My 95 has a 160-degree stat and the fans are programmed to come on sooner (via Hypertech). Under "normal" outside temps and freeway driving, the analog temp gage usually hangs just above 185 and the digital reads at about 180. When I turn on the a/c and/or find myself in stop and go street traffic, temps go up but the analog hardly ever gets too much above the 185 tick.

My understanding is that the analog comes from the sensor on the passenger side of the block near the rear of the engine and the digital comes from the sensor just below the water pump on the front of the engine. Moreover, I understand that the signal that is really used by the computer is the one from the front sensor, while the block sensor is only for the analog readout and not really used by the computer.

Anyway, the last week was unusually hot here in the LA area--it got up to 110 where I live. So while driving I turned on the a/c and, of course, temps started rising. The analog got up higher than I had ever seen (more than mid-way between the 185 and 260 ticks) and the digital got up to about 212. Even with the car moving it seemed that the analog would not go back down much and, when stopped, the needle was inching up closer to the 260 tick (digital still read about 212). The analog gauge would only start coming down once I turned off the a/c. What made me more nervous was that with all radiator fans cranking, my volts were dropping much lower than normal.

Questions--do these temps seem normal? I was surprised that once the analog got as high as it did, I could not get it to go down much. Does the coolant system just "give up" once temps get this high?

Another observation, the running of the car at these high heat conditions seemed to have altered the way it runs now that it has cooled back to normal here. The car actually seems to run a bit better and I wonder why.

Thanks,

Doug

 

Not sure on 95's, but there are two temp sensors, one operates the digital gauge (I think its at the water pump outlet) and the other operates the analog gauge (I think its in block). 212 F is a nothing temperature for engines, and is not harmful. It does bother owners though. Turning on the a/c forces the fan/s on, but if you set the temp control to where cold air is vented, then the condenser, ahead of the engine radiator begins to send hot air to the radiator, reducing its heat transfering ability and the coolant temp will rise.
Your temps seem normal to me and nothing to worry about (read your operating manual, GM says to turn off the engine at 260 F and let it cool down).
The analog should have dropped if you could drive above 35mph for a reasonable distance. Stop and go traffic in summer temps just doesn't get enough airflow through the radiator. The fans merely keep the temp from getting to 260.
Even if you had the factory spec 185 (I think) thermostat, you would have seen the same temps, so your 160 thermostat AND the 185 would have been wide open and the coolant temp will rise to the temperature where the radiator gets rid of heat as fast as the engine is making it. The higher the difference between the coolant and outside air, the more heat the radiator can transfer. 160 stats don't do anything for lowering coolant temps in summer temps! I continue to wonder why people think they do and why they bother installing them.
Your engine might be running better because the higher op temps may have cleaned your plugs. C4 and other auto engines should not be run at 160 F.
GM designed C4 cooling systems properly for engine operation, but not for owners. My previous Corvettes, 64, 69, 74, had large radiators and mechanical fans and 180 stats and I could, on a 95 F day driving 75 mph, get off a short exit to a stop light and the temp would stay at 180. Can't do that with a C4, but it shouldn't bother you. Pay attention to the 260 F number though!

 

One of the more annoying things with my car when the underhood temps rise is that loud creaking that suddenly comes from the front end suspension components. I do not know precisely what is creaking but it definitely comes once the temps get high enough for the secondary fan to come on. If I pop the hood and push up and down on the frame, the creaks are very evident. Inside the car, if I go over even a small bump the car sounds like a junker due to the creaking. The minute the underhood temps go down a bit, the creaks go away.

 

I too was concernerd that my '95 LT1 was running "hot' 200-215. Just read today inAug 08 Corvette Fever tech Q&A thatGM kept temp high partialy to help emissions and "numbers out the tailpipes"