Definition
An engine cooling method in which a liquid coolant is circulated by a pump through passages (jackets) surrounding the cylinders, absorbing heat from the engine and carrying it to a radiator where it is released into the airstream before the coolant returns to the engine.
Plain English
The engine is kept from overheating by pumping liquid around its hot parts. The liquid soaks up heat, flows to a radiator where the air cools it down, and then loops back to do it again.
Context Anchor
Seen in reciprocating engine discussions when comparing engine cooling methods, especially liquid-cooled versus air-cooled engines.
Why Pilots Care
Liquid cooling maintains steadier temperatures across operating conditions, which can reduce thermal stress and improve reliability, though the system adds weight, a radiator, and a pump.
Analogy
It works much like many car engines: liquid carries heat away from the engine, and airflow through the radiator helps remove that heat.
Intuition Check
Liquid cooled does not mean the engine is cooled by fuel or by simply being wet. It means a dedicated cooling liquid is circulated through the engine to carry heat away.
Example Sentence 1
Most piston aircraft engines are air-cooled, but some high-performance models are liquid cooled for more consistent cylinder temperatures.
Example Sentence 2
Before flight the pilot verified the coolant level in the liquid cooled powerplant.