I hooked up my handheld code reader that reads live data for the first time since I bought the Prius 9-14-12. I drove the car home from work (15 miles) and parked it at 530. Left the house at 7 to go to Sams Club, which was 20 mile round trip - Its 39f degrees out. The whole time, which included 2/3 of the trip there on the highway at 75mph, my ECT (coolant temperature) on my ICE never went above 185f. I have my upper grille completely blocked and my lower 80% blocked. I didnt take the highway back home, I did all city driving (under 45mph) to see if lower speeds would pump up the ICE temperature but it didnt at all. 185f and I saw 187 once when I accelerated. Shouldnt the ICE be getting hotter, especially with my grills being blocked?!
Those coolant temps (FWT on ScanGauge II) are about right. IIRC, I think I've seen it go higher on city drives than highway. I remember doing a highway drive to or from Vegas in over 100 F degree temps and I don't recall FWT being high (somewhere in the 180s or 190s).
Wow...is the cooling system for the ICE that efficient that even with grille blocking the ICE temps wont go above 185f?! GM sure could learn a thing or two from Toyota....
The grill blocking will get the temperature to rise more quickly from a cold start, than without. The thermostat will still control the upper limit, if the engine is not being loaded too heavily. At some point the air flow will be insufficient, but not in MI in winter.
