I was wondering if anyone has ever had this problem before. Just yesterday my 97 explorer 4.0L SOHC began running hot. Along with running hot it is idling at 1000rpm's around 500 more than normal. Any clue what my problem could be Senor, Thermostat? There is no loss of coolant. Belt looks fine. And fan is operating.

Thanks,
John

 

 

John, I had a similer problem. Out of the blue I experienced the same sympthems that you describe. It turned out to be the clutch fan. It was worn out and did not provide much cooling and the lack of normal resitance drove the rpm's up. I replaced the fan and the thermostat due to a close overheat. Ford recommends that you replace the thermostat any time you get over the 180 degree regulation of the system. Good luck.Jeff

 

Actually his '97 should have a 190F thermostat. That is the temperature it should be fully open at. My '97 maintains a temperature of 190-200 regardless of whether the outside temperature is 35F or 120F. Mine experienced the same problems though last March. I first noticed my RPMs were running around 1100 when I came to lights. Normally it idles around 600 RPM. After a week of this, I took it to Ford, who couldn't find anything wrong with it. The next morning on my way to work, I hooked up my scanner to diagnose it myself. When scanning through the sensors at a red light I noticed my temperature was 240F. I looked at the guage and sure enough it was right next to the red area. I drove straight back to Ford. After argueing whether or not 240F was very far off from what Ford intended my engine to run at, they agreed to look at it again. That is when they found my thermostat was stuck closed.

Check your upper radiator hose. If it is only warm or cool after several miles of driving, I'd bet it is your thermostat. Also, does the RPM only climb up after about 3-5 miles? If so that was another sign. Once the engine gets up to and then exceeds normal operating temperature your computer will bump up your idle to try and draw more air through the radiator.