Engine temp

[94 explorer xlt]

When I was getting off the highway I noticed that my fan was running continuously and then I came up to a traffic light and and seen that my temp gauge was climbing steadily so I got it stopped and shut down and waited till it cooled down the temp gauge did not red line or anything and it did not over heat.

I know it might be a thermostat that is stuck open or my water pump took a dump there is nothing in the oil either so my question is is there any sensor or anything like that that I need to know about to. Thanks in advance ( 2008 4.6 V8)

 

[berny13]

Could be a few things. Thermostat is the obvious. Could also be the temperature sending unit, air in the system or even a small hole in the radiator causing a pressure leak. There is also a great thread in this forum for a similar issue:

Temp Indicator Spikes and Engine Revs

Berny

 

[RJ]

Need a bit more info.

Is the rad cap working right? (hoses firm?)

If the fan is stuck on direct drive, carefully feel the air blown by the fan - is it warm or cool?

If the air is cool, then likely you have a partially stuck thermostat and not enough water is flowing through the rad.

 

[Explorer0693]

Might be time to buy a new radiator

 

[94 explorer xlt]

I did leave some info out. After I let it cool down for a bit meaning about 10 or 15 min. the temp gauge did stay at normal and the fan never did kick back on it was only a 5 min ride the rest of the way home. I did not feel to see if rad hoses were firm or not ill run it this morning and see what happens thanks.

 

[pzy3339]

I am having this problem as well right now. Has happened three times in the past 18 months ive owned the truck. Third time was today. Going to replace the sensor and thermostat after work tomorrow. Or perhaps tonight if I feel like it.

If interested I would be happy to detail the work for you after its done. Might save you a few minutes. As of right now I can tell you the Motorcraft parts direct from a local Ford dealership cost $43 with tax. No big deal if it is the cure.

I for one am fairly convinced it is the sensor giving false readings. For what reason I do not know. The rate the temp gauge rises and falls during this issue does not seem to be very likely to be really happening to the engine. I have had an engine blow the radiator apart from overheating due to a blown head gasket and once it hit the red line and I shut the engine down it stayed in the red for a while. The explorer will return to normal temp readings after shutting down and letting it sit for less than 5 minutes. It cannot dissipate heat at that rate with no air flow. Simply impossible. That said, if the sensor is not faulty and there is some reason it is giving false readings despite being in perfect working order that is hard for me to find an explanation for. The air pocket thing is an interesting idea.

Could also be the thermostat not cycling properly, but that I believe to be less likely since it does not truly seem to be overheating.

 

[pzy3339]

Also, after shutdown and restart I have noticed the condition to return if its not let to sit quite long enough. But if I let it sit a solid 5 minutes the issue goes away and does not return.

I recognized it starting this last time(today). Temp was normal, but fan was running hard when pulling away from a stop. I knew then to watch the for the temp to start climbing, which it did, quite fast. Did a few short stops to shut down on the way home, after which the condition returned every time. Then stopped for gas and viola! Problem solved for the day. Weird stuff.

 

[94 explorer xlt]

Well I replace the thermostat and gasket yesterday and before I installed the new thermostat I took the new one and old one and put them in water to heat them once temperature was reached the new open just fine and the old one opened but just the tiniest bit so I mean I had to take it out of the water and look close to see if it actually did anything so I had a stuck thermostat. Put the new one in refilled coolant took it for a drive up and down big hills for about 2 hours and everything is normal temp gauge stayed normal the whole time and never heard a thing from the fan.

 

[RJ]

the old one opened but just the tiniest bit so I mean I had to take it out of the water and look close to see if it actually did anything so I had a stuck thermostat.

Bingo. That's exactly what I meant when I said a "partially stuck thermostat and not enough water is flowing through the rad".


pzy3339,

I replied to your other thread with the exact same suggestion. You may want to hold off on the sensor replacement - they rarely go out.

Do the thermostat first.