Radiator and Engine Cooling

The cooling system of a car works by sending coolant through the engine block & head passages. The coolant flows through the passages and the engine heats the coolant. The heated liquid passes through a hose to the top of the radiator, and then flows down through tubes in the radiator; the hot coolant is cooled by the air stream entering the engine compartment from the grill in front of the car. Once the coolant gets to the bottom of the radiator and is cooled, it returns to the engine through a rubber hose to absorb more heat.

The Radiator

Most modern vehicles have a radiator made of thin aluminum tubes with fins that zigzag between. The air goes through the fins by cooling fans, which causes the heat to be transferred into the air stream, and taken away from the car. The radiator has 2 compartments: one for heated coolant, and one for cooled coolant.

The Pressure Cap and Reservoir Tank

You'll notice the cooling system in your car is sealed. When the coolant gets hot it creates an increase in pressure in the cooling system as it expands. Coolant is made with Ethylene Glycol, which has a higher boiling point than water, Coolant under pressure also has a higher boiling point than when it's not under pressure. These things allow coolant to safely reach temperatures above 250 degrees!

The pressure cap is what allows your coolant to remain at pressure to a certain point. If the pressure builds up too high, the pressure will release via a spring loaded valve. During this process, a small amount of coolant will go into the reservoir tank (not pressurized). Since there is less coolant as the engine cools down, a partial vacuum will form. The radiator cap on these systems has a secondary valve to allow the vacuum in the cooling system to take the coolant back into the radiator!

The Water Pump

A water pump is a simple device that will keep the coolant moving through the system as long as the engine is running. The pump is driven by either a fan belt which usually drives another component, a serpentine belt which drives all components, a timing belt, or in some cases gear driven.


The Thermostat

The thermostat is simply a valve that measures the temperature of the coolant and, if it is hot enough, opens to allow the coolant to flow to the radiator. If the coolant is not hot enough, the flow to the radiator is blocked and fluid is directed back to the engine via a bypass system. Because flow to the radiator is blocked, the engine will reach operating temperature sooner and, on a cold day, will allow the heater to begin supplying hot air to the interior more quickly.

The Heater Core

The hot coolant is also used to provide heat to the interior of the vehicle when needed. The heater core looks like a small version of a radiator, connected to the cooling system with a pair or rubber hoses. One hose brings hot coolant to the heater core and the other hose returns the coolant back to the engine. A fan called a blower, draws air through the heater core and directs it through the heater ducts to the interior of the car. Temperature of the heat is regulated by a blend door that mixes cool outside air or air conditioned air with the heated air coming through the heater core.

Signs of Overheating:

The temperature gauge. If you notice or engine is running hotter than normal, it's time for an inspection.
Check to see if any green, orange, or yellow fluid is leaking from under your vehicle. If it is you are probably losing coolant and should get it inspected.

Squealing noise when engine RPM increases. Could mean a loose belt which would cause poor circulation of the water pump.
Advance Automotive technicians inspect your cooling system as part of our famous 21-Point Inspection that they perform during every service visit. Your cooling system should be serviced annually to prevent overheating that can severely damage your engine.

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