Mopar_Mudder

Hey thats not that bad, I pulled 11,000 with mine when stock running 75-80 and only got 7.5mpg. Their is a huge difference between running 65 and 80, it is not so much the weight as the wind resistance increase many times. For instance I have hit head winds of 30 mph or so going through Texas and had all I could do to keep going 65 mph.

Also you said that your 02 was bomed so you are not comparing equal truck the way I look at it. If you had an EZ or something of the sort on the 02 it is going to pull better then the 04 with out question.

I added an EZ to my 03 and can get 8-9mpg pulling 22,000# of trialer 10-11 pulling 17,000#, these are in the 75 mph area.

kayjh

Thanks Doug, Interesting analysis. I guess I'll go light on the pedal when I get mine. One of the reasons for going diesel with my new truck instead of with the Hemi (in addition to the obvious towing capacity) was the perceived fuel cost savings. Everyone I have spoken to has reported horrible fuel mileage while towing with the Hemi.

doug

I do believe the fuel economy gap between gassers and diesels is narrowing, but we still have the advantage. For example, my cousin has a 31' motorhome, sporting a 325HP Chevy 500 ci large block. 9 mpg. CTD guys with 31' 5vers are getting at least 10-12 I think. thats ~ 30% improvement.

you made a good choice on the CTD instead of the hemi. the Torque is just not there -- it takes what, something like 4500 rpm to achieve rated HP. the CTD can make 305 HP at only 2900. you'll also love the low speed fuel economy of the diesel. I ran empty through the mountains once from N Idaho about 75 miles at 5-20 mph before catching pavement, then all the way back home ~ 500 miles total. 19.7 mpg hand calculated.

Vaughn MacKenzie

My 3500 SWR 4x2 I generally see right at 20 MPG when I cruise at 78-80 MPH. If I have the patience to poke along at 70 it's around 22. 65 is out of the question since Walla Walla is about the only place I go where I go that slow. When you're out in the middle of nowhere you don't got all day to get somewhere

Some of you guys towing hard and heavy with less than 1000 miles might be overdoing it a little. I don't think you have to go gangbusters for proper break-in. I didn't tow much until 5K miles and haven't towed much overall, but at 16,000 miles she's running mighty fine now and is ready for that synthetic lubrication

Vaughn

Scotty

I am averaging 16.8 empty with an 04' 3500 4x4 6 spd with 373's.
I averaged 13.6 with the 24ft v-nose enclosed tag trailer and it only dropped less then a mpg with a 55 Chevy Bel Air in the trailer!
I drove at 2000-2125 rpm the whole way.
I only have just shy of 2500 kilometers on the truck and it definately felt stronger then Rods truck stock.
I droe the truck easy for the first 500 miles, then I worked it a bit on some hills with the trailer empty and then I worked it some with the trailer loaded.

Now I will dump the oil and go again with the load for another 500 miles on the wknd. :'(
This truck is a complete and total difference from my 01' for handling, braking and power.

I am currently running with an old non adjustable EZ and the RAM AIR 3 that sucks COOooOoOoooL AIR. ;D

Maybe theres a difference in mileage from the different transmission combinations?

Mopar_Mudder

[quote author=Scotty link=board=20;threadid=19346;start=15#msg190926 date=1064933559]
Maybe theres a difference in mileage from the different transmission combinations?
[/quote]


Hey Scotty your milage is about dead on with what I get, which is good to here because all theese people getting 22+ have me thinking I am going nuts.

Every day driving empty I always get between 16-17. Straight out going down the highway at 75 empty it get from 16-17, get over that 75 and it drops fassstttt.

Towing my 40' flat bed empty (10,000# aprox) I get around 12 mpg. With 2 cars on it, a 66 Chevelle and a 67 GTO, I got 10 mpg.

Through my 2 off road trucks on the trailer, 76 Ramcharger and 83 1 Ton, I got 8.5 this last time out, that was mostly 60-65 mph. I know that if I run that load down the highway at 70-75 I drop down to 7 mpg, but that is 31,000# GCVW and they sit way high on the trialer with 40" tires, but man do it look cool 8)

Scotty

High profile will always kill mileage...probably faster then adding weight...at least that is my experience.
I did notice that same thing...going even 5 mph past that 2125 rpm range and my mileage drops FAST!
I can live with that.

;D

P Kennedy

Why do you guys worry so much about the breakin, a loaded tandem gravel truck is 40-45000lbs. Different truck manufacturers use the B5.9, C8.3 & Cat 3126 in tandem or smaller configurations and breakin is not an issue. These units are bought, rigged up and sent to work. Take for instance a city/town service truck setup it would hit the streets and be loaded numerous times per day possibly 30-50 loads before the 500 mile mark. I encountered a situation a few years ago when selling Kenworths where a buyer refused to pick up his custom ordered truck unless it was the tow rig under the 2 others piggy backed. Kenworth did a study of towed vs towing of new trucks and the tow unit always had better breakin results, the sooner you could generate heat and stabilize the block and it's components the better the engine ran with less oil consumption. I think this system of breakin is another 1950 gas engine concept and would rather see hot breakins than cold driving like some people here do to warm up quicker. PK

doug

If memory serves, its not the engine that requires the 500 mile breakin; its the other driveline components. Indeed, the manual recommends towing during the first 6,000 miles after breakin. I think the 500 mile thing is a compromize that lets the rest of the driveline wear in properly before you unleash the cummins.

