Welcome to the forum.**RAM and Diesel Rookie** not sure if this is the right thread for this post; but here is my question/symptoms. I just bought a 2014 RAM 1500 Diesel, and I regularly tow a 4200lb boat (I believe the tow cap of this truck is 9200 lbs). Last week when I was going up a significant grade with the boat attached for the first time, the engine temp increased to the 3/4 mark, the motor did not overheat or have any indicator lights so I kept going.... but I have had multiple other vehicles tow and have never seen the engine temp rise past the mid point? I didn't know if it was the difference between the diesel motor and the gas motors I have had in the past? I also noticed that the engine coolant appears below the suggested mark but there is still coolant in the tank. Is this something to be concerned about or normal for a Ram Diesel? Other info- it is the Laramie edition and it was approximately 110 degrees outside when the engine temp increased.
Over on the first page are the 2 grills to try and stay away from. It appears you have one of those grills. I did, also (Big Horn) and changed it out.
2 things you didn't mention was 1) What did the EVIC say the temp was. and 2) How fast were you going, as speed has a big impact, although less with boats than travel trailers (plus most trailer tires are rated for 65mph).