Cooling System

Cooling System

The cooling system removes excess heat to keep the inside of the engine at an efficient temperature, about 200° F (94° C).

Coolant Flows

Coolant flows through the water jackets where it absorbs heat. It then flows through the radiator where heat is transferred to the air passing through. The amount of flow is determined by the water pump. The flow direction is controlled by the thermostat.

Engine Cold

When an engine is cold, the thermostat is cold. Coolant flow is through the bypass hoes and the water jackets. This allows the engine to warm up evenly.

Thermostat Open

The thermostat opens when the engine warms up. This allows coolant to circulate through the radiator and the water jackets.

Coolant Temperature Maintain
  • Maintains operating temperature of approximately 200-235 degrees
  • When temperature is low, bypass blocks coolant flow through radiator
  • When correct temperature is reached, thermostat opens and excess heat is absorbed through water jackets and passed on to air flowing through radiator
Rubber Hose

Reinforced rubber hoses transfer the coolant from the engine to the radiator, coolant reservoir, and heater core.

Radiator Tubes

The hot coolant flows through the radiator tubes and heat is transferred to the fins and then to the air passing through radiator.

Down Flow Radiator

Older vehicles used down flow radiators with the coolant flowing from the top to the bottom. Modern vehicles use cross flow radiators with the coolant flowing from one side to the other.

Upper Gasket

The upper gasket prevents coolant from escaping to the outside. The lower gasket keeps a pressure in the radiator. The cam lock pushes the two gaskets against the sealing surfaces when the cap is installed. The safety stop prevents the cap from being opened to quickly.

Radiator pressure results from the expansion of the coolant as the engine warms up.

Coolant volume increases about 10% as the temperature increases from 70 to 180° F (21-82° C)

The radiator cap creates the pressure by holding the coolant in the radiator.

The coolants boiling point increases about 3° F for each psi increase in pressure.

Radiator Cap

When the engine warms up, the radiator cap allows the expanding coolant to flow in to the coolant recovery reservoir.

When the engine and coolant cool down, the coolant returns to the radiator and water jackets through the vacuum valve in the cap.

Air Flow

Air flows through the openings at the front of the vehicle, through the radiator and other heat exchangers, and exits past the engine. The fan with shroud assists the natural flow when the vehicle goes slow or is stopped.

Coolant Mixture

Coolant is a mixture of antifreeze and water. Antifreeze lowers the freezing point and raises the boiling point.

Coolant also protects the system from rust and corrosion.