# 2014 2500 6.4l fluctuating engine temperature ???



## scottL (Dec 7, 2002)

SO....2014 2500 6.4L....I noticed a few months ago the temp gauge would drop low and then come back up. It would do it every once in a while but I didn't really focus on it. After a long drive it kept getting warm and cool inside the compartment So then I paid attention.

Now I'm looking at the digital read out and noticed the engine temp would rise to 212, then drop to a lower temp and then rise again. How low.... at faster speeds with more cooler air down to 180, lower speed and less air only to 197. Does it all the time now.

This never happened when the truck was new and I do have the dealer flush the system every other year. No apparent leaks. No codes.

Thoughts???


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## EWSplow (Dec 4, 2012)

With, or without a plow on, or doesn't it matter?


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## ZL1 (Oct 29, 2019)

Assuming no air in the system, the most likely cause is the thermostat.


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## Kinport (Jan 9, 2020)

ZL1 said:


> Assuming no air in the system, the most likely cause is the thermostat.


X2


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## Mark Oomkes (Dec 10, 2000)

scottL said:


> This never happened when the truck was new and I do have the dealer flush the system every other year.


Do they change the thermostat with the flush? They should.


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## scottL (Dec 7, 2002)

Same issue with plow off. The thermostat is $120-$165 dealer being cheapest so they don't change this normally.

Right now dealer is telling no codes == no problem. Hasn't over heated so no problemo. This t-stat has some extra magnet feature but I challenged them to explain to me how the physical device code ever give a code when only the magnet could when at total failure.

O that went over well.... Truck is still in shop. But, I'm agreeing I think the thing failed internally.


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## EWSplow (Dec 4, 2012)

scottL said:


> Same issue with plow off. The thermostat is $120-$165 dealer being cheapest so they don't change this normally.
> 
> Right now dealer is telling no codes == no problem. Hasn't over heated so no problemo. This t-stat has some extra magnet feature but I challenged them to explain to me how the physical device code ever give a code when only the magnet could when at total failure.
> 
> O that went over well.... Truck is still in shop. But, I'm agreeing I think the thing failed internally.


Could have been just a glitch. 
My older Silverado did it once about 2 years ago. 
Tranny temp went up and down one day. Not to the point of overheating, but temp was a little concerning. It hasn't done it since.


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## FredG (Oct 15, 2012)

EWSplow said:


> Could have been just a glitch.
> My older Silverado did it once about 2 years ago.
> Tranny temp went up and down one day. Not to the point of overheating, but temp was a little concerning. It hasn't done it since.


 Ditto, I have had this happen.


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## scottL (Dec 7, 2002)

Not thinking it's a glitch. Although I previously owned several chevy's and do understand the concept.

Dealer said because there are no codes, and the temp kept in range ( 180-212 ) there was no problem. I asked them to show me one other vehicle on their lot that does this .... silence.

From what I've been reading it probably is the t-stat going out. Looking at the device it's a full housing with a dedicate electrical plug in. They call it an electronic t-stat but it looks like a normal t-stat with a magnet and is only sold as a unit - $120-$160.

Bottom line unless I get a code then there is no warranty. I'm guessing it will only code when she over heats ..... ugh.


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## srl28 (Jan 2, 2006)

For what it's worth- I had a problem with a 6.4 of ours heating up, eventually to the point of overheating after some time. Long story short it wound up being the EGR Coooler ( yes a gas engine with an EGR cooler). It was plugged up badly with a thick goop of coolant and whatever else that prevented everything from flowing properly and doing it's job. I had already replaced the thermostat too prior to us finding out more about this egr cooler. Not saying thats exactly what your problem is but just figured I would mention it in case this continues for you.


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## scottL (Dec 7, 2002)

Update; I had the cooling system flushed and a new thermostat ( which is the housing and unit ) changed out. Drove long distance and short .... Now my temperature stays closer to range of 212. So, it will still swag but not nearly as drastic or low and my gas mileage went up I suspect because when the engine registered cool it probably thought to give it more gas. Seems better.

Now to figure out why my AC compressor cycles on/off every few seconds when it shouldn't......


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## dieselss (Jan 3, 2008)

scottL said:


> Now to figure out why my AC compressor cycles on/off every few seconds when it shouldn't......


Could be clutch going bad, tjs did a little right up on his, added a shim I think?

But that constant cycle time means the magnet clutch cant pull in and hold the plate cause it's to far away.


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## NYH1 (Jan 10, 2009)

My '15 does the same thing. It's done it from day one (I'm the original owner). The heat temp in the passenger compartment doesn't change on mine though.

NYH1.


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