I recently installed a remanufactured engine from cummins. I noticed that it didn't get as warm as my previous engine and it rapidly lost temperature when slowing or at an idle. Now that it is getting colder, the engine does not heat up at all. I replaced the thermostat and nothing has changed. I will drive it hard for 30 minutes and then feel the oil pan and it is barely warm, and the antifreeze is cool enough that i can stick my finger in the radiator. The upper radiator hose is cool and not pressurized. why will it not warm up. Its about 40 degrees outside.

 

sounds to me like a stuck open thermostat but if you say you replaced it...... that worries me.

is 30 mins normally enough to warm her up? im asking cause it rarley gets down to 40 here and i always warm mine up in the drive first. but sometimes it still takes 10-15 mins to get some heat out of it.

have you tried a high idle set up in the drive way to make heat? this way you should be making heat without air going across the radiator/ block.

does the temp gauge come off "C" at all?

 

our tepmp guages start at 140. my 12v usually will have pop the thermostat after 5 mins of idle and 10 miles of driving in 20-10* wether here

 

believe your t-stat is faulty.

 

Mine is like that too. I've replaced the t-stat
a few times. I run no fan, and cover the rad up and
still get very little heat, either in the cab or in the motor.
I never put the fan back on, just remove the cardboard
in about late june or so. Sorry I'm not any help erik.
But at least you're not alone.

 

Do what the fish says her............just dont run yer A/C when the truck is stopped thats all

also if you tow you will want the fan back on too or remove the cardboard and watch the temps closely

 

mine takes a good bit to warm up about 40 minutes or so when it gets below 50 degrees

 

i have a feeling these motor's are very efficient in cooling. before i switched to electric fans i ran my 12v for almost a week in the texas heat with NO fan. the motor never cracked 180.

 

in 30-40* weather here when the truck is cold, has been sitting for 6-7 hours, i can drive for almost 20 miles before the temp comes above 140. i have even driven home from a friends (25 miles) and when i pulled into the driveway the thermostat opened and i saw the temp gauge drop back to almost 140*

 

check for recalls some of our 2nd gen dodges have a recall specifically for this mine did now it warms up fine