Baffled by Temp sensor

[dleague]

Well, I was driving in on the way to work this morning and got the explorer up to around 80 to pass someone. When I did that the temp sensor chimed and the light came on in the dash to let me know the engine temp was hot. Looked at the guage and it was almost spiked out. I immediately let off the gas and it went down quick. I was going to pull over but it seemed to run fine the rest of the time. I checked everything out when I got to work and it looked fine. Not sure why it spiked like that. never has done this before and didnt do it anymore afterwards. Hoping this isnt any major and maybe just a fluke. Any clue what could have caused this? Any help would be great.

 

[abarkl]

Most likely a sticky thermostat. Mine did the same thing a few years back and I replaced it in about 30 minutes.

 

[JoshMcMadMac]

The temperature gauge is really little more than an analog idiot light...it does not actually indicate temperature. Once the engine is warmed up the gauge will remain set in the middle regardless of 190° or 230°, for example. It will only shift to the 12 o'clock position if it gets hot enough to trigger the warning light.

That said, it would not be surprising for the thermostat to be sticking. It is also possible you have an air pocket in the system.

 

[swshawaii]

I'm sure you would have mentioned steam or leaks if you had one.
Regardless, check your radiator and overflow tank coolant levels.
+3 on an intermittent thermostat. If over 60K, replace it anyway.

 

[matt0248]

The temperature gauge is really little more than an analog idiot light...it does not actually indicate temperature. Once the engine is warmed up the gauge will remain set in the middle regardless of 190° or 230°, for example. It will only shift to the 12 o'clock position if it gets hot enough to trigger the warning light.

That said, it would not be surprising for the thermostat to be sticking. It is also possible you have an air pocket in the system.

I think you are thinking of the oil pressure gauge. The temperature gauge is an actual gauge that moves with the temperature of the engine. My v8 has a cylinder head temp sender that the pcm uses for the engine temp and sends it to the gauge also.

 

[JoshMcMadMac]

I think you are thinking of the oil pressure gauge. The temperature gauge is an actual gauge that moves with the temperature of the engine. My v8 has a cylinder head temp sender that the pcm uses for the engine temp and sends it to the gauge also.

No, the engine temperature gauge does not indicate actual temperature. If you do not believe me, try it for yourself. Get a scanner that will read the actual engine temperature and put a piece of cardboard in front of the radiator to block airflow. You will be able to witness the temperature climb on the scanner while the temperature gauge unwaveringly remains steadfast at mid-range...until you hit the magic number (somewhere between 230°-250° I believe) and the engine protection kicks in, at which time the temperature gauge spikes straight up.

 

[dleague]

Is there anyway to find out if it is the thermostat sticking? There wasnt any steam or leaks. I checked my fluids and they all seem to be ok. It hasnt done it but that one time. My guess is maybe it is the thermostat sticking. Anyone have a diagram of where I find it at on my Explorer? Im new to the Ford ownership and have mainly been a GM person but Im starting to like the Explorer.

 

[JoshMcMadMac]

Is there anyway to find out if it is the thermostat sticking? There wasnt any steam or leaks. I checked my fluids and they all seem to be ok. It hasnt done it but that one time. My guess is maybe it is the thermostat sticking. Anyone have a diagram of where I find it at on my Explorer? Im new to the Ford ownership and have mainly been a GM person but Im starting to like the Explorer.

V8 or V6? Just follow the radiator inlet house to the engine and that should get you to the thermostat. The only way to test the thermostat involves removing it...and if you go in that far, you might as well replace it. You can put the old one in a pot of (almost) boiling water and watch it actuate to see if it is sticking, but that would still not be definitive.