do the engine gauges still work properly?

[robtek]

My idea about the lowered allowed temps at alt. is simple that the thinner air can't transport enough thermal energy.

So, as the outlet-temperature of the radiators is the important value here (it is known how much thermal energy will be produced)
the pilot must control the indicated inlet temperature to a point where the radiator is able to cool the coolant to the needed max. outlet-temp.

[II./JG1_Krupinski]

Just an observation with the 109 coolant system. When taking a hit I've noticed the coolant escaping and when finally all coolant being evacuated, the water temp gauge would show it completely off the right side(as high as it could be).

In my observations of real life coolant failures (in automobiles however) this is the exact opposition. The gauge should be showing the minimum temperature.

[robtek]

That depends where the sensor is mounted, at the engine -> heating up without cooling, or in the coolant circuit -> cooling down without fluid to transfer the heat.