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The cooling system


Car overheating

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Neglect your cooling system and you could be facing serious engine failure.

Follow our simple checks to help avoid engine damage and find out about how cooling systems work.

What does the cooling system do?

In a modern engine, only around one third of the heat produced during combustion is converted into mechanical energy to drive the vehicle. The rest is dissipated mainly by the exhaust system and through the cooling system.

The cooling system removes around one third of this heat by circulating coolant through the engine. (Coolant is a mixture of water and a special liquid concentrate that helps to inhibit corrosion forming in the engine.) Heat is removed by the radiator which uses air to cool the coolant.

The other important function of the cooling system is to keep the engine operating at a constant temperature at which peak operating efficiency is achieved.

Most modern systems are pressurised to raise the boiling point of the coolant so EXTREME CAUTION should be exercised when carrying out maintenance, as serious scalding could result. DO NOT REMOVE THE RADIATOR CAP WHILE THE ENGINE/COOLING SYSTEM IS HOT.

If driving in cold conditions you may need to use anti-freeze in the cooling system. Always follow the vehicle manufacturer’s directions when using anti-freeze and coolant.

What are the main components?

The main cooling system components are:

  • Radiator
  • Radiator Cap
  • Overflow or Expansion Bottle
  • Radiator Hoses & Clamps
  • The Cooling Fan
  • The Thermostat
  • The Water Pump
  • The Water Jackets & Welsh Plugs

How can I prevent engine damage from the cooling system?

Many engine failures can be attributed to neglect of the cooling system and could be easily avoided. The following check points should help you to avoid unnecessary engine damage:

  • Check the schedule in your owners manual for changing the coolant and the correct type of coolant required. If you are considering changing the engine coolant yourself, ensure you have a workshop manual showing you the correct method.
  • Check the coolant level every week. Your owners handbook will outline the correct method.

What does it mean if I have to continually top up the coolant level?

If you are continually topping up the coolant level, take your vehicle to your mechanic as soon as possible. A simple fault may turn into a major engine repair if left unattended.

What else should I do?

Check the fan belt and tighten the hose clamps on a regular basis. Your owners handbook will indicate the frequency and method, (usually every six months or before a long trip).

Most importantly, keep your eye on the temperature gauge. Pull over when the temperature rises above the normal indicator, not when the car stars to run rough or stalls. If this occurs, it’s usually too late and an expensive engine repair may be needed.

To be able to get engines to run at peak efficiency, engine designers need to be able to control the minimum operating temperature, this is controlled by the thermostat.

The thermostat acts like a valve restricting coolant flow when the engine is cold, allowing the engine to reach operating temperature quickly. As the temperature of the engine increases so does the coolant flow.

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