 10% because of the tires we get 397.65 miles total…Divide that by 42.76 and we get a whopping 9.2MPG.

This is downright pathetic to me. I want to be excited about the Dodge and this legendary Cummins but truth be told the thing is just a thirsty pig of a truck so far. My F250 w/ same tire size and the 6.0h no, routinely did better on fuel even draggin trailers w/ 3 roadracebike tools, and a sidecar weighing more than 6,500lbs. It never did below about 12 MPG no matter what I put behind it (I hand calculate all miles in my trucks and fill to the same spot every time no exceptions). I don’t know what to say? The truck transmission also ran hotter than I feel it should have on the way there. There is absolutely no reason why my transmission should get to 250 degrees towing 6,500lbs up a hill. It was flushed recently and filter replaced, fluid level is in spec. Add some higher temps not the 34 degrees we had and we would have had to have pulled over and parked and waited.......This is completely unacceptable to me.
oh and EGT's will go beyond 1200 degrees on the hills if I were to allow the truck to do it. This could happen very easily. Glad I have gauges if the stock Dodge can run hotter than it should from the factory.

So there it is my vent from my trip this weekend.

I would be curious to hear your results. 40K miles on the truck.

 

You need to go to the dealer and get your truck flashed for the larger Tire size. Adding a % is just more of a guess.
Running 1200 EGT is normal, 1350-1400 is when you should worry.
A tranny above 250 is a serious problem.
Where do you get that reading from?
At what speed were you at?
How steep of Hill?

 

I pulled a 4 horse trailer with 5 horses stuffed in it, all the gear for 6 horses, 500 pounds of feed/hay, 4 guys and 7 dogs from Columbus, Ohio to Nashville, TN. Down and back hand calc'd we ended the trip averaging 16.5mpg doing 65-70. My trans temp never went over 130 and EGT's never got over 1100. Total weight we figured was somewhere around 12,000.

First off that tranny should never see temps in the 250's above 190 and your cooking your fluid. I think that with the 315's and 2" lift your already adding strain to the trans, then add a 26 foot 6500# trailer...not sure what the answer is you might have some injector issues, maybe even a slipping tranny thats causeing the excessive heat...either way you should be seeing better mileage than what your currently getting.

 

Just a thought your 5ver has a larger surface area causing more drag then your motorcycle trailer. Just a thought.

 

Guys I totally agree. I have a trans temp gauge in line. I got the setup from Dieselmanor.

It reached 250 going 40mph over a pass. I had no options to pull over or stop.....Traffic was moving slower than I would have liked as it started snowing..... I guess I will drop the pan and replace fluid a couple times.

In my Fords the do not exceed was 220 degrees and I never got close. This Dodge will do 180 unloaded in town.

Any input on what I need to do regarding trans temp?? This does not seem normal to me. Anything I could check for? Could my trans sender be wrong by chance?

Stumped.

 

Yeah your right it does but the 16ft trailer is extra height and I have weighed it and it has been over what the 5ver is. It also could be that here in the NW every direction you go is up! Beautiful place to live been here my whole life but we dont have flat roads Lots of mountains and lots of trees.

I guess that could attribute to the lack of economy. Transmission shifts firmly and doesnt do anything weird???

Was thinking about a Smarty or Jr eventually but truck is stock except for the BFG's.

 

What gear were you in when going up the hill @ 40 mph. I will usually shift into 2nd, & the T/c will lock up somewhere over 30 mph. This will lower your tranny temps a lot. & with my 285/70's I can easily go a little faster if I want to in 2nd gear.

 

My boat weighs #6300 lbs and even cruising at 75 mph got over 11 mpg. I can crowd 13 mpg being nice and travel 70 mph and I can get somewhere around 11.5 mpg driving 75-80 mph. The boat may have better airflow than your rig but I get 22% beter than you. The difference in tires from 315 to my 265 is 0.9186, I normally tow at around 70 mph and keep the motor to just under 1900 rpm. The real concern should be your transmission. Going up hills in the Ozarks a few summers back the transmission never increased in temperatures once it locked up. Only once did the temperatures get to 180 and that was in the city with hills, stop & go traffic 95+ heat and me driving with a too heavy foot. So your 250 temperatures appears like the transmission is slipping creating excess heat and mucking up your mileage. With your tires you should be indicating 64 mph to travel at 70 mph. You didn't say what speed you were going on the trip. But if you were indicating 70-75 that may account for the transmission and mileage. JMO

 

16,000 pound very high 36' fifth wheel, stock tires, 4.10 rear end, 6 speed stick. Alaska and back 17,400 miles - - average for trip, 12.8. Newfoundland and Mexico, 13,000 and 13,900 - - 12.6 for the trip. Sure, EGT's will go up if I push it without shifting, but I can hold them at 1250 on the upgrade regardless of the slope including 12% in Newfoundland. I run 65 on the interstates. You have something wrong - - I can sure whup the Chevs and Fords on mileage.

 

I am reading/searching and realizing maybe I should have manually shifted into 2nd.

I have also heard that 250 isnt that uncommon for a short burst towing up a grade.

Our speed limits here are 55-60mph and I dont drive any faster generally. Maybe short bursts but I am not sitting at 65-70+ but more like 50-60...I try to keep rpms below 2K.

So if this is not right where do I begin to find the issue?

Fuel filter changed 5k miles ago, air filter replaced 5k miles ago.

 

Hand calculated to same spot in tank each fill? I can get 4 gallons extra in tank once it clicks off.

Is yours a 4x4?

 

2 trips to montana pulling 9000# 5th wheel(2004 couger 314) averaged 12 mpg round trip both times.I can also pull Donner at 55 mph in 5th gear.I figure im close to 18,000# truck, trailer, and gear combined.

 

Can anyone tell me what may be causing the mileage I am experiencing?

 

9.2 MPG, 250* tranmission temps, towing 6,500 lbs at 55-60 MPH sounds like either your TC is slipping or not locking up.

A 04.5 and newer truck can run EGT's of up to 1450* for long periods without harm. The engine is designed from the factory for higher temps than it's earlier little brother. They use different programming to determine approximate EGT for defueling.
The 48RE transmissions use synthetic ATF+4 because they run hotter than previous models. Up to 200* is acceptable. Even higher for short periods.

Last year I drove my truck in 117*F for 100 miles towing my 12,000lb 5th wheel at 65 MPH and the transmission never went over 196*F. I also average 13 MPG at 65 MPH.

 

Hand calculated on each tank fill - - heavens no. Filled when I leave the house, all purchased gallons logged during the trip, filled when I return home. Then I hand calculate for the total trip. Ironically, every time my computer was no more than .2 mpg off, one time high, another .1 low. It is almost impossible to fill our tanks to the same spot every time unless you sit there for ten minutes while it fumes and fusses. This means individual tank mpg calculations can be quite different. The total trip of thousands of miles is the most accurate measurement. I sure do not understand your mileage problems- - the Cummins is always better than the "other" two. What are you getting running solo?

I am NOT 4x4.

Bob