Running Hot on the Highway

Any new updates? Still kind of curious...

I had it out on a high speed road and cruised at 60 mph but only for 3 or 4 mintues. It was about 65 degrees out and the temp gauge did not budge.

I bought an infrared thermometer and pointed it around at various components when I got home and nothing is hot. It was only 175 degrees on the intake under the thermostat, top hose maybe 160, bottom hose 140 etc.

Back in the winter when it was real cold out the temp would go right up as soon as I got on the highway so I am definitely making progress. But I need to get it out on the highway on a hotter day and a longer amount of time to really know if it is fixed or not. So when the weather gets hot again I'll get it out on the highway for a long stretch, pull it over, and get some temperature readings with the infrared thermometer.

Sounds like you fixed the problem.

I have been quietly following this thread as I WAS having the same situation with my 66.I have a fresh engine {stroked sm. block} four speed ,with factory a/c. With a 180 t-stat,170-180 in town. On the highway,200-205 of course with the a/c on. I have a three core rad freshly done, mopar performance viscous fan,and fan shroud. the problem solver was the mr. gasket high flow t-stat, 180-185 all the time :cheers::cheers:

This might sound elementry, but if your lower radiator hose does not have
the coiled wire inside, it will colapse at freeway rpm and restrict the coolant
flow. Around town no problem.

I would say that if you're making progress, it may have been that the old thermostat was defective.......or at least restrictive junk. That thing should've been WIDE open before 180.....yet you mentioned the top hose wasn't that hot. I guess the true test will be when the OAT is 85 degrees or higher.

All 3 of my Darts all run at 185 on back roads and 200+ on highway, 273, 318, 225 is only 1 with new radiator. All bone stock. I thought this was normal?