Thermostat on its way out???

[canonball]

During my commute into the office today I noticed the coolant temp hanging out a just a bit cooler than normal. I'd probably been driving for 30-40 minutes at that point so the engine should have definitely been properly warm. As I got a little closer to work it actually came back up to normal. It was quite cold this morning, when I first noticed it the outside temp was at 32° (F). A few months ago I was sorting out a coolant leak issue and in the process flushed the system and topped it off after, did my best to keep the mixture in the car around 50/50, but if it did get a little watered down would that cause the engine temp to dip when the outside temps get colder? Or is this more inline with a failing thermostat?

[Turbo510]

Either thermostat of temp sender. How's the HVAC heat? Does it blow warm-hot after a few minutes of driving?

[canonball]

Either thermostat of temp sender. How's the HVAC heat? Does it blow warm-hot after a few minutes of driving?

Yeah, hvac seems normal. Everything else seems normal, car runs good. It just seems to fluctuate between the 1/4 mark between cold and normal and normal temp, did the same thing my whole drive home.


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[kwilson]

Is your drive downhill? I have had issues before maintaining heat while driving down long mountain passes here in CO during the winter. Outside temps were below zero and using engine braking.

[TobiqueSlang]

it's likely a temp sensor. Mine started doing the same thing after I used it to ford a river once, killed the 2 pin sensor at the bottom of the rad.