I bought a new 2009 that I picked up in Jan. '08. I drove it to Arizona and back to Washington, and noticed that it ran (200 instead of 180-190) a little hotter than our '06 used to run, especially up hills. It turns out that the radiator fan was running the wrong way, pushing hot engine air out through the radiator instead of pulling cool outside air through the radiator from the outside.
Talks with Cummins and calls to Burk Morgan and Dave Frampton got me the to the vendors involved. At first I thought the fan blades were pitched the wrong way. The 9-blade fan vendor is Multi Wing (800-311-8465). But we actually determined that the fan motor (what I would probably call a hydraulic pump) is a bi-directional motor (mine had a part number SNM3-33) from Berendson (800-360-2327 or 918-581-5116). We were able to turn the fan motor upside down and attached the input/output hydraulic lines to the opposite sides, therefore making the fan run in the proper direction. Berendson also makes the HCI controller that controls the speed of the fan, if anyone needs one.
Just thought I'd pass this on. My guess is that the same setup has been used for years and if you feel air coming out of your radiator instead of sucking in....check it out.
Actually, it shows how well these things cool since I stayed less than 205 degrees most of the time (according to my silverleaf) although I admit that I didn't ever have to drive in real hot weather. I suspect that I'll run much cooler now, even down in Arizona.
Heading to Arizona tomorrow.
09 Alpine Limited SE 36FDTS
14 Chev Silverado Toad