A car's engine has numerous moving parts, and where there is movement there is friction. Friction creates heat. Motor oil is pumped throughout the engine block to provide some lubrication, but it isn't enough to overcome all of this excess heat energy. As a result, parts of the engine become boiling hot as part of normal operations.
This is where the radiator system comes into play. The engine block must be kept relatively cool to avoid serious problems like overheating and seizure. If the pistons cannot slide freely in their cylinders due to excessive friction, they will eventually snap and cause total engine failure. To prevent this from happening, a mixture of water and anti-freeze is pumped through chambers in the engine block to absorb the excess heat and draw it away from vital areas.
The hottest part of any internal combustion water cooled engine are the cylinder heads. The engine block is the second hottest part.
When you start a cold engine the water-pump circulates coolant through the heater-core, engine block and cylinder heads first before the coolant comes up to the opening temperature of the thermostat at which time the coolant flows through the RADIATOR to cool it back down.
When you engine is running it produces a massive amount of heat. The radiator, and cooling system as a whole, keeps the temperature of your engine from overheating.
To keep the engine from overheating and melting down
It keeps the engine cool, so it won't seize up from the heat.
Where else you going to heat up your a** from? Lol.
