Overheating on the highway with normal EGT's
 

Well, I'm not towing anything, the air temp is hot, but not even 90*. Turn onto the highway after being stuck in traffic. Turn on the A/C, look down and sure enough I'm at about 200-210*, hot for what the truck normally runs at 190*. Now, its idled rough for a while, I got new injectors today as a matter of fact. Everything looks and runs like normal, but the temp is high. I pulled off at one rest stop and let it cool down a little bit, popped the rad cap and it puked a little fluid (greenish brown, I know I gotta change it but thats clearly not the problem alone). I filled the reserve bottle with water, all I had at the time, and all the way home, 2.5 hours, it ran just over 190, occasionally dipping down to 190, other times hitting 200 or so.

Here's my plan of attack:
Flush the coolant and throw whatever cleaner I can find in there.
Power wash the radiator in the truck, with the intercooler and everything still in (bad idea?)
Replace the thermostat (it was replaced about a year ago)
Do whatever you fella's recommend if it seems logical...

So what ideas have ya got? And do you all agree that its a cooling system problem, not an engine problem?

What you listed above should solve your problems unless your HG is leaking.

I've blown HG before, with 12V albeit, but this doesn't seem to be a HG problem. The rad was under pressure, but only because it was hot when I opened it (don't try that at home kiddies :w2:). There wasn't any coolant blown into or out of the reserve bottle.

you would have better luck with the cleaning if you pulled the radiator i think:humm:

yeah but thats such a PITA, I realllllyyyyyy don't want to have to do that.

Anyone know of a good radiator cleaner? Inside I'm talking, not the outside. A pressure washer should do that.

There is a good chance the oil puke bottle on the front of the engine has finally plugged up enough of the radiator and its not getting good airflow though it. The only way to throughly clean it is to remove the radiator from the truck and powerwash it. Taking the radiator out really isn't that big of a deal, takes all of 20 minutes.

Last time I did it it took a bit longer than that, but again, it was a 12V. I know how to clean the outside of the radiator, I want to clean all the shit out of the inside (the coolant passages and whatnot).

20 minutes at least. Mine was caked all the way through. buy a new lower radiator hose while you are at it, make it a planned purchase instead of an emergency as sometimes they get wrecked when you take them off and you will have to try to save all your coolant.

use powder Soap to flush the system. also only use a cummins thermostat.
Re fill with NEW coolant

make sure the radiator fins are not clogged with bugs or if you have a piece on screen in front of the radiator that can do it too. Also some after market grills can restrict airflow.
Ed