How much does the fan/fan clutch play a part in fuel mileage. As some of you may know since I had this truck I have nothing but problems with bad fuel mileage. As long as I have had a Edge programmer I have noticed a fan speed control code. Today the truck was taken in to trouble shoot the code. They said it was the fan clutch was bad . So I am wondering if this could be part of the fuel mileage problem? Driving down the highway I get maybe 15mpg and towing my 20ft enclosed car trailer with a 4cylinder race car I get maybe 9. My wife and I just bought a 32ft 5th wheel, I am really nervous what I will be getting with that...

Thanks for you input.

 

CFD---The fan clutch code is a new one on me as neither one of my 5.9s 03 & 07 have any kind of a sensor on the fan clutch. Towing on the other hand and the 9MPG with a big enclosed trailer is not bad mileage with that big of a trailer with a 4 banger race car and equipment. Remember that is a whole lot of square inches which is wind drag.It takes fuel to power the pull Truck! Towing is something I do alot of with a small farm, tandem dual trailers and fifth wheel travel. I have logged over 35 K miles with a fifth wheel in tow and I have sometimes got as little as 4-5 MPG pulling through the Rocky mountains in Colorado. In general I get 8.5-10 depending on wind and weather conditions. Pulling a fifth wheel In hot weather we are talking Texas, West Texas on a August morning at 7:00 AM where it never got below 85 degrees, the fan clutch is defintely engaged and causes even more drag on the cummins. Both of my cummins dont get good mileage in the Texas summer heat. Both of my cummins do a whole lot better in the colder winter months but not as good in summer as this is due to air denisty. The colder the air temp the better they pull and the better the mileage. This may not have been what you want to hear but it is what it is............ Dont expect good mileage with a load---You have to feed the torque monster.

 

I will definitely give you "the torque monster" and having to feed it...

Thanks

 

THe fan clutch operates off of thermal expansion& contraction which makes it kick in & out when needed. I have a Edge juice on my 03 3500 and have never had any kind of issues at all with it concerning fan speed unless you have some kind of application I am not aware of that controls some kind of electric fan. Anyway dont frett about the mileage ( Yes I am aware you might have been hoping for more MPG) there making more diesel as we speak. All these old men pulling RV'S down the road know something most other people dont know,just start looking at what kind of trucks are being used in front of all those campers. Thats testement enough.

 

CFD,
I have a 2007 with a 5.9. Pretty much the same set up that you have.
I have pulled my 29' 5th wheel from Orygun to Yellowstone twice. Both times I averaged 10-11 MPG, stock everything.(Over 2500 miles round trip with several trips through the park, no trailer)

I noticed that you do not list any programmer or major mods to the truck.

I just put a 285/70/17 tire on my truck and the mpg went down quite a bit.
I figured out that the tire size wasn't the whole story. The odometer reads less miles driven but a little more fuel used resulting in 15-16 MPG combined driving.(Overhead computer)
I put the Edge tuner on my truck 2 weeks after the tires and calibrated for larger tires. It noted that it will not change the truck spedometer.
The Edge readout shows that I get around 22-25 MPG depending on what shoes I wear.
The point is if you have larger tires than stock, you will rack up less miles on the truck, and unless you have a GPS odometer, you will alwys show a decrease in MPG. The bad clutch fan will steal HP causing a true decrease in MPG.

 

Thanks to all for your input...