Proper operating coolant temp for a 2010 Ram 1500 5.7

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My2010Ram

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Hi everyone, I have 2010 Ram 1500 quad cab with the 5.7. I bought it last December with 86k miles on it and it’s been great. I’ve noticed in cooler weather my highway driving temp can be as low as 175 degrees and then when I sit long enough it can climb up to 203 (never seen it higher than that). I usually let my truck warm up for 5-10 min in cold weather but if I don’t and pretty much getting going shortly after starting the truck I’ll get a CEL after a few miles that says that my engine operating temp is to low. It seems like even in warm weather the truck takes forever to get up to operating temp. I just bought a new stock thermostat because I’m assuming my temp numbers are so far apart my thermostat has got to be stuck open. My real questions is… should I consider a thermostat to keep the engine cooler like around 185-190? I don’t mind that my engine running a little cooler but I want the temp to stay more regulated and not vary as much as it has been. Also wondering if there will be really any benefit at all to running this engine cooler than what dodge recommends. I don’t pull a whole lot with it and it’s basically just a daily driver.
 

Burla

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You have no issue, just leave it where it is everything is ok. If you feel like it you can up the percentage of coolant to deal with the too cold issue and watch it on the other end. Going to a cooler thermostat would be the completely wrong strategy if you are getting a code that says temp low.
 
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My2010Ram

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You have no issue, just leave it where it is everything is ok. If you feel like it you can up the percentage of coolant to deal with the too cold issue and watch it on the other end. Going to a cooler thermostat would be the completely wrong strategy if you are getting a code that says temp low.
Thanks, good to know it’s okay. I was thinking that the thermostat was stuck open and that’s why it takes a while to get up to temp. As far as the cooler thermostat is concerned I was just wondering if anyone here ran their 5.7 cooler for any other beneficial reasons. I figure even a lower temp thermostat will stay closed until it reaches its specified design temp to open, which is above the temp as to not trigger the CEL. Since I ordered a stock thermostat i might as well change it out because I have no idea if what is in there has ever been changed and I’m guessing not. I’m at 100k now and going to do plugs, belt and pulleys.
 

Burla

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If the thermostat was "stuck open" why would the coolant read 203 as the highest when that is the temp the thermostat opens? It appears it is opening when it is supposed to.
 
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My2010Ram

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If the thermostat was "stuck open" why would the coolant read 203 as the highest when that is the temp the thermostat opens? It appears it is opening when it is supposed to.
Granted I have not had another 5.7 of the same generation to compare it to I still think the tstat is stuck open. The truck is never at 203 when it’s in motion in the winter, its a good 20 degrees below that mark. Now when I sit in stop and go traffic then it creeps up to that 200 mark but as soon as we get moving again it’s like a 20 degree drop. I’d think if the thermostat was opening and closing the temp wouldn’t sway as far, it’d be more like 195-203. I don’t have a ton of experience with V8’s or Dodge for that matter. This is only my second V8 and my first was/is a BMW 4.4l V8 that runs around 220 degrees. I’ve watched the temp in that car on my scantool and it only varies a few degrees once it’s up to full temp whether driving or idling. That’s why I’m so thrown off by this, just seems like a huge change in temp and the thermostat should keep the engine more closely regulated but by no means am I a pro. Both engines being performance engines even though built for difference reasons I’d assume the cooling systems would operate to keep the sway in temp as minimal as possible. .
 
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My2010Ram

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Or maybe someone already installed a lower temp tstat and as you pointed out it is opening and closing properly…
 
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My2010Ram

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I may be wrong on the 203 in summer time, it may actually be higher than that, I can’t quite remember
 

caulk04

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I wonder if it's operating in the manner it should, but isn't closing completely. It should easily warm up fast enough to not trip the CEL.

Also, idling for 5-10 to warm up really honestly isn't necessary. A minute or two, then just drive gently for a couple minutes till the coolant and oil get up a little.

Also, a 190 t-stat is my preference but I won't remove a working t-stat just for that reason. I'll wait for some other reason to open the system before I swap.
 
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My2010Ram

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I wonder if it's operating in the manner it should, but isn't closing completely. It should easily warm up fast enough to not trip the CEL.

Also, idling for 5-10 to warm up really honestly isn't necessary. A minute or two, then just drive gently for a couple minutes till the coolant and oil get up a little.

Also, a 190 t-stat is my preference but I won't remove a working t-stat just for that reason. I'll wait for some other reason to open the system before I swap.
Could be the case, I hadn't thought about it partially sticking open. I still think a 20 plus degree swing is to much even if the tstat is partially operating. I’m about to pass 100k with this truck and I’ve only had it for a year. It was traded in before all the 100k tune up stuff was do I’m sure so I’m getting around to doing it all plus some. I don’t know when or if the coolant system has ever been flushed out so it’s not a bad idea. Could be all original as far as I know.
 
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My2010Ram

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Okay so for a little more perspective I just drove 20 miles on mostly clear freeway and the temp stayed between 177-181. I’m sitting letting it idle (about 5 min now) and it won’t go above 183. The ambient temp is 51 degrees out.
 
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