Proper operating coolant temp for a 2010 Ram 1500 5.7

[My2010Ram]

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]

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.

 

[My2010Ram]

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]

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.

 

[My2010Ram]

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. .

 

[My2010Ram]

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

 

[My2010Ram]

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

 

[caulk04]

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.

 

[My2010Ram]

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.

 

[My2010Ram]

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.

 

[CamperMike]

I say the thermostat is at least partially open. It should be warmer than that.

 

[Bigskyroadglide]

In my humble opinion, you've owned the truck for a year. You're approaching 100k.

Change the T stat, flush and fill the cooling system and then you will know.

Otherwise you are guessing.

If it continues to exhibit the behavior, then it's something else.

A flush and fill with a new t Stat is reasonable at 100k on the clock. Especially if it gives you peace of mind.

PS, the stock tstat is 203 degrees.

 

[My2010Ram]

In my humble opinion, you've owned the truck for a year. You're approaching 100k.

Change the T stat, flush and fill the cooling system and then you will know.

Otherwise you are guessing.

If it continues to exhibit the behavior, then it's something else.

A flush and fill with a new t Stat is reasonable at 100k on the clock. Especially if it gives you peace of mind.

PS, the stock tstat is 203 degrees.

That’s what I was thinking too, it’s time for the big tune up. If I knew that the swing in temp that I have been seeing is relatively normal then I’d leave the Tstat alone and just flush the system. But for a $10 part that relatively easy to get to I think it would be a mistake not to change it since the system needs to be emptied anyway.

 

[Tominator223]

I have a 04 5.7. I run the 180 or 190. It hot climate se tx. I did this to avoid the valve seat issue. (In 3rd gen) However you may just have a bad sending unit(sensor). Or sensor may just be lazy. That’s where I’d look.

 

[Wmjohn]

Why not install a new 190 or 205 tstat?

 

[crash68]

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.

You already spelled out the problem, when your getting a CEL because the ECM is saying the temperature is too low then it's either the thermostat isn't working correctly or the coolant sensor is bad. Since you'll need to drain the coolant down to change either one might as well do both, use Mopar parts.
You shouldn't be seeing a CEL if you don't warm the vehicle up, I've had a similar code on other vehicles and the fix was the thermostat.

 

[Serespecialist]

I’m from Florida and when I visit North Dakota I put cardboard in front of my radiator so I have heater working otherwise it blows cold air lol

 

[Rambo71]

I just had my water pump replaced, they did the thermostat while they were in it, it runs consistently between 198-204, climbed up a mountain and saw 210 once.
Also check your active shutter system to see if they removed or disabled the shutters. Could be wide open shutters with a 180 thermostat.

 

[GTyankee]

When you do decide to to change coolant

You should back flush the heater core, that is the 2 hoses that pass through the fire wall.

You should be using HOAT Coolant in a 4th Gen 2010 Dodge Ram
this will work properly for your truck
Zerex G-05 by Valvoline
Valvoline actually makes HOAT for MOPAR

Spend a bit more & get the correct thermostat for your truck

Good thermostats made in recent years, when they FAIL, they fail in the OPEN position, unlike thermostats of the past, that failed in the closed position

 

[My2010Ram]

Finally got around to to doing the job, running at proper temp now and getting there faster. I replaced my tensioner and idler pulleys, pvc valve, the old pulleys were fairly worn out. I discovered my water pump pulley bearing was going bad too. It wasn’t leaking yet but there was just enough wobble on the pulley that I knew what was coming. So I replaced the water pump and put a stock temp t-stat as well. Sounds a lot quieter and the idles feels smoother too. Wish I had done this several weeks ago before the cold snap. Now all I have left is to do the spark plugs. Thanks for everyone’s input!