I own a 97 RAM 3500 with the 8.0 V-10 with just over 36000 miles on it. I also have a 20ft trailer that I use this truck for.

On Thursday I finally got the right front axle u-joint replaced. I took the truck for a run, about 10 miles of HWY driving. All seemed well on that run.

On Friday I made about a 50 mile round trip run to Duluth Mn. to recover my sisters broken down car. As I was heading in with the trailer on I noticed that the temp gauge was fluctuating... It would run up to about 210 degree's, then drop back to 190 degree's.

Coming out of Duluth I had to make a run up a pretty steep grade for about 1.5 miles... When I got to the top of the hill the truck was running at about 230 degree's so I pulled off of the road... When I checked the coolant level, it was where it was supposed to be, and the coolant wasn't boiling into the reservoir. When I got back on the road, the temp climbed up to 210 degree's, and stayed there for the rest of the way home.

My initial thought was that the thermostat is going bad That said, I used to have a boss that used to tell me that I tend to "overthink" things... I had a hard time disagreeing with her...

So I can't help but wonder if it might be something else... The sensor, and gauge seem to be working as they should... The gauge went up and down based on the load I was putting on the truck.

That leaves me thinking about the pump, or potential radiator blockage... I'm wondering if there are any quick/easy troubleshooting procedures I can do to make sure that the pump isn't getting weak, or that I have any blockage?

 

Run the engine up to temp, then use of the IR temp guns to look for hot/cold spots on the radiator. That should give you a idea if the radiator is clogging up.....