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I have a scan tool attached to my OBDII port and can monitor my coolant temperature in my 2019 Sorento SX. I noticed that at turnpike speeds the temperature reads between 215 and 220°F. In my 2013 Sorento that reading was always steady at 185°F. I spoke with the service manager of the KIA dealership and he assured me that this was normal.

If the motor has a 185° thermostat, shouldn't the coolant temperature be at or near 185°? In stop-and-go traffic, the fans are actuated to move air across the radiator to keep the engine from overheating, but at highway speeds there is enough air flowing past the radiator to maintain the proper temperature.

Should I be concerned or is the service manager right?
 

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I wouldn't be concerned, no. 220 is on the high end, but it's still within the general range of most cars. If it was 250, I'd worry.
 

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T-stats are not meant to maintain a set temperature based on their rating, that's just their opening/closing point and is programmed for the best emissions. 220 seems like high normal to me but is the dash indicator slightly to the left of middle? Don't know if the dash gauge is linear or stepped but should still give a fair indication of "normal" temps. I'll have to hook up my scangauge and see what kind of readings I get. My C6 Corvette always ran 220-225, my wife's Accord 195-200, my 4Runner 210-220 so cars seemed to have their cooling capacity "programmed" to get into the best temperature for emission control for that particular engine.
 

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Check your radiator surface for debris that might be blocking it.
Then find out what temp the thermostat is?
The engine under normal highway speeds should be a little higher than the stat. setting.
Under heavy loads(Hills,Towing) it will be higher.
What is it reading around town?
 

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Discussion Starter #5
Check your radiator surface for debris that might be blocking it.
Then find out what temp the thermostat is?
The engine under normal highway speeds should be a little higher than the stat. setting.
Under heavy loads(Hills,Towing) it will be higher.
What is it reading around town?
The car has less than 400 miles. The radiator is clean like new. I'm guessing that the thermostat is a standard one at 185°. Driving around town, the coolant temperature is 210-220°.

The electric fan goes on at 204-206° after a warm-up. Then the temperature fluctuates between 204 and 210° on continuous idling.
 

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Double check with the service department on the temp of the stat. I am sure the operating temps you are describing falls more in line with a 195 deg stat.
 

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Water boils at 212*F , 50/50 mix of antifreeze brings it up to 235* F and 15 lbs of pressure in the cooling system (radiator cap) brings it up to about 275* F. So your 215 to 220 is 55* F from the danger zone Another two factors come into play, a 180* T-stat STARTS to open at approxamatly 180*F but valve does not fully open till about 195*C, and the engine temperature sensor is not near the T-stat it's usually in a spot that runs the hottest so the temps never match. Other considerations are the ECM fan control. The fan is controlled by engine temp sensor, and the fans start running about 35% speed at 200* F and increase speed to full speed at about 220*F. Also under normal level road cruising the fans basically shut down above 45 MPH.
 

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Discussion Starter #9
The electric fan goes on at 204-206° after a warm-up. Then the temperature fluctuates between 204 and 210° on continuous idling.
This means that the electric fan is constantly on, even at highway speeds, where there is sufficient air flow across the radiator to chill the coolant. It would make a lot more sense to decrease the operating temperature to below 200° without affecting engine performance.

I still don't understand that if the thermostat is rated at 195°, why the car runs at 225°. At that temperature it must be wide open. Is the water pump specified properly?
 

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Perfectly normal for the thermostat to be 'wide open' at 'full operating temperature'. Always has been.
The thermostat is there to keep the engine coolant from being too COLD, not too HOT.
 

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.... Driving around town, the coolant temperature is 210-220°.

The electric fan goes on at 204-206° after a warm-up. Then the temperature fluctuates between 204 and 210° on continuous idling.
It sounds like you have a DIY mindset, so why not find an online copy of the KGIS service manual, which will tell you everything you need to know about the spec operating temp range, thermostat opening temps, and of course a whole lot more. I'm not referring to that ridiculous subscription which KIA sells, but rather a full online KGIS copy which is a one-time download purchase. A bit of research should be able to locate a source for your specific vehicle's manual.
 

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I still don't understand that if the thermostat is rated at 195°, why the car runs at 225°. At that temperature it must be wide open. Is the water pump specified properly?
The thermostat isn't "rated at 195".. it simply opens fully at 195. That means your engine is expected to run 195 or hotter. Also, the thermostat is a mechanical part that provides no feedback to the computer. The computer just assumes it opens, and takes a temp reading from the engine coolant temperature sensor. If that sensor is reading 225 and the computer isn't causing a check engine light (or some other warning light) to go on, you're fine. That means the computer thinks 225 is ok.

Also, look at any coolant tester.. the high range is well beyond 225. You're not in any danger.
 

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T-stats are not meant to maintain a set temperature based on their rating, that's just their opening/closing point and is programmed for the best emissions. 220 seems like high normal to me but is the dash indicator slightly to the left of middle? Don't know if the dash gauge is linear or stepped but should still give a fair indication of "normal" temps. I'll have to hook up my scangauge and see what kind of readings I get. My C6 Corvette always ran 220-225, my wife's Accord 195-200, my 4Runner 210-220 so cars seemed to have their cooling capacity "programmed" to get into the best temperature for emission control for that particular engine.
the temp gauge is junk for anything close to an accurate measurement.

Connect a scan tool of any kind (Torque?) and you will find that the stock temp gauge goes to its "normal position" of just below half for anything starting at about 65c. I've never had mine go any higher than the stock normal position from 65 to 92C (I've never seen my car higher than that)

note

92c = 198F, 65c = 149F so your car is running plenty warm for sure.

.
 
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