Coolant depleted without any visible leaks

I drive a 2019 T680. I need to keep the coolant all the way to the filler neck. Once it reaches the "full cold" mark on the tank, it starts chiming at me like church bells on Sunday morning! Apparently an issue with the coolant sensor location in these Paccar engines.

 

no most trucks in at night

 

I personaly think the full mark and low level chime are way to close.The chime will go off in most of our trucks(and its halfway between the low and full mark when they start it in the morn) till they get to operating temp then goes away

 

I have had my truck dashboard light up like a Christmas tree on more than one occasion, screaming at me to SHUT DOWN NOW.....LOW COOLANT. ENGINE DAMAGE WILL OCCUR!!! Only to pull over when safe to do so, open the hood, and coolant is between full and low. I just fill it til it overflows and it shuts up!!

 

I have no idea if this is true but a few friends have told me that a small amount of coolant is used in the def system

Again. Not sure if it’s true or not just 3rd party information

 

Without researching that statement, my answer would be no. It just doesn't make sense. The cooling system is a closed system. There would not be any way that would make sense.

 

Only coolant used in the DEF system is a heater core to keep the DEF fluid from freezing.

 

That has been my thought also and why I put that I only heard of it but for some reason I’ve had more than one person tell me the same story that it somehow cools the def system

But logically it seems more like a common leak issue rather than a def thing

Maybe that’s we these shops are telling them as they can’t fix their own crap either???

I had a 2019 Peterbilt
Big POS
Now a 2021 and not much better, it is better but not much and I truly believe that Peterbilt has dropped their standards and are no longer the truck they used to be

I have non stop rattles and every few hours it moves from one place to another