2002 mercury cougar "over heating"

[AFoster]

about three weeks ago we thought our cougar was overheating, but determined it was the coolant temp sensor on the engine block. i switched it out and it hasnt had a problem until now.
now we are getting the same symptoms as before, the heat gauge max's out soon after running the car, but the engine isnt even hot to the touch yet.

any ideas of what to start checking next?

also i changed the thermostat thinking that was the problem last month. and the coolant has been drained and replenished, tried to wash out the radiator with a garden hose. believe the car has had stop leak put in it before as the coolant had junk in it

[cancritter]

l would check wireing to enshure its not grounding out through a melted wire to start...dosnt sound like fan clutch or thermostat and cant see stop leak haveing that sorta affect on cooling unless they went nuts and poured a few cans in there

[AFoster]

i dont think its the stop leak causing the problem either, just thought i would put all the info i had.
i didnt notice any melted wires going to the sensor, or any wires in the top of the engine bay. but will check into that.

i know its a problem with either the gauge, or a sensor somewhere, or wires in betweeen as the engine is not overheating, the gauge just says it is. i have used a heat gun, and never get numbers above 190 F and the most recent time we had only drove for 1 mile when the gauge maxxed out, i got out and could put my hand on top of the engine, it was warm but no where near hot, probably only 100 degrees

[cancritter]

sounds more like a electrical issue more than anything,,,,would try and find some way to test sensor and gadge...little mickey mouse here but l would try to find some way to heat up sensor outa vehicle while its still hooked up and see how the gage reacts....could verywell be the gage itself....at that point would hit local wrecker and look for replacement cluster...must be a way to test gage with altimeter but thats beyond me but someone around here may have better idea how to...anyway with heat gun all seems to be fine for most part so belive its electrical over mechanical issue