Originally Posted by Msmoto
My question is this: For those who are pulling with diesel engines, has anyone else noticed a decrease in fuel mileage over the past few years?
Of course, the wind factor may be entirely to blame, and the fact I am 500 lbs heavier may be the problem. but I was curious about others experience.
I am head east in a week, then back south east so I will reassess the overall fuel mileage once the trip is complete. I was just disappointed to be pulling at about 62 - 64 mph and have what I consider to be poor fuel mileage.
Thanks for any thoughts on this issue.
I do not currently pull using a diesel power train such as yours, I am a diesel tech and fleet manager that uses the Cummins B, C, M, and X, among others.
Yes there are many variables that are just too subjective to distill a definitive answer with some trends to graph. Very generally, AIR FIRE FUEL.
AIR: reference to condition and ability of the base engine to pump and power.
FIRE: reference to combustion
FUEL: reference to agent used to create the flame event
They are interdependent; the greater truck is an interdependent machine with the power train as it's heart.
Let's explore a scenario: a diesel power train such as yours averages x over y time fuel usage to provide you a fairly steady, normal level of performance. You're satisfied until fuel economy starts to suffer, and it's of note enough to discuss. As a tech, the systems pre-checks such as tire pressure and condition, axle alignment, service/parking brakes dragging, even just a little due to debris build-up, clean and clear engine air filtration, clean and clear cooling package fins, engine coolant condition, coolant thermostat cycle time, DPF condition (logs of cook cycles, which require fuel, like a self-cleaning oven), fuel system condition and fuel quality, any aftermarket modifications such as lifts, tires, software mods, unnecessary cargo weight...to name a few things you can do yourself.
A customer with a 6.0 years ago had a similar issue. No codes, steam, burping, ran great. It ended up being a twinkie wrapper partially blocking the big Donaldson air filter intake. Another had a 6.5 Detroit turbo diesel that was experiencing higher than average fuel consumption, with ended-up being dragging service brakes. Finally, a late Ford SD 7.3 owner was distraught that his puller had descended into the 5-6 mpg range within a 4 week period. The base engine had very high crankcase pressures, and was near the end of its service life. It kind-of was a learned compensation on his end...more and more throttle, then a spate of diesel fuel price spikes. It still pulled well (by his standards, but once in a newer unit on the lot he understood how much he had been flogging a worn-out engine. Likely not your problem, however a sensitive, observant operator notes fuel consumption, which is you.
Hope this provides some mental carrots.