Found something neat out today. As you all may or may not know, I don't run a fan or anything. Obviously this poses a problem while idling. It takes about 10-15 min of idling to get it from 190 to 210. I am not sure why this has never crossed my mind since it is probably a well known fact but they say to run the heater when the engine is overheating. I got back today and let it idle with the heater on full blast. It never moved from 190, in fact it went down to 190 (was at 195) and stayed there for 10 minutes that I trial ran it. I have 2 temp gauges and they both stayed right there. That means if I idle, all I have to do is roll the windows down and put the heat on full blast and won't have a problem. Interesting how a little heater core can dissipate all the heat created by the engine at idle.

EXACTLY!!!

These engines don't produce much heat at an idle. That is why Cummins does not recommend letting them idle and also why you need to use a fast idle. That little heater core is capable of removing more heat than you engine makes at an idle.

I am surprised your truck stayed at 190, mine cools off at idle even on a hot day it will drop to 180* in no time flat, and sometimes lower. Remind me why you don't run a fan?

I am surprised your truck stayed at 190, mine cools off at idle even on a hot day it will drop to 180* in no time flat, and sometimes lower. Remind me why you don't run a fan?

Mine stays at about 195 once you drive it long enough. My idle did the same thing when I had the fan on. I took it off originally just because I heard a rumor that it takes power/mileage away. I think it is negligible but I gained a ton of room by getting rid of it and the shroud. I work on my truck a lot just to be working on it and having that crap out of the way saves me a lot of time since I don't have to take it out constantly. The only thing I see as being a problem is the underhood temps when your not moving. I have a temp gauge in there and have seen it get pretty hot under there. I worry about things melting, but after a year it hasn't happened so I pretty well stopped worrying.

Mine stays at about 195 once you drive it long enough. My idle did the same thing when I had the fan on. I took it off originally just because I heard a rumor that it takes power/mileage away. I think it is negligible but I gained a ton of room by getting rid of it and the shroud. I work on my truck a lot just to be working on it and having that crap out of the way saves me a lot of time since I don't have to take it out constantly. The only thing I see as being a problem is the underhood temps when your not moving. I have a temp gauge in there and have seen it get pretty hot under there. I worry about things melting, but after a year it hasn't happened so I pretty well stopped worrying.

yep...that is why race cars,drag car,etc etc run electric fans..anything that takes a belt to run it robs horsepower.kinda vearin' out the subject here..but i tell people when ask my opinon on..should i supercharge my car or turbo charge it?TURBO IT!!it is free horsepower...