Your Engine 101

Car Cooling Systems

Watch Out For Car Cooling Problems

The engine cooling system of your car works to keep your engine from overheating and helps it to operate at its highest efficiency. Your cooling system components include the water pump, radiator, hoses, thermostat, and fan. When parts of your car cooling system fail, your car engine will overheat and could possibly suffer serious damage.

Signs that your car engine is overheating:
  •  The temperature gauge on your dashboard starts to rise
  • Steam comes billowing out from under your hood
  • You hear hissing or pinging sounds
  • You smell antifreeze boiling over
When any of these car cooling problems occur, stop driving immediately and wait until your car cools down. DO NOT, under any circumstances, attempt to open the radiator or pressure cap.

What's a water pump?
Automotive Water PumpThink of the water pump as the heart of your car’s cooling system — working continuously to circulate engine coolant (antifreeze) from the radiator to the engine and back again. A water pump is powered by a V-belt or serpentine belt mounted on the outside of an engine, or by a timing belt located inside the engine.
How do I know if my water pump is failing?
A failing water pump will give you lots of hints. Look for leaking engine coolant around the pump itself or the surrounding engine. (If your car has a timing belt, you won’t be able to see this because the pump and the timing belt that powers it is located inside the engine). In this case, have your automotive service technician inspect and replace your water pump at the same time you’re performing scheduled preventive maintenance on your engine timing belt, hoses or other car cooling system components.
What's a automotive radiator?
The car's radiator helps disperse the heat that the coolant has absorbed from the engine. It sits just behind the front grille of your car. Inside the radiator are a series of tubes (a.k.a. the radiator core), which circulate a combination of antifreeze and water. Attached to these tubes are thousands of little metal fins, which basically help to pull cooler outside air into this area, cooling the fluid in the tubes and releasing the extra heat into the atmosphere.
What's a coolant hose?
Cooling System HoseEngine coolant hoses are reinforced synthetic rubber tubes that are made to withstand the strong chemicals in engine coolant, as well as the high heat, vibration, and pressures that take place under the hood. They work year round to carry antifreeze between the engine, radiator and heater, and help maintain proper temperature.
Where are engine coolant hoses located?
Radiator coolant hoses are located in several places around your radiator and engine. The upper radiator coolant hose delivers hot engine coolant from the engine to the radiator. Coolant then circulates through the radiator, and then exits out the lower radiator hose, which returns coolant to the engine. On some engines, a bypass hose circulates coolant through the engine when the thermostat is closed. Heater hoses carry coolant between the engine and the heater core.
How often should my hoses be checked?
At least twice a year at the start of each summer and winter season. If they need replaced, your automotive service tech can do it at the same time he’s flushing the car cooling system and installing new coolant.
How do I know if one of my coolant hoses needs replacement?
First, look on the outside of your hose — if you see any cracks, cuts, abrasions or bulges, the hose needs to be replaced. You can also feel the hose (make sure the engine is turned off and cool) — if it feels excessively soft and mushy, especially at the ends by the clamps, ask your technician to look at it immediately. You could be feeling the most common cause of wear: Electrochemical Degradation (ECD).
Hose Abrasion Damage
Hose Heat Damage
Heat Damage
What is Electrochemical Degradation (ECD)?
Electrochemical Degradation of HoseECD is one of the most common causes of hose wear, but is much more difficult to diagnose because you can’t see it—the hose breaks down from the inside out. Essentially, the engine and its components are made out of different metals. The dirty antifreeze and conglomerate of different metals create an electrical charge in the coolant system as the system is running. When the charge reaches its peak, it discharges as it enters the neck of the hose and can eventually “eat” your hose, first causing the inner tube to etch and crack, which then weakens the next reinforced layer, ultimately causing the hose to have a pinhole leak or burst.
What's a car thermostat?
Car Heating and Cooling ThermostatThe car thermostat is a small, 2”-round device that sits between the engine and radiator. Its job is to block the flow of coolant to the radiator until the engine has warmed up. When the car’s engine is cold, the thermostat is completely closed. As the engine warms, the thermostat opens more and more, gradually letting in engine coolant. Once the engine is fully warmed, the thermostat is completely open, keeping the engine at its optimum, constant temperature.
How do I know that my car thermostat is going bad?
If you’re experiencing low heater output, overheating, poor fuel economy, knocking or pinging when accelerating, high idle speed, an electric cooling fan that runs continuously, or low temperature gauge reading, your thermostat could be failing. A faulty car thermostat can even cause your car to fail an emissions test.
What's a fan?
The fan also helps keep the engine at a constant temperature. Fans are controlled either by a thermostatic switch or by the engine’s computer. They automatically turn on when the temperature of the coolant rises above a certain set point, and turn off when the temperature drops below that point.
How often should I have my cooling system checked?
Have your car cooling system inspected every 12,000 miles or at the very least, every 12 months. Coolant (antifreeze) protects your engine from freezing or overheating, but over time it can degrade. It’s also extremely caustic. If left in the radiator too long, it will begin to corrode the metal and cause a leak because the additives in the coolant have broken down. It’s important to keep your engine clean by removing rust and scale, and preventing it from corrosion, wear and ECD — have your technician flush and fill the coolant per your car’s recommended schedule.

Automotive Cooling System
Hot Tips on Car Cooling Systems
  • The #1 cause of engine coolant leaks is corrosion & the #1 cause of corrosion is lack of routine car maintenance. STAY ON TOP of your recommended auto maintenance schedule. A flush and fill will renew the engine coolants additive package and help eliminate ECD in the system.
  • Even the best hose can fail without warning. Ask your technician to check your coolant hoses and other cooling system components regularly.
  • Check your car cooling system every 12,000 miles or every 12 months, whichever comes first.
  • Extreme heat in today’s engine compartments coupled with poor coolant conditions can cause your hoses, as well as your coolant system, to fail prematurely. Replace your hoses AT LEAST EVERY 4 YEARS or more often as needed.

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