thanks for your post, I have exactely the same problem with a side radiator. Is yours a side rediator as well? thanksA very sharp Cummins Guy has finally found my overheating problem...I think.
I was going to install the Source Engineering Wax valve on the engine. The tech suggested that before we get deep into that install, he wanted to check a few settings in the ECM. He connected the shop laptop running InSite and started checking the fan settings in the ECM. There is a specific test that InSite runs that cycles the fan to different speeds by changing the percentage of ?Commanded Fan Speed.? With the type of fan control that I have on this coach, there should be only two speeds, low and high. The percentages set by the test should be 100% and zero %, so the fan runs on low and high speed. However, when he ran the test, InSite cycled the percentage between 100% and 50%! As soon as he saw that he said, ?That?s not right. That?s the test for a variable speed fan. This is a two speed fan system.?
He then checked another setting and discovered that my fan system was set to ?Variable Speed? in the ECM! THAT?S WRONG!
He changed the setting to the correct setup for my 2-speed controller and ran the test again. A moment later I heard a sound I have never heard before. It was the roaring sound of the fan running on high speed! How about that! I?ve owned this coach for 6 years and had never heard that before! The fan was plainly audible inside the coach, too.
On the way home, I purposely beat on the coach hard, to see what would happen. I hammered up one grade at 70 mph with my foot on the floor. The temp had been running around 205. It quickly climbed to 212 and then, with my foot still on the floor, beatin? on that big ol? Cummins as hard as I could, the temp started coming DOWN! It dropped back to 207 and stayed there, even with the throttle wide open. It had never done that before! Prior to this, if the temp got up to 212, the only way to get her to cool down was to back out of the throttle, slow down and shift down, to keep the RPM up around 2,000.
I think my overheating problem may be solved...finally.