I have a 02 mercury grand marquis 4.6 v8 w 97 k miles. Been in my care since new. Just did a bunch of fall maintainance myself, oil , trans fluid , tires , front brakes, alternator and belt and tensioner pullies.

Today wisconsin 25 degrees and 6 inch snowstorm. I noticed the car temp guage went down to just barely inside normal on the freeway at 60 mph. Heat in the car was fine. Then i idled a while while my daughter did some grocery shopping and the temp guage was just slightly over the center.. and heat coming out was very hot.

I got home and cooled the car down and checked coolant level and its completely normal. No coolant loss.. no stuff other than clean oil on the oil dipstick. Nice red trans fluid on that dipstick.

So i am thinking maybe a bad thermostat... ordered one , RT1234. Motorcraft, and a new O ring RG571 motorcraft..

My guages seem good, no big fluctuations.. so i dont think i have a voltage regulator issue... does this car still have a voltage regulator ??

Any ideas ?? Thanks

Scott in wisconsin

 

Yes it does. It is located inside the alternator. BUT,,,,,,,,,, is controlled by the Powertrain Control Module (vehicle computer) based on info it receives from the charging system.

 

seemed ok but i did not boil it to check it out