dodge guy wrote:
Um, no. It was 2 lanes. One slow and the other for normal speed. 60mph up a 5% or so grade is not struggling. He pulled into the left lane and could not build up anymore speed. He just hung out at the back of the X, I heard the clutch fan kick on so I know that it was working hard. So he just slowed down and settled I behind me for the rest of that highway until he turned off.
Most guys with diesels can’t fathom this story. Mostly because they don’t want to believe a gasser can do just as good as a diesel. Yes I used more gas, but didn’t make crazy outrageous mileage gains. However I enjoyed my trip just as much as the guy with the diesel did. And I didn’t feel the need to warm my truck up on an 80 degree morning either!
The fact that you said you heard his fan tells me he wasn't foot to the floor. There is no way you would be able to hear the fan over the sound of a Cummins at high load.
What probably happened was that he was too high of a gear and too low of an rpm for the pull which increases EGT's and other temps. This kicked on the fan and the reason why you were even able to hear it since the engine was not making that much noise at such a low rpm. So he backed off once he heard the fan and settled back behind you.
This actually happens more than you think on stock adaptive learning transmissions depending on how you drive. If he would have manually kicked it down a gear(depending on the year) then his rpms would have risen and his EGT's would have lowered never triggering the fan. You would have only heard the engine if this happened.