Engine overheating when driving?

2018 RAM 3500

70,000 MILES • 6.7L • 6 CYL • TURBO • 4WD • AUTOMATIC

GCT1212

MEMBER
2 POSTS
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The engine is overheating when speeding up sits fine at idle and when cruise is set and on flat terrain the temperature holds steady but is still running hot. Had thermostat replaced in January and again in May. Also, in may had radiator flushed out and new coolant put in. Truck has been fine since then but about a week ago it started overheating again. Not sure what to do.

Jul 15, 2022 at 3:52 PM

STRAILER

CERTIFIED EXPERT
53,855 POSTS

When the engine is running hot or overheating can you hear the cutch fan kick in? If not the first thing was needed to do is check fuse # 78 10-amp int he under hood fuse panel, this fuse controls the radiator electronic clutch fan, if that's okay the truck may need the electro fan clutch replaced, here are the instructions in the diagrams below plus a generic guide on what to look for when the truck is overheating.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

and

https://www.2carpros.com/articles/engine-overheating-or-running-hot

I have also included the cooling fan wiring diagrams so you can see how the system works. Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

Images (Click to enlarge)

Jul 16, 2022 at 6:08 PM

GCT1212

MEMBER
2 POSTS

Yes, the fan clutch kicks in and is working properly. Also not losing any fluid. No leaks in the system anywhere.

Jul 16, 2022 at 7:03 PM

STRAILER

CERTIFIED EXPERT
53,855 POSTS

That's good, I would use a garden hose and using the pressure setting and reverse hose out the radiator fins (fan side) and clean the front and make sure there is no hair/bugs/leaves etc. When you had the thermostat replaced was it an OEM unit?

Jul 17, 2022 at 10:53 AM