2002 Grand Prix GT 4-door
3800 Series II non-SC
mileage: 225,181 (yes, that's correct! And I'm the original owner...)
This week I replaced the lower intake gaskets (used Felpro metal gaskets) and the upper intake and gasket. During the repair I also replaced the thermostat and coolant temp sensor. I mixed my own 50/50 Dexcool solution using distilled water (double-checked the Dexcool bottle to make sure I didn't accidentally by pre-mixed 50/50 before diluting).
After completing the repairs, the temp needle at full operating temp hovers and stabilizes between 210 and 235. Is there anything else that I missed that could be causing the overheat?
There is no bubbling in coolant tank that would indicate a blow head gasket, the oil is not cloudy, and the new coolant appears to be clean and not contaminated with any oil. While operating with radiator cap off and thermostat open (I know this is not recommended...) I can observe coolant down in the filler neck coming steadily out of the radiator passages, so that's confirmation to me that the thermostat opens as it should.
One step I haven't tried is to plug the car in to an OBD that can read coolant temp, to determine if I have a false reading on the instrument cluster dial.
I'm considering radiator replacement as the next option, although there are no coolant leaks at this point. My last radiator replacement was in 2011.
I feel like I've been pretty thorough on this repair, but any other ideas?
