What you mean is that the water temperature will be higher when using a diesel generator in high mountains, right?
This is because atmospheric pressure decreases as terrain increases, and the boiling point of water also gradually decreases as altitude increases. (At an altitude of 1,900 meters, the atmospheric pressure is approximately 79,800 Pa (600 mm mercury) and the boiling point of water is 93.5°C.
However, air-cooled diesel engines are generally low horsepower, and those with higher horsepower are generally water cooled. As long as your altitude and load are not very high, high water temperatures will not occur. usually not.