This is a cry for help to see if anyone else has had this issue before
My truck is:
2003 Chevy 2500HD Crew Cab 4x4
6.6 Duramax
Allison Transmission

heres the problem, I just had a motor put in this truck , I got the motor from a reputable company that deals with gm and they buy their old stock and other stuff but anyways its a duramax LB7 with less than 5000 miles. I just got it back thursday amd since then every time I go up a grade, incline or any load strain it wants to heat up. Never on flat land even going 90 miles an hour it stays on 205
but when I go up a hill of a decent stretch it jumps up a quick 10-20 degrees then after I crest the top and go about a half to 1 mile its back to the norm of 205 again
any and all help would be greatly appreciated
thanks

need more info. what caused the other motor to blow up? did they pressure check the system after the installation. new radiator or stock dirty one from before the motor install? did they put a new radiator cap? did they burp the system ( no air pockets) does it have a new thermostat? what about temp sending unit is it the correct one for that year? is it the original water pump? install a mechanical gauge to check the accuracy of the electronic before getting too worked up. has the new motor broken in, what thickness oil is being run........................... any coolant leaks or seepage?

need more info. what caused the other motor to blow up? did they pressure check the system after the installation. new radiator or stock dirty one from before the motor install? did they put a new radiator cap? did they burp the system ( no air pockets) does it have a new thermostat? what about temp sending unit is it the correct one for that year? is it the original water pump? install a mechanical gauge to check the accuracy of the electronic before getting too worked up. has the new motor broken in, what thickness oil is being run........................... any coolant leaks or seepage?


other motor didn't blow but couldn't be rebuilt because the heads were corroded from previous owners poor cooling system maint. new to me motor has less than 5000 miles on it but it's not a crate motor coolant and all hoses checked and all good there no leaks at all. Not a new radiator due to a new one being 900 bucks at the dealer. System seems to have no air in it as far as I can tell by running it open for a while and no additional fluid needed. Took it to the dealer today and hooked it to the machine and the gauge is within 2 degrees and mine is mechanical I believe its a dial not digital.
But like I said it only does this under load, going up hills or such does fine otherwise. Air blows cold as well
The tech said it could be the clutch on the fan going out but its hard for me to believe that this stuff was not overheating on my other engine but on this one he says that I may need a new radiator or fan clutch
why would it overheat on this motor and not on the other one
My other motor was bad but never overheated until it really lost it and crapped out plumming white smoke that smelled like coolant. Happened towing my 75 scout home. But I knew it was coming got screwed at different dealer by doing a head gasket job that should never have been done. But anyone please lemme hear your thoughts

Sounds like you covered all the bases. How hot did the engine compartment get when you lost the engine? Does the fan clutch look like it got so hot it leaked? I am not sure if your fan clutch is thermostatic or fluid filled (silicone type) but that may be worth a look. Also if you had poor cooling system maintanance by the PO maybe some crap came loose and is stuck in the radiator obstructing flow. Did you have the radiator cleaned before installing the new engine by a radiator shop? Form what it sounds like these would be the 2 places I would really concentrate on. One last thing, check between your AC condesor and the front of the radiator and make sure you don't have a bunch of leaves or debris in there. I once found a shitload of animal fur between the condensor and radiator. Cleaned it all out and the overheating problem went away.

This is a cry for help to see if anyone else has had this issue before
My truck is:
2003 Chevy 2500HD Crew Cab 4x4
6.6 Duramax
Allison Transmission

heres the problem, I just had a motor put in this truck , I got the motor from a reputable company that deals with gm and they buy their old stock and other stuff but anyways its a duramax LB7 with less than 5000 miles. I just got it back thursday amd since then every time I go up a grade, incline or any load strain it wants to heat up. Never on flat land even going 90 miles an hour it stays on 205
but when I go up a hill of a decent stretch it jumps up a quick 10-20 degrees then after I crest the top and go about a half to 1 mile its back to the norm of 205 again
any and all help would be greatly appreciated
thanks

i would replace both thermostats before i did anything else. yes there is two.

edit: to be more specific one opens @188'F and the other@206"F

I am gonna see if they can test the flow of the cooling system to see if it is obstructed and I am also gonna check on the fan clutch
The fan is a lot cheaper place to start than the radiator on replacing things so I may do it first
Thanks for all the input and all is appreciated

If the old motor was beyond repair due to poor cooling system maintenance (:shaking:), then I would definitely have the radiator flushed and have the tubes rodded out.
it is normal for engine temp to rise some pulling a grade.

I would check the radiator and thermostats first

^^^ Ditto.

The statement of poor cooling system maint. by the PO followed by the reuse of the old rad. rings a bell. I understand not replacing due to $$ ....BUT did they flush/rod it out as mentioned? With the poor maint. it may be partially clogged and not functioning as efficiently as it should. And a 10-20 degree jump really doesn't sound like much under load.

If the radiator flush doesn't do it, my guess is that the 2nd thermostat is sticking a bit. If everything checks out ok, it could just be that the new motor runs a little hotter when making power.

thanks everyone for the help

This is a cry for help to see if anyone else has had this issue before
My truck is:
2003 Chevy 2500HD Crew Cab 4x4
6.6 Duramax
Allison Transmission

heres the problem, I just had a motor put in this truck , I got the motor from a reputable company that deals with gm and they buy their old stock and other stuff but anyways its a duramax LB7 with less than 5000 miles. I just got it back thursday amd since then every time I go up a grade, incline or any load strain it wants to heat up. Never on flat land even going 90 miles an hour it stays on 205
but when I go up a hill of a decent stretch it jumps up a quick 10-20 degrees then after I crest the top and go about a half to 1 mile its back to the mr gasket thermostat (http://www.thepartsbin.com/brands/mr_gasket/mr_gasket_thermostat.html) norm of 205 again
any and all help would be greatly appreciated
thanks

Hi there man. Does your 2nd thermostat really was really sticking a bit? My friend is trying to revive his own motor right now.