If everything is working properly on your D, you really should never encounter any overheating problems, even in the hottest weather on the longest grade. NOTE - Well, may that is a bit of an overstatement. At higher altitudes where the air is thin, the ability of the atmosphere to accept heat is reduced, especially if the ambient temperature is hot. So, under these conditions the coolant may reach 210 degrees Fahrenheit, which is the trigger point for the "Check Engine" or "Stop Engine" lights. If this happens, try downshifting and operating at less than full throttle. It is best to monitor your coolant temperature with your VMSpc and take action to prevent the coolant from rising to 210 degrees. Cummins is very specific about the cooling requirements of their engines and requires every motorhome manufacturer that uses their engines subject each model to a strenuous test before Cummins will allow them to use their engines. It appears as if the radiator has been increased in size on late 1999 model D's.
So, what if you have an overheating problem?
Here are some things to check:
This is not meant to be an exhaustive list of possible problems. If you want to contribute other ideas, please advise the webmaster.
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