Pretty much correct. The optimal operating temperature for any internal combustion engine is as high as is possible without causing damage to some part of the engine. This varies with the engine, and might be, for example, block or head distortion due to local boiling, or lubrication failure (not likely with modern oils, but still possible), or, on petrol engines, preignition.
Generally a good idea to have a margin between the operating temperature and the temperature where damage starts, but this margin need only be about ten degrees.
So the ideal cooling system does not overcool, but allows temperature to rise rapidly to this optimal temperature, even starting from below freezing. However, since it also has to have sufficient cooling capacity to avoid exceeding this temperature in 50 degree temperatures, while heavily loaded at low speed in sand, what is needed is an effective thermostat.
In practice though, owners generally prefer a system that overcools, as while this results in excess fuel usage and excess wear, unlike a system that allows overheating, it is not likely to result in catastrophic engine failure.
John
Last edited by JDNSW; 18th August 2014 at 01:37 PM.
Reason: grammar
John
JDNSW
1986 110 County 3.9 diesel
1970 2a 109 2.25 petrol
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