I've got a 4.7 Quad that I pull a 8x16 enclosed trailer (about 5000 lbs). It has a 180 thermostat and runs cool when not pulling trailer. It doesn't get hot when pulling the trailer unless the A/C is on. The gauge is about a 1/8inch over the half way mark with the A/C on only. If I cut the A/C off it goes to half way on gauge. I don't like running that high with the aluminum head problems. Anybody elsehave this problem? Is this anything to worry about?

 

If it is in the normal range, don't worry about it. It's normal to run a bit hotter when towing and running the a/c, etc. It's probably only running about 220 which is ok.