Help. Ram 1500 with 4.7 engine with 120 k miles suddenly starting to run much warmer per gauge. Have now flushed system and reinstalled 50/50 antifreeze mix. Changed thermostat and upper and lower hoses. Changed temp sending unit - all with no change. Not losing any coolant. Heat gun on radiator and all hoses show temp between 150 and 195 degrees. Fan appears to be spinning at all speeds but who knows running down the highway. Temp has never been a problem and has always stayed a little below halfway on gauge. Now running at 3/4 plus. No codes on engine. Have reset computer. Engine will run old normal temp for a few miles and slowly creep up. Will not cool down at either highway or city speeds. Any ideas would be appreciated. My next thoughts are the fan clutch and water pump. Thanks
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Maybe radiator is starting to get plugged, I know you said you flushed it, but sometimes flushing doesnt get everything out. My next thought would be the fan clutch..... Question, you said that the heat gun shows 150-195 on the radiator and hoses, is that while the gauge is showing 3/4 of the way up?

 

several things, you may want to buy a 180t stat.
its prolly your fan not working at high speed. it should take you about 25 minutes to get the fan off, take some channel locks and a wrench and rip it off, see how loooose it feels, it should feel pretty tight when you try to turn it.... stock fan is around 50-60 bucks... you may look into investing 200-300 in a nice E fan, itll give you better flow at idle and same flow at speed and itll free up around 10-15HP.. another issue you could have and its simple, the rad cap could not be sealing properly thus not keeping pressure on the coolant...

good luck

 

The fan won't be turning at highway speeds except for windmilling. Could be the pump. Is it possible there is air in the system? Have you pressure-tested the system? That is a lot of miles for the original cap and water pump. Most pump failures will show as weepage under the pulley. Unless your new 'stat is sticking (not unheard of), changing it again won't make much difference. Try moving the fan up and down or side to side. If it moves at all, the pump bearings are bad. You could also try removing the 'stat, but you'll get some codes after a while. If it still runs hot then, something's blocked.

 

Thanks for all the replies. The latest - changed out waterpump and fan clutch this week-end. Removed thermostat and replaced with one that I punched the center out of so it now has almost full flow. Reached the point that I didn't believe the factory gauge and installed a secondary temp gauge. Engine is still running hotter than it should. It is 95 degrees outside today and according to the new temp gauge - I am getting as hot a 238 degrees when running down the highway. Truck runs great but I still think it is running way too hot. It will cool down to around 230 degrees running around town now. Absolutely not losing coolant and have no air in system. New gauge sending unit is mounted in place of bleed screw on hose right before return hose into radiator. Hate to pull the radiator but I am running out of ideas. Thanks
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There's something certainly backwards there. Should run cooler on the highway. With my 180 'stat and e-fan, my truck runs at the old "normal" (just under half) in town. On the highway it runs just over 1/4. I'm afraid you're now on the right track -- radiator repair/replace. Tough break!