What's our normal/average engine coolant temp supposed to be at??

our gauge doesn't have temp numbers on it, and mine is always right in the middle, which is fine...

but I'm looking to find out what that relates to as actual temp... like if I'm logging engine data, what should the engine coolant temp be at??

what is too high??


TIA!!!

 

It will vary considerably. Numbers would just cause people to worry/complain that their car ran hotter or colder than their neighbor. Did a series of experiments with t-stats some years back when I was troubleshooting my XJS V-12 (which has two thermostats and a 2/3-1/3 pass through radiator among other factory band-aids to keep it cool). Anyway, a thermostat is not a fast reacting device, it might take 30 seconds to go from fully open to fully closed. The rated temp is what you get when they are about halfway open and either extreme (open/closed) is about 10F on each side of it. Now, the temp will bounce back and forth as it gets too hot and it opens more, dropping the temp, then it gets too cold and shuts itself slightly restricting flow. It is a bit more complicated with the relatively cold water in the radiator and thermal shock to the block, but even in the more convoluted set-ups, the result is the same. The temp never settles, it is always moving higher and lower, trying to get to steady-state flow/temp. Never happens. It is my experience that most people get all crazy when they see needles bouncing around, so I would design a gauge with a lot of damping in it so that the tiny fluctuations are never seen on it. I suspect a lot, if not all, auto makers do the same.

As far as the logging, you might get an average temp out of all your data, but I suspect it would only be good for your car at whatever constant load you were putting on it. In other words, I don't see any real use for the data. Too high would be ~10F above the rated 'stat temp for more than a 30 seconds of so. That means the heat load is too high for the cooling system to handle and it is wide-open, out of control. Since GM has historically added in at least double the cooling capacity required on their vehicles (to offset scale build up, poor care, etc, I would say after 30 seconds you have a real problem with your cooling system.

 

k... so since our stock t-stats are 187*F t-stats... you're saying/suggesting that our engine coolant temp shouldn't get/show any higher than 197/200* F...

 

Maybe yes, maybe no. The temp at the t-stat should not get above that, the place where the temp sensor is a completely different animal. Could be a local hot or cold spot. You could get an average temp from the sensor and then add your 10F or so and it would be a place to start, but the coolant temp will vary depending where it is in the block as well. Trying to pin down a true representative temp is not really possible.