fortitude

Changed out the original thermostat + gasket with new OEM.
Two points - the dealer said my original 90916-03129 has been replaced/updated with 90916-A3003. Looked slightly different on how the nose piece is attached but same size, temp range, etc.
Second, originally my temp gauge would rise to middle line when hot then electric fan would kick in and dial would go down to one line below. Now seems like temp reaches middle line on gauge, fan kicks in for a period then cycles off with the gauge remaining on the middle line. Drove it on freeway, no overheating heating. Is this more consistent with how theses car run?

Oro

Reading between the lines, it sounds to me like the new thermostat is just more responsive than the old, tired one.

Nothing was wrong in either scenario, it just sounds like the new one is "feathering" more sensitively to coolant temp.

BDSL

Its normal....

fortitude

I placed it in boiling water to see the function. It was "notchy" opening/closing. The pictures show debris on post in the open position and rubbing (shiny section) on the metal cylinder

funcrusher

How did you know it was having issues? My temp always stays right underneath the halfway mark. Like I have to stick my head on top of it to see that it's barely underneath the halfway point.

fortitude

I have brief fluctuation in idle at cold start and wanted to check coolant temp sensor which requires taking off air box, etc. So while I was there, figured I would do the thermostat+gasket (OEM $28). The car has 145K miles on it.