In order for the miracle of the automotive cooling system to march on unabated all the components must be able to hold up under pressure. The heavy hitter in this equation is the radiator. Inside the radiator are coolant passages. Connected to the passages are the cooling fins. As hot engine coolant passes through the radiator heat gets wicked away through these fins and into the air. Neglecting the cooling system can cause corrosion and even rust to build up inside the radiator until one day it literally cracks under pressure and makes like an underhood Old Faithful. Pressure and tempers are lost along with engine cooling.
A regular check of coolant level will indicate if the system is holding its own. Check the coolant only when the engine is cold, and on a level surface by removing the radiator cap and peering inside the filler neck. Never open a cooling system when the engine is hot. If the coolant level in the radiator or coolant reservoir is below normal, or if there are the tell tale signs of coolant leakage on the garage floor first inspect the radiator and heater hoses and water pump for leaks. Take a good look at the hose clamps and make sure they're snug. A leaking system cannot maintain the pressure required for coolant circulation. The engine will run hot as hot as a boiling kettle and eat itself up.