6.4 Hemi Overheated

[FlatbedHemi]

Was sitting in the trailer line waiting to unload at our local fair and I noticed the A/C wasn't cooling as well as it should. I figured it was because we were idling in a parking lot in 96 degree heat, so I turned on the recirculate and kept doing what I was doing. A few minutes later it dinged, popped a light, and said engine too hot on the screen. I went through the SOP for overheating; A/C off, heater on high, pop hood. We made it through the line and got loaded without getting the temps over 235-240 again, but I knew there was an issue somewhere. Long story short, I think I narrowed it to the fan clutch because it cools when parked and revved or in motion. Its just sitting still at idle that it gets hot. So, i ordered a new fan clutch.

Now Im wondering if I need to go ahead and change the coolant and do a flush or something. The truck has 131K miles and never had any coolant maintenance done. Is there a specific procedure for performing a flush on these trucks?

What about the T-stat? Is it likely that it likely that the minute or so that the truck hit 255 that it ruined the t-stat? I have noticed that when at speed and unloaded, temps run between 195-205. Honestly, I never paid much attention to the temp other than just where the needle is, so I dont really remember what temp it normally ran at.

 

[mtofell]

IIRC, the factory recommended flush is 150K so probably a good idea.... although, I doubt that's the issue. I think you're on the right track with the fan clutch and maybe the thermostat. Over the years I don't recall reading too many problems with the 6.4 Hemi overheating. My thermostat went out once but it was opening too soon and I was getting an error message about the engine not reaching temp quick enough.

 

[Choupique]

Our work trucks (ram 6.4's) will sometimes overheat in the dead of summer with the AC blasting and the sun beating down. RPMs is the short term answer. Get the engine up to about 1800 and the temps will nose dive.

Nothings wrong with those trucks other than the cooling system is just inadequate to handle all that heat.

 

[FlatbedHemi]

This may be a stupid question, but does the 6.4 have an electric fan under the machanical fan shroud? It doesnt make much sense to me that it would, but I was watching a couple of videos on changing the fan clutch (to make sure there werent any hidden boogers to work around I wasnt aware of) and I saw what looked like an electric fan mounted between the radiator and the mechanical fan. I havent torn into mine, so I thought I would ask.

 

[buckeyexx]

This may be a stupid question, but does the 6.4 have an electric fan under the machanical fan shroud? It doesnt make much sense to me that it would, but I was watching a couple of videos on changing the fan clutch (to make sure there werent any hidden boogers to work around I wasnt aware of) and I saw what looked like an electric fan mounted between the radiator and the mechanical fan. I havent torn into mine, so I thought I would ask.

Yes it does have both a mechanical and electric fan. Just had both of mine out when changed my radiator and water pump. If you have access to an air hammer it will make breaking loose the fan clutch a breeze.

 

[Travelin Ram]

Have you checked the electric fan? I’d expect that’s doing most of the cooling at idle.

 

[2003F350]

Have you checked the electric fan? I’d expect that’s doing most of the cooling at idle.

This. I never had an issue with mine, but then mine didn't sit and idle much, I was usually moving. But on the rare occasions when I was idling, I could hear the electric fan kick on and off and never saw high temps.

 

[FlatbedHemi]

Finally got around to this, and using the Alpha OBD program I was able to diagnose my fan was in fact bad. Since I had already ordered the mechanical fan clutch before I realized there was an electric fan, I opted to go ahead and replace it too rather than return it. Everything was incredibly smooth and easy to replace, which was surprising. Now that everything is replaced, the weather will be in the mid to low 70s for the foreseeable future. Guess I shoulda gotten to it sooner if that was all it took to drive the 105+ degree days away.