Engine has 190 degree t-stat, but temp reads 180?

[Klutch9]

This is for my 2016 Explorer 2.3L. Using a Scangauge II, I’ve always monitored coolant temp in this engine, and it quickly climbs to 180 and stays there. Tomorrow it’ll hit 100,000 miles, and while thinking about maintenance, I realized that there are 3 thermostats offered for this engine: 170, 180, and 190 degrees. 180 seems to be advertised as the normal one, but it’s hard to tell. Ford only sells one thermostat for this engine, and this part is shared with the Focus RS. Ford’s parts site doesn’t list a temp for it, but many other sites that sell the OEM part list it at 190 degrees. @bdcardinal also confirmed that the part listed is 190. So I ordered one.

I thought maybe my original one was just lazy, or maybe it had a cooler t-stat somehow… vehicle does have a tow package. But the part that came out and the one that went in are the identical Motorcraft part. And after burping the cooling system, the temp still sits at 180. Weird!

When viewing live engine data, our Carnival for example will give two coolant readings that vary by 10-15 degrees. I’m thinking this is radiator in/out, hence the difference.

The Explorer’s oil temp also runs really cool, so I was sure it had the lower rated t-stat. But I guess not.

 

[rijndael]

Do you have a coolant temp sensor or is it inferred / calculated?

 

[SC Maintenance]

If it were actually too low you should get a P0128 code (temp too low). So I wouldn't worry about it.

 

[Klutch9]

Do you have a coolant temp sensor or is it inferred / calculated?

Yes actual coolant temp sensor.

 

[The_Jeff]

Do you have a coolant temp sensor or is it inferred / calculated?

It should be legit, it's a cheap sensor and critical to engine operation.

 

[Klutch9]

If it were actually too low you should get a P0128 code (temp too low). So I wouldn't worry about it.

True. One of the reasons I replaced it was because as I stated in another thread, the oil temp in this engine is really low. Unless you are idling in hot weather, or absolutely hammering it, it’s hard to get the oil over 180 (measured at the oil filter using an oil temp sensor I installed).

 

[rijndael]

It should be legit, it's a cheap sensor and critical to engine operation.

Other Ford engines, like the Coyote, have a cylinder head temp sensor but not a coolant sensor.

 

[Brian123]

Thermostats on cars kind of open when they open, meaning a 190 might open a bit sooner. Where is the scan Guage taking the temperature? Here is what you can do before changing the thermostat, you will need an infrared gun, on my car the thermostat is on the lower side of the engine. When you go for a long drive see what the scan gauge shows and then take a reading where the coolant pipe comes out of the Intake Manifold.

 

[tcp71]

Thermostats aren't on/off devices either. They may start to open 10 deg before the rated temp and be fully open by the rated temperature. If you're using a scangauge to monitor temps, there must be some fluctuation based on driving style, traffic and ambient temps. Using my scangauge II on the F150, running temps vary between 195F and 210F depending. Up to 230F towing heavy in the summer. If you're sitting exactly at 180 all the time, confirm the scangauge code or create your own Xgauge as you may be receiving the weighted number. I have the scangauge hooked up to the macan right now and the gauge display shows 90C while scangauge varies between 82 and 110C.

 

[SC Maintenance]

True. One of the reasons I replaced it was because as I stated in another thread, the oil temp in this engine is really low. Unless you are idling in hot weather, or absolutely hammering it, it’s hard to get the oil over 180 (measured at the oil filter using an oil temp sensor I installed).

Do you have an oil temp spec or another car the same to compare to? 180 might be as designed ?

 

[bdc101]

Thermostats aren't on/off devices either. They may start to open 10 deg before the rated temp and be fully open by the rated temperature. If you're using a scangauge to monitor temps, there must be some fluctuation based on driving style, traffic and ambient temps. Using my scangauge II on the F150, running temps vary between 195F and 210F depending. Up to 230F towing heavy in the summer. If you're sitting exactly at 180 all the time, confirm the scangauge code or create your own Xgauge as you may be receiving the weighted number. I have the scangauge hooked up to the macan right now and the gauge display shows 90C while scangauge varies between 82 and 110C.

I was going to say this... if you've ever tested a thermostat in a pot of boiling water you know it gradually opens over a pretty wide range of temperatures. They are not precise devices, and that's by design: you don't want all that cold water in the radiator getting pumped into your hot cylinder head all at once when the thermostat reaches exactly 190 degrees. You want it to mix in gradually and slowly until it's pretty close to the same temperature as the hot engine.

 

[dubber09]

T stats are not precise, temp sensor is not next to t stat either.

 

[tcp71]

Do you have an oil temp spec or another car the same to compare to? 180 might be as designed ?

Unless you have an oil warmer/cooler like this where the oil flows through the coolant (only an example shown), the oil temperature won't match the thermostat temperature...usually being quite a bit cooler as it looses heat through the oil pan. It can be hotter, but only if you're towing or flogging the car at the track in most cases.

 

[Klutch9]

Unless you have an oil warmer/cooler like this where the oil flows through the coolant (only an example shown), the oil temperature won't match the thermostat temperature...usually being quite a bit cooler as it looses heat through the oil pan. It can be hotter, but only if you're towing or flogging the car at the track in most cases.

View attachment 336126

No my Explorer doesn't. That could be why. Our Carnival does, and the oil gets real hot.

 

[Klutch9]

Thermostats aren't on/off devices either. They may start to open 10 deg before the rated temp and be fully open by the rated temperature. If you're using a scangauge to monitor temps, there must be some fluctuation based on driving style, traffic and ambient temps. Using my scangauge II on the F150, running temps vary between 195F and 210F depending. Up to 230F towing heavy in the summer. If you're sitting exactly at 180 all the time, confirm the scangauge code or create your own Xgauge as you may be receiving the weighted number. I have the scangauge hooked up to the macan right now and the gauge display shows 90C while scangauge varies between 82 and 110C.

It actually does fluctuate, normally between 179 and 184 just driving around normally.

 

[zzyzzx]

You do realize that thermostats open and close via a wax ball melting... It's not super accurate.

 

[D60]

Scangauge should just be pulling generic OBD? Would be interesting to see if the "Ford side" thinks the temp is the same or is manipulating it via The Science (TM)