My '89 Dodge D250 LE 5.9 Cummins L6 is getting quite warm. It is the first time towing a heavy RV trailer. The temp guage is of the sort that has no actual temp number. My question is this: How warm is the second point just below the H at the hottest point on the guage, and is this normal after just tackling a steep hill towing a kinda heavy RV trailer?
This is my first time here and I look forward to picking ALL your brains in the future for upgrading my Cummins to get more torque. All advise will be GREATLY appreciated.

 

Well, being a no name gauge who knows how its calibrated.

Is the temp sender in the pan or in a line?

If the temp went up just after a hard pull up a steep grade I would not worry about it as long is it setled back down to "normal" afterwards. If you plan on towing heavy alot a good gauge and a good cooler might be a good idea. We have site soponsors that can get you great service and deals on both!

oh and...

 

my truck did the same thing but worse, i was not towing anything.
i deduced it to being a bad radiator design. non i/c first gens have top flow radiators with both the inlet and outlet on the same side. so what i did was i swapped in a new intercooled first gen radiator. dodge changed their design to a cross flow style that cools way better than the top flow. i bought the two upper clamp/mount plates from a intercooled truck and fabbed up the lower mounts myself. the only cutting i had to do was to notch the radiator support so the new radiators upper support gussets would slide down. hight wise it barely fits, i had to dent the hood on the inside a little to clear the end tanks, the radiaotor is mounted as low as possible, and i put in a fan clutch from a second gen truck(i cut the threads shorter to bring the fan closer to the motor because it is a extremly tight fit. everything works amazing now and i have had no overheating problems.