Temp gauge redlines while towing

[CelticNomad]

Hello all. I wanted to reach out for input before my visit to the dealership. Information is a good thing.

It's occurred 4X now. Pulling with my 6.4L and 4:10 ratio. Travel trailer is 8k in weight, far below the trucks limits. I'm on the ramp getting onto highway and up to speed when temp gauge goes right over triggering "hot engine" warning in the message center. All this occurs in a quarter mile, even less. Literally, gauge goes from normal at beginning of ramp to "hot engine" before I can get on the highway. Of course I pull over where gauge immediatly returns to normal and warning disappears and I go on my merry way.

This only happens when getting on the highway for the first time in the day. Off and on several times later in the same day for pit stops will not replicate that morning. I will add that the 4x this has occurred is out of the last 5x getting on a highway with the trailer so it's a recent development. No indication from under the hood that there is a problem.
It has never occurred without the RV.

As simple as a thermostat? Water pump beginning to fail under high demand?

Thanks in advance.

 

[motorhead426]

Can you provide us with more specifics of your truck? Year? Mileage? how many miles on the coolant, etc?

 

[CelticNomad]

Obviously I'm a new guy on here. Providing the basics would be nice. My truck is a 2024 2500 Tradesman ,with the hemi, approximately 28k on the mileage and the coolant is the original stuff.

 

[Poolmonkey]

How long does it take to supposedly cool off…impossibly fast?

 

[CelticNomad]

"Impossibly fast" is a good choice of words. The inverse being how it goes from normal to hot engine bells going off in < a quarter mile. As I stated, it only happens with towing and calling for power on the entrance/acceleration ramp of a highway to get to speed.

 

[Poolmonkey]

"Impossibly fast" is a good choice of words. The inverse being how it goes from normal to hot engine bells going off in < a quarter mile. As I stated, it only happens with towing and calling for power on the entrance/acceleration ramp of a highway to get to speed.

So it isn’t really getting hot, the engine that is. Maybe the sensor is…
I had a truck with a bent valve spring that would heat the cylinder head temp sensor crazy fast, it indicated engine temp, when revving and then cool it within seconds when not. The problem would manifest only when pulling a grade while towing, the only situation that would prolong any high RPM and heavy throttle. Would not do it revving sans trailer and grade with a low gear selected no matter the duration.