I have a 2006 explorer limited with the 4.6 v8.
I am running into an issue where at revs above 2000 i am getting temp gage fluctuations and full fan speed. The gage will actually climb all the way to hot if i don't slow down and my ac will quit working. As soon as i slow down the temperature stabilizes. It will never get hot idling. I can typically drive around town all day no issue. But if i get on the highway the car temp gage rises.

I've replaced the water pump, thermostat, fan clutch, cht sensor and radiator. I've attempted many times to burp the system of air.

Today i plugged in my obd scanner. At idle with the gage in the middle coolant temp was reading 230f on my scanner. Fan was not engaged fully. Took my infrared thermometer and measured multiple points in the radiator system. Was only reading about 160f on the thermometer.

I'm starting to think i have a bad coolant temp sensor or a computer issue. But all my research has led me to believe there is no coolant sensor on this engine. Only the cylinder head temp which i have replaced. But O'Reilly's lists a coolant temp sensor for my engine car combo.

Can someone enlighten me on what I'm looking at. I think the computer thinks its getting hot and is running the fan full blast and disabling my ac. Any help is appreciated!

 

Update:
Pulled the thermostat tonight. Drove the car 20 miles on the interstate at 80mph to really give it a good test.
Not once did the guage get above the midway point.
My obd scanner indicated 180f once the engine warmed up and didnt climb above that value.
The fan never kicked on at any point during the drive.
Id say i either got a faulty thermostat or the wrong temperature rated thermostat. What are your thoughts on this?

 

I've got a 4.0 sohc (2003) explorer that has a sensor right near the thermostat that reports directly to the ecu. I'd bet your motor has one too. It's a cheap part, replace it and check the wiring for issues.

 

Thanks for the reply jchris. The v8 does not have a coolant temp switch according to ford and my thermostat housing is of a different design than the 4.0 v6(4.0 has a plastic housing with a port for a temp switch, v8 just has an aluminum housing with no port). I wish it were that simple. After bleeding air over and over again I believe I remedied the issue. I guess these 4.6's are a pain to get air out of the coolant system.

 

Hey is this solved? been more than a month.

I would check vacuum. If the vacuum is jumping around, I would go to a cylinder by cylinder leak down test.

 

This has not been resolved.

I took the truck to Ford last week. They hooked up their computers and flashed the pcm. They verified that the truck is not actually overheating but the pcm thinks that it is.

They recommended I place a washer under the cht probe to elevate it out of the head. I did this and it did not fix the issue. They also said that my PCM is testing bad (whatever that means) but that they didn't believe that was the problem.

I'm at a total loss as for what to do. This truck is driving me up the wall. Temp on scanner indicated 230-260f but readings of the thermostat housing and other components indicated closer to 180-190f.

Very weird stuff going on here.

 

You can reference more of the situation in the following forum:
https://www.explorertalk.com/forums/#/topics/51067?page=2