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The purpose of the Engine Cooling System is to prevent the overheating of your vehicle’s engine. With engine combustion reaching extremely high temperatures, the resulting heat needs to be dissipated. An efficient cooling system is essential to prevent the engine from burning!! Another function of the cooling system is to regulate the temperature inside the passenger compartment, insuring your comfort and that of your passengers.

On most recent vehicles, the engine cooling system is pressurized. You should not attempt to effectuate maintenance or repair work on the system. Servicing or repairing this system requires specific tools and adequate training. That is exactly what Autotech Performance can do for you!

Main Components of the Engine Cooling System

  • Radiator
  • Cooling Fluid – Coolant
  • Radiator Fan
  • Radiator Hoses
  • Water Pump
  • Heater Core
  • Temperature Knob
  • Temperature Control Valve
  • Thermostat
  • Temperature Gauge
  • Temperature Sensor
  • Reservoir or Reserve Tank
  • Radiator Pressure Cap
Pouring antifreeze in a car.

How does the Engine Cooling System work?

The radiator is the main component of the cooling system. The cooling fluid (or coolant) flows through the inner core of the radiator and transfers its heat to the metal cooling fins that surround the core. The airflow – provided by the radiator fan – that passes through the fins dissipates the heat from the coolant.

Cooling fluid is usually deep green in color but recent coolant formulas are the color of rusty water. Note that it is important to use a type of cooling fluid that is recommended for your vehicle’s particular model. Moreover, you should not mix different types of coolants.

The radiator hoses link the upper and lower parts of the radiator to the engine so that the cooling fluid can flow to and from the engine.

The water pump circulates the coolant around the cooling system and into the engine block. The water pump is usually activated by either a belt located on the crank pulley or a timing belt that turns at about the same RPM as the engine.

The heater core is a small radiator-type device located under the dashboard in the passenger compartment. The temperature knob on the instrument panel controls the temperature control valve located in the engine compartment. Turning the knob toward the warmer setting opens the temperature control valve, allowing coolant from the engine to circulate through the heater core and warm the interior of the car. Inversely, turning the temperature knob toward the cold setting does close the temperature control valve, allowing cool air from the air conditioning system (if the car is equipped with this system) to flow through the heater core and cool the interior of the vehicle.

The thermostat is located in the engine in line with the upper radiator hose. The purpose of the thermostat is to maintain the coolant and therefore the engine at a proper operating temperature. Note that the engine thermostat is not linked to the temperature knob which is controlled by the driver. When the engine is cold, the thermostat is closed, meaning that the coolant is circulated only through the engine and heater core, bypassing the radiator. This is to prioritize the warming of the engine and the use of the defroster and heater in the passenger compartment. Once the engine has reached its optimum operating temperature, the thermostat slowly opens allowing the coolant to flow through the radiator to prevent the temperature to rise higher. As the engine continues to operate, the thermostat constantly controls the flow of coolant to the radiator so that the engine continues to operate at optimum temperature. For instance, the thermostat will open when the engine temperature rises – when you are stuck in traffic – and close when the engine cools – such as when you are cruising on the highway.

The temperature gauge, located on the instrument panel, is linked to a sensor located on the engine block. This sensor registers variable levels of electrical resistance as the engine heats up and allows an accurate monitoring of engine temperature.

An overflow bottle is used as a reservoir for the coolant as it expands and contracts within the system. When hot, the coolant expands and the overflow of liquid is directed to this reservoir. Inversely, when the radiator cools down, the coolant contracts and induces a vacuum within the radiator which then pulls in coolant from this same reservoir. As the reserve tank tends to collect residues from the cooling system, it must be cleaned when the coolant is changed.

The radiator cap closes the filling hole of the radiator through which the coolant is poured. For the entire cooling system to work properly, the radiator cap is designed to seal the cooling system to a specific pressure.

Signs of troubles related to your vehicle’s Engine Cooling System

  • Temperature gauge indicating above normal engine temperature
  • Pool of green, orange or yellow fluid under your vehicle possibly indicating a leak in cooling system
  • No or little heat in passenger compartment