Editing Internal combustion engine cooling (section)

== Overview ==
[[Heat engine]]s generate mechanical power by extracting energy from heat flows, much as a [[water wheel]] extracts mechanical power from a flow of mass falling through a distance. Engines are inefficient, so more heat energy enters the engine than comes out as mechanical power; the difference is [[waste heat]] which must be removed. Internal combustion engines remove waste heat through cool intake air, hot exhaust gasses, and explicit engine cooling.

Engines with higher efficiency have more energy leave as mechanical motion and less as waste heat. Some waste heat is essential: it guides heat through the engine, much as a water wheel works only if there is some exit velocity (energy) in the waste water to carry it away and make room for more water. Thus all heat engines need cooling to operate.

Cooling is also needed because high temperatures damage engine materials and lubricants and becomes even more important in hot climates. Internal-combustion engines burn fuel hotter than the melting temperature of engine materials, and hot enough to set fire to lubricants. Engine cooling removes energy fast enough to keep temperatures low so the engine can survive.<ref>
{{cite web
 |url         = http://www.worktrucksales.com/infocooling.htm
 |title       = cooling system
 |website     = worktrucksales.com
 |access-date = July 13, 2017
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20170914063953/http://www.worktrucksales.com/infocooling.htm
 |archive-date = September 14, 2017
}}
</ref>

Some high-efficiency engines run without explicit cooling and with only incidental heat loss, a design called [[adiabatic process|adiabatic]]. Such engines can achieve high efficiency but compromise power output, duty cycle, engine weight, durability, and emissions.{{citation needed|date=February 2014}}