kayjh

[quote author=P Kennedy link=board=20;threadid=19346;start=15#msg190947 date=1064938320]
Why do you guys worry so much about the breakin, a loaded tandem gravel truck is 40-45000lbs. Different truck manufacturers use the B5.9, C8.3 & Cat 3126 in tandem or smaller configurations and breakin is not an issue. These units are bought, rigged up and sent to work. Take for instance a city/town service truck setup it would hit the streets and be loaded numerous times per day possibly 30-50 loads before the 500 mile mark. I encountered a situation a few years ago when selling Kenworths where a buyer refused to pick up his custom ordered truck unless it was the tow rig under the 2 others piggy backed. Kenworth did a study of towed vs towing of new trucks and the tow unit always had better breakin results, the sooner you could generate heat and stabilize the block and it's components the better the engine ran with less oil consumption. I think this system of breakin is another 1950 gas engine concept and would rather see hot breakins than cold driving like some people here do to warm up quicker. PK
[/quote]

Here's why:

"During the first 500 miles (805 km) your new vehicle is driven, do not tow a trailer. Doing so may damage your vehicle.

Limit your speed to 50 mph (80 km/h) during the first 500 miles (805 km) of towing"

(2004 Ram Truck Diesel - Owners Manual - Page 66)

While the "super human" Cummins engine doesn't need any special break in, I guess the merely mortal drivetrain does.

For me, it's not big deal. I just avoided towing for the first week. For a vehicle with a lifespan of at least 350,000 miles (before engine overhaul), who needs to listen to loud differential, transmission and transfer case gears. Even worse than the noise would be letting the dealer loose on my truck to try and fix a loud differential. Some of them have difficulty changing the oil correctly!

doug

[quote author=kayjh link=board=20;threadid=19346;start=15#msg190954 date=1064939624]
For a vehicle with a lifespan of at least 350,000 miles (before engine overhaul), ...[/quote]

just to be picky here, but if memory serves, 350,000 miles is the average life between rebuilds for the 5.9L ISB, not the minimum lifespan.

Mopar_Mudder

[quote author=Scotty link=board=20;threadid=19346;start=15#msg190932 date=1064934779]
High profile will always kill mileage...probably faster then adding weight...at least that is my experience.
I did notice that same thing...going even 5 mph past that 2125 rpm range and my mileage drops FAST!
I can live with that.

;D
[/quote]

I have also noticed that wind resistance is worse then weight. I have also found out that you guys pullin campers have it easy. Friend of mine hauls around camper for a living with his Ford, he hooked on to my off road truck on a trailer once and couldn't believe how much harder it pulled then a equall weight camper. Even though they look as aerodynamic as a brick I guess them boxes do a good job of breaking the air.

kayjh

[quote author=Doug link=board=20;threadid=19346;start=15#msg190971 date=1064941746]
[quote author=kayjh link=board=20;threadid=19346;start=15#msg190954 date=1064939624]
For a vehicle with a lifespan of at least 350,000 miles (before engine overhaul), ...[/quote]

just to be picky here, but if memory serves, 350,000 miles is the average life between rebuilds for the 5.9L ISB, not the minimum lifespan.
[/quote]

Doug, Not to be quibbling with a 5 star member , but I guess what I was getting at was the truck is going to be around for quite a few years for most owners and the engine is expected to have a mean time between overhaul of 350,000 miles. True, some will last longer and some will pack it in earlier. But, to me that is the minimum life for a well cared for engine. The guys who take care of them will get more and the guys who abuse them and don't service them will get less. There really is no minimum life if you want to get picky. Just drain the oil and drive it and it will last 3 blocks!

Our company Fleet Ram Vans are equipped with 5.2L gas (and some propane) engines. I'm not sure what their MTBOH (mean time between overhaul) is, but I'm sure it's less than a diesel. We have gotten an average of 350,000 KM on all of our trucks with no engine overhaul required (10 of them in the fleet). In fact, the most we've had to do is general wear and tear maintenance and front end/brake work. So I feel comfortable that the wording I used is likely representative of what the minimum life of a properly maintained Cummins will be.

As to Diff fluid levels, I may stand corrected but, AAM issued a bulletin to clear up the confusion over diff fluid levels. If memory serves, the 11.5" axle is spec'd at 1/2" below the hole +/- 1/4". So, the maximum fill would be 1/4" below the hole, not at the level of the hole. I think that if it didn't make a difference, AAM need not have issued the bulletin as that was what everyone was complaining about; that their diff's were delivered low on lubricant. AAM was stating that 1/2" below (plus/minus the allowed variance) was acceptable and that overfilling would lead to the undesireable foaming condition.

I'm no expert, so I just follow the manufacturer's directions and hope for the best. If I'm wrong (and should have overfilled), I have a warranty. If I'm wrong and did overfill and a failure results, who knows what I've got?? (I suspect - trouble).

doug

hey, kayjh, no argument from me on the lifespan. My comment was really a mathematical one -- in order to publish "350,000 miles average" between rebuilts, Cummins has to do some pretty hard reliability number crunching. so thats just a mathematical prediction. What YOUR engine will do is just part of the statistics.

hmmm. on the diff level, it looks like the AA buletin as you have described it, and the RAM owners manual, disagree. The manual says 1/4" below the fill hole +/- 1/4", which is of course what the DC warranty (the one that benefits us) is based on.

On the other hand if AA has a different spec, then they might hold DC accountable for mis-informing their customers. Do you have any references back to this bulletin you refered to?