I am having an overheating problem in my Dodge D350 diesel. This started about a week ago or so during a 400 mile tow. During the tow I was able to get up to 70 mph and cooled the pickup down but now this does not work. My heater no longer blows any warm air in the cab and the pickup will not cool down. I have replaced the thermostat but this has not helped. There is also plenty of coolant in the radiator. Additionally the radiator is cool to the touch when overheating, and the pickup does not lose any power. Does anyone have advice on how to fix this problem of mine?

 

Sounds to me like a classic case of water pump failure...especially as you say the heaters in cab are not warm.( no circulation)..

 

I agree, the water pump is kaput. It could be the impeller actually rusted down to the point where it can't move the coolant any more or the impeller fell off. Eaither way, it is simple to change. The esiest water pump you'll ever change. 2 bolts and and o-ring (no gasket to scrape). It's more difficult to deal with the belt.

Chris