2012 Grand Caravan Heating Question/Issue? Science/mechanical lesson etc.

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2 months 2 weeks ago - 2 months 2 weeks ago #201782 by VaryJ
Hello, so if I could have some one help explain this to me I'd really appreciate it.

So my 2012 Grand Caravan's 3.6 hasn't seemed to get very warm this winter. I mean it has been a cold winter granted. So I thought maybe the thermostat I put in, in the summer was stuck open, so I replaced that yesterday. I did a flush in the summer with Motomaster instead of the OE mopar coolant, would that have anything to do with this? Here's the results from my test I did this morning. I'm using a 203F thermostat, like the OE and like it was when I changed it in the summer. I changed in the summer as a preventative maintenance thing while I was doing a flush anyways.

So this morning on a 16km/10mi loop with 3 stops going 105kph/65mph at -22c/-4f ambient temp I went from cold to 174-184f once I hit "operating temperature", which I thought to be by the time I hit about 1/2 way in my loop.

Got home, parked in the garage (left door open) ambient temp -16c. Left it running for 10 minutes got up to 194f.

Left home for a 10km loop with 1 stop. Accelerated up to 105/65, this time the engine temp getting as high 199f before settling down to 183f. Stopped for 3 minutes. And drove back. This time going from 195 (after warming up from stopping for 3 minutes) to a lowest temp of 179.

Never broke 203. Fan never kicked on. Upper rad hose feels like water is "moving" either due to the thermostat being open (it shouldn't be right, it never broke 203, are they that accurate or are engine temp and actual coolant temp different) or is that just from the water boiling? But isn't boiling for water 212? So that doesn't make sense. Or is that from the water pump, I'm assuming that's always pumping regardless if the thermostat is open or not. Upper rad hose feels hot, felt colder when I pulled over and touched it after 5km of highway driving at -19 (warmed up a whole 2 degrees from the first loop).

Waiting in garage another 10 minutes. Now 197.

I'm assuming the cold air rushing past the rad even without water flow will cool the coolant to a degree and will act as a really good air cool for the engine + much colder intake air temperature, making for a cold combustion.

So there's all the babble. Here's all the questions:

1) Is my thermostat stuck open? (this is my 2nd one I put one, I'm pretty convinced now the one I put in the summer was fine)
2) What is the "movement" I'm feeling in that upper rad hose? (esp. if the thermostat is not suppose to be open)
3) Is this normal operating temperatures for winter conditions (of course winter temperatures vary more than summer temperatures do around here [Southern Alberta])?
4) Would a piece of cardboard or plastic crazy carpet sled (waterproof haha) help increase my engine temperature during the winter?
5) Why does the engine seem to cool down when I'm accelerating, even if momentarily?
6) Does letting it get to a highest operating temp, then driving help keep it warmer than just going from coldest to highway temp, as you can from the numbers I got? Or rather is this good practice to do that?
7) Does my motomaster (economy) brand of coolant I replaced my mopar stuff with, make any difference in this case?
8 ) Monitored engine temperature - does the reflect coolant temperature in the engine near or around the thermostat or is a measurement of the temperature of the block?

Thank you so much!!
Last edit: 2 months 2 weeks ago by VaryJ.

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2 months 2 weeks ago - 2 months 2 weeks ago #201784 by VaryJ
Last edit: 2 months 2 weeks ago by VaryJ.

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  • nightflyr
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2 months 2 weeks ago #201785 by nightflyr
1) Is my thermostat stuck open? (this is my 2nd one I put one, I'm pretty convinced now the one I put in the summer was fine)
To begin with a thermostat, though stated says 203 degrees may actually be 10% + / - so it could be opening from around 182 to 223
2) What is the "movement" I'm feeling in that upper rad hose? (esp. if the thermostat is not suppose to be open)
Keep in mind there is still circulation happening with in the engine block and heater core.
3) Is this normal operating temperatures for winter conditions (of course winter temperatures vary more than summer temperatures do around here [Southern Alberta])?
It could well be... I'm sure you've seen semi's during the winter (extreme cold ) with radiator covers partial closed while on the road.
Reason is to allow more heat build up.

4) Would a piece of cardboard or plastic crazy carpet sled (waterproof haha) help increase my engine temperature during the winter?
It should but be careful, if there is a raise in air temps you could over heat
5) Why does the engine seem to cool down when I'm accelerating, even if momentarily?
In extreme cold temps and accelerating, even if momentarily your now dealing with wind chill factors
6) Does letting it get to a highest operating temp, then driving help keep it warmer than just going from coldest to highway temp, as you can from the numbers I got? Or rather is this good practice to do that?
Basically asking if warming up the engine will help... that is an internet argument that is very old.
In your case dealing with very low outside temps.
It comes down to this...
If you warm the engine, it will cool down
If you take off on a cool engine it will take longer to warm up.
Choose your poison.
7) Does my motomaster (economy) brand of coolant I replaced my mopar stuff with, make any difference in this case?
If it is certified coolant I wouldn't see any issue, but I do not know that specific brand or if it is compatible.
8 ) Monitored engine temperature - does the reflect coolant temperature in the engine near or around the thermostat or is a measurement of the temperature of the block?
My guess is that it is looking at the block, but that depends where exactly the sensor is located.
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2 months 2 weeks ago #201786 by VaryJ
Knowing that there is a 10% variance in the actual opening temperature of the thermostat, helps me understand this a lot better. I am aware that there is a risk in putting something in the grille, it'd have to be sometime you could take in and out easily for sure, and only for highway use in -20c or colder. Something to think about for me I guess.

The coolant used is certified.

Okay. Thank you so much for those response. I'll keep monitoring my temp periodically and see what happens when this hell-hole warms up a bit.

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