Explorer thermostat rises on freeway lowers on city streets

FORD EXPLORER
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QUINNZ51
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  • 2 POSTS
I have a 2000 ford explorer 4.0 liter 4wd 126000 miles. Due to the colder weather I have had to use the heat and have noticed the thermostat acting funny. When I am on the freeway doing 65 mph the temp reading is normal, but when I go to a slower speed or I am slowing down or coming to a stop the temp reading goes down. Any ideas on whats going on before I take it to the dealer? By the way the heat is working fine no problems. Thanks!
Oct 25, 2006 at 1:12 AM
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QUINNZ51
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UPDATE!!! UPDATE!!!! UPDATE!!!!! UPDATE!!!!
I replaced the thermostat and everything seems to be fine. Which raised another question: Was the thermostat "starting to go bad" versus a thermostat "going bad?" I have no idea.
Oct 25, 2006 at 5:01 AM
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CATCH_15
  • ✓Experienced Mechanic
  • 250 POSTS
The reason it was running at normal temp on the highway is because there was air circulating through the engine bay. Not the cas in the city. When a thermostat goes bad, it usually will get stuck either open or closed. If it's stuck open, the car will run very cool because the thermostat is letting a free flow of coolant. If it's stuck closed, the car will overheat.
Oct 26, 2006 at 4:31 AM
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