Cooling issues (2012 RAM 1500 V8 Hemi)

[Hoopdawg]

2012 RAM 1500 Big Horn Hemi V8
Anyone have any ideas on why my temperature keeps rising? I changed out the computer module (ECM) that starts the fan which was apparently a problem with my model Ram. Was doing great until yesterday when the high temp coolant light came on while sittings till at idle. It did not throw a code but the temp got up to around 247 degrees F. It seems like the fan is coming on but not "early enough". The temperature eventually comes down after driving a ways, but it seems it shouldn't get hot sitting still like that. Don't know whether I may have a water pump/radiator issue either, as i have not had a chance to investigate that. Can anyone speak to these issues and give some advice?

 

[Ken226]

2012 RAM 1500 Big Horn Hemi V8
Anyone have any ideas on why my temperature keeps rising? I changed out the computer module (ECM) that starts the fan which was apparently a problem with my model Ram. Was doing great until yesterday when the high temp coolant light came on while sittings till at idle. It did not throw a code but the temp got up to around 247 degrees F. It seems like the fan is coming on but not "early enough". The temperature eventually comes down after driving a ways, but it seems it shouldn't get hot sitting still like that. Don't know whether I may have a water pump/radiator issue either, as i have not had a chance to investigate that. Can anyone speak to these issues and give some advice?

If I understand you correctly, it gets hot while idling but will cool down when you are driving at speed?


Your 2012 has a hydraulic clutch fan that does the heavy lifting when the truck is at low speeds or idling. The little electric fan doesn't have the huevos to do it all by itself.

With the engine off, see how much resistance to turning you feel when you try to rotate the fan?

If/when you replace it, I would recommend getting a MOPAR OEM fan from somewhere like Mopar Parts Giant, or similar. Aftermarket units have a bad reputation.


check out this video.

How to diagnose a bad fan clutch scenario.

A micro lesson on how to diagnose a freewheeling fan clutch that is causing the A/C to not blow cold air in stop and go traffic.

youtu.be

I believe you'll be needing part# 55056840AC

55056840AC - Mopar Parts Giant

www.moparpartsgiant.com

Aftermarket ones cost about 1/4 as much, but i don't think i've ever heard of one actually working right. You'd probably be better off buying a used one on ebay than buying an aftermarket one.

 

[Burla]

You have not had a chance to investigate hardly anything but you want a bunch more to look at? What I can say is you have a great year for ram truck, worth taking care of, make time to investigate bud, period end of story. If you mess around with hot temps even with a gas truck you can warp your heads, so know if you keep running at 250f it is very likely you will damage heads.

We don't have any info on your symptoms, we would need a ton more to through guesses at you. Fan is a good start if just hot at idle. But if it gets hot soon as you hit idle like a stop sign, could be other issue thermo/water pump whatever. Can we assume you checked fluid level at over flow tank?

 

[Burla]

Normally you can idle down temps to mitigate temps and damage, but you cant even do that. Until you figure it out you can get a water wetter and see if that keeps you away from 250f until you figure what is going on. It is getting hot because there is no wind like there is when you are in motion, so it makes sense it only gets hot at idle when something is wrong.