Explorer thermostat rises on freeway lowers on city streets

QUINNZ51

MEMBER
FORD EXPLORER

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!

2 Replies

QUINNZ51

MEMBER
2 POSTS

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.

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Wednesday, October 25th, 2006 AT 12:01 PM

CATCH_15

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.

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Thursday, October 26th, 2006 AT 11:31 AM