ive noticed something new with my truck in the last few weeks. if i leave the truck parked for a couple days, when i drive it and it warms up, the monitor says around 223-228 degrees before the thermostat opens up. if i drive it every day, it will only run up to around 215 degrees, and both ways, it will level off around 204 and stay that way if i keep it at 60. if i get on the highway and get up to 70 mph, it runs around 210-212 degrees.

my last 2 trucks both stuck at 180ish, maybe a little warmer when towing. im wondering if there is just something wrong with the thermostat? or if there is something else that could be going wrong. every one that i know that has a CTD says their trucks run around 180 all the time with no problems, even towing. all the fluids are up to snuff in my truck, and id like to start with the cheapest part first. im guessing these trucks come with a 180 thermostat stock? and im wondering if maybe the previous owner put a hotter one in it... and help would be much appreciated. TIA

 

Mine normally runs between 195 and 202 according to the Bully Dog! Maybe a tad bit higher on a long uphill but it stabilizes.

 

Yea, 195 to 203 for mine unless towing the fiver and then its 200 to 204 and a little more when climbing hills that are long. Temps are at 65-70 mph.

Dave

 

so should i worry about this to much? these temps are with edge on mileage setting. i havent towed my 5er yet, so i would like to get it set before i do. i just dont understand why it gets so hot, then backs down.

should i try getting a 180 thermostat to see if anything changes?

 

Do you have a pyro? What do your EGTs look like?

Sounds a little high unless you were in summer heat and towing...

 

I would bet your thermostat is sticking. May need to be changed.

Check the Fan connection under the truck on the drivers side just behind the radiator. Follow the wire down from the fan clutch and make sure the connector is tight.

Mine was loose and the fan would not work. I put a small tie wrap around it to keep it connected. If you have a lot of light oil on the connector you might be loosing fluid from the coupling on the fan clutch.

Also I don't see any higher than normal temps when the Juice is set on the tow mode or mileage position.

Dave

 

Thermostat is neither expensive, nor difficult to change. If I had any doubt, I'd just stick a new one in.

If this is the 05 in your signature, and the coolant hasn't been changed, it would be good to pick up some HOAT (zerex G-05) and some distilled water and knock that out, too.

 

EGTs are around 600ish cruising pre turbo

i believe the coolant was serviced around 100k, and its got 138k on it now. i think im gonna start with a new thermostat. i heard somewhere that thermostats other than ones from a dealer wont stand up the to the vibration. any truth to that? i would much rather pay $20 for one from napa than $65 from the dealer.
Jeff-
where can i find that HOAT? is that something that most parts stores carry? might not be a bad idea to start with fresh stuff i guess right?

Dave-
i will also check that plug.

 

I'd check your local Cummins parts house for a thermostat.

HOAT is hybrid organic coolant. As I understand it, it combines longer life than traditional ethylene glycol coolant with better protection when new.

Zerex says on their web page that their G-05 HOAT is used by Dodge as factory fill, but died red. Zerex comes gold colored.

You can find it at most auto parts places.

As a side note, running a way too high antifreeze concentration can cause higher operating temps...

 

ill have to call around for the thermostat. ive always mixed 50/50 antifreeze mix. that sound good for these motors?

 

50 or 60% I would think would be fine. Some shop put in what had to be almost straight antifreeze in my dad's 300 Ford 6 years ago. It took us a while to figure out why it would overheat...

 

Might also be a good time to clean the radiator, intercooler etc by using the garden hose to squirt water opposite of the air flow, meaning from the back to the front.

Attached are the coolant change instructions from the owner's manual for my 06.

 

well decided to take advantage of a rainy day yesterday and get some stuff done to prep truck and trailer for the first heavy voyage with the new rig.

first of all, just like to say thanks to you folks who helped me out! picked up a new thermostat for the truck and checked the fan clutch plug. got everything done, mad sure lights and brakes where working on the trailer, and headed to NE PA to pick up a tractor for a buddy today. trailer is 6K empty, and the tractor weight around 7K. even with the hills of souther tier NY, the truck never rose over 197 degrees! everything is working the way it should be.

but on another note, my egts were running around 800 cruising on flat land, 900ish on mild hills, and around 1200 and pretty steady on the good long draws, but would hit around 1300 is i had to get into it for a short time. is this right around where they should be for these new model's? the numbers were with the juice on tow setting.

 

Those EGT's are fine. The 03 I had would hit around those numbers, and the 06 I have now will run a bit higher- both totally stock.

Glad you got the temp situation corrected.