Yep, same boat here. I have replaced the water pump, radiator,fluid, cap, clutch,t-stat, cleaned other coolers too and have the same exact problem you do. Don't bother wating your time and money changing it out. I already have. Check out my thread. I have done everything you have. The guage is probably not lying to you either. I installed an aftermarket temp guage and it did not lie to me. It is definitley roasting hot. I have tried many different remedies to cool my rig down. I am not overloaded either. I have seen what these trucks are capable of. Mine just isn't.

If you have any suggestions, hell I will try anything at this point.

Your EGT's are relatively low though for pulling a grade. Are you post or pre turbo on your pyro?

 

Post turbo
I still would like to know why the 1 ton rad has a different part number. Have you looked into this?

 

thats really strange only hitting 700 on the pyro when pulling a load and a hill! heck mine unloaded acceleratiing from stop to 30kph will hit 700+.
All I can think is at 2800rpm your cavitating the pump, or the thermo is bad, what brand thermo is it ? if MotoRad (I think you can get them for a cummings) get rid of it cause they are junk. also soft lower rad hose can suck shut causing overheat issues at higher rpm. can you see in the rad? I've seen calcium build up that near completely blocks off the rad tubes

I'm basing my experience on autos in general not cummins specific.

With your handheld temp gun measure the temp at the rad and at the block/thermo housing. if the rad is the same temp as the block, then its overheating, but if the rad is cooler then there is an issue with thermo/pinched hose/cavitating

also try pulling the same hill in OD to keep the revs down and see what happens, I dont think at 700EGT your engines making enough heat to overheat, its gotta be a faulty part of the cooling system

 

Definitely check your thermostat. A buddy of mine had a '99 that he pulled quite often with it. He had a couple of cases of the frame on the thermostat breaking causing it to not open fully. Running around empty or with light loads, you would never see an issue. But as soon as he put a heavy load on, it would overheat.

 

#1 PUT THE PYRO PRE-TURBO. Post turbo, account for another 300* additional, so your at about 1000* pulling, which ain't too bad anyhow, but i was rammed by these guys every time I said I was post turbo till I changed it over. There are many threads and opinions on how to do this on this site. Don't waste your time pulling off the turbo to avoid getting steel in it. I used a drill slowly with grease to catch some metal, and ran a small magnet inside after I tapped the hole.

I just ordered another fan clutch. Cummins replacement. RickCJ has recommended this to two or three times. I think this actually might be it. He said it should sound like a jet under the hood when the engine heats up while pulling. Mine doesn't... I don't think, with 5'' stacks, no silencer ring and a cold air intake, Its LOUD anyways. Make sure your t-stat is a cummins replacement as stated above.

 

Yeah I know this forum likes pre turbo but why do class 8 trucks (Pete, KW, Freithtliner ect.) all install the thermocouple post turbo?

One thing you are all missing is as I said If ambient temp is below 20 celcius It doesnt overheat. This is why I think it is a rad heat rejection issue.

The t-stat is a cummins part. I may think of changing it, I would like if someeone could answer my original question. "Why does a 1 ton rad have a differnent part number?"

 

Well did the same trip this weekend on the hill where it would overheat. Well it did not overheat. I was 2000 lbs lighter temp was 18c (64F) coolant temp got to 212f and I confirmed that with a Raytek infared temp gun.

 

did you measure the rad and the block to compare the differences? lower rad hose should be noticably cooler

 

I noticed that my engine would start to warm up if I go over 2,500 rpm so I usually tow at 2,200 max sustained. Below 2,500 rpm it does not go over the vertical mark on the factory temp gauge.
Taking out the radiator and washing off the large ring of crud off the front side of it was the best thing I could have done to the cooling system. Replacing the t-stat is a prudent thing to do I think, they are a maintenance item anyway.
I recall hearing that factory tow package included "larger capacity cooling system" like a 2-row vs 3 row radiator? I may be barking up the wrong tree here....

 

When I bought my 2002 3500, seems like there was an option for heavier/larger cooling system, so maybe there is a larger radiator. It is routinely 33-38C here in the summer. I pull our 14k fiver mostly on flat ground. The Temp needle gets just over 190 and stays there, or drops to 190. That seems what they mostly do. 180 Tstsat is an option too, although not good for winter.
You could try slowing down some, too. I know that is no fun.

 

Yes I did and the bottom hose was 30 degreese cooler. No overheat and all will make temps look good. I will get one more try at it this upcoming long weekend bigger load this time 5ver and quad trailer with two quads.

 

Yes I considerd a cooler t-stat but others are towing heavier loads and when unloaded the engine may not reach operating temp and that can cause damage as well, I would rather repair the problem. I bought my truck used and I do not know how it was speced. I may just have to talk to a dealer and see how it was speced, problem with that most dealers will not help with that.

 

Yeah, when I search parts the one ton comes up as a 3 row but thease are not dodge sites just web parts pages.

 

Well I think I may have this issue figuered. After the truck sitting all winter I decided to study the overheat threads, and with camping/quading season around the corner I had better fix this. I went back to the basics, removed the t-stat and hung it in a pot of water and brought it up to temp and the 180 stat was fully open at 190. So in went a new stat and noticed right away the temp gauge was 10 degrees cooler. I also put in a new fan clutch after the stat because I figured 350,000 km is enough mileage on it.

So in two weeks we will load up and test it out.

 

What brand stat was it you installed??