LB7: Engine Won't warm up

[KC-RUNNER]

I have a 2003 2500HD Duramax/Ally. Has mild BANKS tuner and cold air induction. Even with a portion of the radiator blocked off truck won't warm up. I installed a mechanical gauge to insure the electronic gauge was correct(it was).
I just replaced the thermostats. The rear one has a reputation for sticking. It still won't warm up will only get to about 180 deg F. Lastfall it would get to about 210 deg F.
I have had this issue before. It kind fixed itself before.
I would like to get engine temps up to over 200 deg as I think fuel mileage is better.
I am wondering if there is a fuel delivery problem(to much fuel) which may be cooling the engine.
Truck has 213,000 miles. Injectors replaced at 196,000 miles. I dont think there is a bad injector. Oil is bright with no diesel smell.
I hope one of you guys has a brilliant idea.

[KC-RUNNER]

I went to lunch today. Going to lunch spot about 4 mile away the truck ran about 180 deg F. On the way back it ran about 180 deg F for 2 miles. Then all of a sudden the temp gauge goes to almost 210 deg F.
It was about 45 degrees F by the truck temperature indicator in the rear view mirror.
I am going to be very interested to see what it does on the way home.

[keremeos1]

could there possibly be an air pocket in the system?

[yurlosin]

ive been having the same problem since i got my truck have since replaced the injectors and the thermostats after that so the coolant has been drained twice so i dont think its air pockets any help is great kinda at a loss here

[BigPower802]

Mine has run at 180 all winter unless I get after it then the temp will climb up to 210. But it will drop back down if i ease back up on it.

[TOTHEMAX!]

What do you mean by a portion of the radiator is blocked off?

180 is not a bad temperature in the winter time. Like previously stated these trucks will not warm up to 210 unless you are pulling or in the throttle for a long period of time.

[jon5212]

As others have said in the winter it won't hit 210 unless towing or heavy on the throttle. You possibly could have gotten bad thermostats.

[5Cent]

I wouldn't complain about 180 at this time of year. What is your location?

I had the strangest thing happen to me this AM on my 18 mile trek to work. About half way down the highway (front winter cover on), doing 70mph, my hot air just stopped! Got freezing cold and the engine temp was buried at cold. I looked to make sure I didn't bump AC on, changed all the settings, and it didn't do anything to help.

About a mile or 2 later, the heat came back, the temp started to rise, and all was good again....go figure.

[kcb37]

I would agree, I don't think I have seen 200 degree's in cold weather. Mild with something over the grill yes, but that's when I take it off.

[u00bse1]

I totally block off my rad with a piece od plexiglass inbetween the CAC and Rad and then remove my fan assembly and run 180 in winter. These items due help warm up time and I do have proper working tstats. The temps you are seeing are normal.