Under a load the engine temp will creep up past the 0 on the 190 before what seems like the thermostat opens and then things cool off to 185. Sometimes the temp stays warm, other times it bounces between what seems like 185 and 210-215.

When towing the engine gets too hot and I have to pull over and let it cool. This happens when going over a steep grade however straight line towing keeps the temp between 190 and 210 normally.

Now, here's what I've done to troubleshoot:

I've changed the radiator cap, thermostat, belt, had the radiator cleaned out by a shop because it was nasty, and I left the cap off the radiator until 190 when the thermostat opened and the level inside the radiator dropped in half and seemed to have good flow.

Now, I don't know what else might be causing my cooling issue. Talking to a couple people who are diesel mechanics they mentioned these things.

The truck may be running lean for various reasons which would cause the heat generation, however the dealer said this was a far stretch.

The coolant may be staying in the block too long, which would cause the temperature fluctuations and would cause the fan to not come on because the radiator would be cooler.

The clutch fan may not be properly working. I asked the dealer at what temp the fan should kick in, and they said there was no set temp. Now, this strikes me as odd because mechanically speaking there has to be a point at which the fan should turn on and off.

Aside from this, I'm at a loss of what my problem may be. If anyone has an advice or troubleshooting tips please let me know.  

mine will run up to 205 to 208 seems like but if your thinking your fan is going out put in a set of electic fans there suppose to even help mileage taking less  stain off the engine they run up close to 600 dollars thogh  

Mine cycles the temp exactly the same way. The owners manual says this is normal. I've got the flex a lite electric fan #262 and you can set it at what temp it comes on or turn it on with a switch. I also have a new rad.  

Check your fan clutch, mabey its not engaging like it should?  

wwwasteelsolutioncom is thinking the same thing as me.I would get your fan clutch checked out.By someone else other than a dealership.Is their a shop that specializes in diesels in your area?Because when a truck rolls in where i work with an overheating problem, one of the first things we look at is if the fan clutch is engaging at all or at the right temps.And i would also get the thermostat looked at to see if it's opening at the right temps.  

Yeah, I was thinking it was the fan clutch too. The first time it overheated the fan was on and running, although the radiator was pretty dirty then so maybe it was just a combination of problems. I did replace the fan clutch last night and today I'll be able to test it. So far I've changed everything in the cooling system aside from the water pump and that looks like a 30 minute job because it's so accessible.

I'll let you guys know what I find out today, and thanks for the advice.  

mine does the same thing. i put a new thermostat in it and a new fan clutch. and it didnt change anything. mine will get up to around 210 to 215 pulling a heavy load or running around in town. but once on the highway it cools back off but i wont ever get above that so i just kinda quit worrying about it since it doesnt ever go over that.  

Well, I changed my clutch fan and also replaced the diff oil with synthetic. I've replaced everything in the cooling system except for the water pump because I can see it working. Hopefully this fixes all of the problems I've had. I'll find out this weekend when we move out of state, there's some good mountains between California and Oregon.  

take your thermostat out completley and see if that helps keep a consistent temp....itll just take a little while longer to warm up  

rhoadesy:
take your thermostat out completley and see if that helps keep a consistent temp....itll just take a little while longer to warm up

I don't see how this would help, in fact running the cooling system in an open loop is bad for the engine. I've changed the thermostat, the old one wasn't bad I tested it. When the temp hits 190, which is the opening point I get good flow in the system and the temp drops.