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Avoid Engine Overheating – Understanding Cooling System





Avoid Engine Overheating by understanding the function of your cars cooling system parts. Also what preventitive maintenance you can do to avoid breakdowns.

Water Pump

Usually driven by the fan belt or the timing belt when the engine is running circulates the coolant (water) around and through the different cooling system parts and engine components.

At first start-up when the engine is cold the thermostat remains closed as this stops coolant going to the radiator so the engine can reach optimum temperature faster. After the engine has reached an optimum temperature usually 80 to 90 degrees celsius the thermostat can open and allow heated coolant to flow through the radiator. The radiator is usually located at the front of the vehicle. The radiators function is to transfer excess coolant heat to the air flowing through the cooling fins of the radiator.

What makes a car overheat – Common causes

  • Low coolant level – May indicate a leak, if the leak is not visible it maybe internal indicating a cracked engine part or blown head gasket. This allows coolant to leak into engine oil or engine oil to leak into the cooling system. Engine oil may appear milky in color. Coolant can also make its way into the engine cylinders allowing hot combustion gases to enter the cooling system. It can also make an engine hard to turn over especially on cold starts as the coolant fills the engine cylinders.
  • Blockage – If the coolant hasn’t been replaced (usually every 2 years or when the coolant becomes contaminated) it breaks down and becomes very corrosive. The cooling system can fill quickly with rust and corrosion. A build up of rust or scale can cause a blockage in the radiator cores or water jackets in the engine (mineral deposits prevent proper heat transfer).
  • Faulty Thermostat – Not opening and restricting coolant flow to radiator
  • Loose Fan belt – Drive belt slips preventing water pump to circulate coolant efficiently
  • Faulty water pump – Leaking, bearing noise or broken pump shaft are all visible or audible. It’s also common for the impeller of the water pump to become corroded and lose its ability to pump the coolant efficiently through the cooling system causing the engine to overheat at higher speeds.
  • Missing fan shroud or ducting – Reducing airflow through radiator
  • Engine fan problems – Fan clutch or electric fan problems prevent adequate air flow through the radiator.

Electric Fans

Most later model vehicles are fitted with electric fans which use a heat sensitive switch to turn the fan on to avoid engine overheating. If the engine is fitted with a Thermostatic fan clutch, the fan should slip when cold. When the engine warms, the clutch should engage. You should hear and feel air flowing through the radiator and over the engine.
Avoid Engine Overheating

What Car Owners Can Do To Avoid Engine Overheating

Keeping your cars engine cooling system clean by having it regularly flushed as per manufactures recommendation. This prevents the coolant from becoming contaminated and doing serious internal engine damage.

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