What Makes a Car Overheat?

overheated car engineCar overheating is very common, even here in the UK where the weather isn’t always great! As a leading provider of MOTs, servicing and repairs, we see first-hand the issues that vehicle owners encounter due to overheating. Understanding the causes of overheating however will help to prevent such problems and keep your vehicle on the road.

Here we offer a rundown of the common causes of overheating, and reveal what to do if your vehicle overheats.

A brief introduction to overheating

As the term suggests, car overheating occurs when the engine becomes so hot that it cannot operate effectively. Your engine will have a certain operational temperature that it is most efficient at, and once your engine temperature climbs above this, mechanical damage can occur. So how hot is too hot?

Generally operating at a sustained temperature of around 115°C is hot enough to cause damage and even stop your vehicle in its tracks. There are various tell-tale signs that go hand-in-hand with overheating, however your engine warning light is often the first indicator. The temperature gauge of your vehicle will also chart the significant rise in temperature, whilst visually, steam emitting from the engine area is another sign that your vehicle may be overheating.

The causes of overheating

There are many reasons why your car may have overheated, and inefficiencies in cooling are often the primary cause of issues. Your cooling system is integral to the successful operation of your engine. Your cooling system works to disperse heat from your engine through the circulation of coolant or antifreeze. Your vehicle’s cooling system is particularly complex, and uses a radiator, heater core, thermostat, water pump and hoses as well as the engine itself to fulfil its vital role.

Leaks within your cooling system are common reasons why your engine may be overheating. Leaks not only prevent coolant circulating but also let air into the system. The presence of air within the cooling system causes ‘airlock’ to occur, and as a result large bubbles that cannot be pushed through the system materialise. Coolant flow can be dramatically inhibited by airlock, which means heat that should be dispersed stays inside the engine. Blockages within your cooling system have a similar effect, with the lack of circulation causing the engine to overheat. Blockages are commonly caused by mineral build up and the presence of foreign objects.

Water pump failure can result in overheating. The water pump plays an essential role in every cooling system by maintaining the circulation of coolant. A failed water pump can occur due to wear and tear or breakages, with engine overheating shortly following. The coolant can often be to blame for overheating. During the winter months in particular, coolants can change in consistency due to the drop in temperature. In cooler temperatures, your coolant can become gel like causing poor circulation and even blockages. Something as simple as your coolant level being low can also cause car overheating.

What to do if overheating occurs

Having coolant to hand in case of car overheating is the golden rule, especially if your coolant is running low. If coolant isn’t accessible, water often offers a temporary fix. Your air conditioning system could be the key to limiting overheating, but it’s not turning it on that works a treat. If your car is overheating, switch off your air conditioning to prevent unnecessary strain on your engine. Switching on your car heater has also been proven to be effective, not great if the weather is warm but an engine lifesaver nonetheless. Your heating system will direct heat away from the engine when in use. If overheating persists, pull over as soon as possible, switch off your engine and seek assistance from a professional.