[Josh]

Got a doozy for y’all. 2013 Chrysler Town and Country 3.6l. I changed the thermostat 4–5 years ago. Been doing perfect then last week the best guage randomly went up to 3/4 for 2 min then back down to half, then continued to do that once an hour or so, with the exception one time it went a little about 3/4. But it always went back down.

I changed the thermostat I noticed the spring was noticeably bigger then the old one, but I put it on anyways, then it made the heat guage fluctuate even worse before doing it every 20 to 30 min even went to almost red, so I suspected the spring was too big so I changed it back to the old spring but with the new thermostat.

Both rated at 203f, and I turned on AC and saw the cooling fan turn on as it should, so… What’s next? Why did it do it worse with the new thermostat?

**UPDATE**

After taking the thermostat back out and changing just the spring because, I did notice the new spring was pretty damn big. I haven’t had any issues.

[Mike]

Are you sure there is only 1 thermostat? I’m not familiar with that vehicle, but something to rule out. If not, I’d suspect the water pump or air lock in the cooling system.

[Copacabana]

Sounds like there’s an air pocket, fluctuating gauge is a dead giveaway of that.

[Mike]

My guess would be a fan not working as it should or a water pump issue.

[David]

The gauge on the dash works by the temperature sensors, not the thermostat.

[Abraham]

Also, NEVER let your vehicle get to 3/4 or above. That’s asking for a blown head gasket.

[Author]

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