LO 11-2 Identify and explain the purposes and functions of the cooling system

1.14. Freezing and Boiling Protection

Freezing and Boiling Protection

Because water is the primary ingredient of engine coolant, the engine requires protection from frozen and boiling coolant. Frozen coolant easily breaks and cracks cylinder heads, blocks, water pumps, and radiators. Additionally, it pushes out core plugs, sometimes called frost plugs , which causes a major loss of coolant. It should be noted that core plugs are not designed to relieve pressure resulting from frozen coolant in order to prevent engine damage. When coolant is frozen in areas such as the radiator or a hose, it will not allow system flow, which causes the cylinder components to rapidly overheat, thereby thermally stressing the cylinder block and head to the point of cracking. Conversely, boiling coolant is not able to effectively absorb heat because it is not in a liquid state. Protection against freezing and boiling are both provided to the engine by the use of antifreeze TABLE 11-1. Additional protection against boiling is accomplished by pressurizing the cooling system.