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Checking your coolant and cooling fan

Engine temperature maintenance

Most modern cars have a sealed cooling system so they shouldn’t need any topping up – unless, of course, they’ve sprung a leak.

Give your engine coolant and your cooling fan a check every couple of weeks so you can spot any problems early. It’ll only take a few seconds and could save you a lot of money and hassle.

How to check your coolant

  • It's essential to correctly identify the expansion tank – check the vehicle handbook for the location of the coolant filler cap, and follow any vehicle-specific advice given (adding antifreeze to the screen wash, brake fluid or power steering reservoir would be a very bad idea.)
  • The coolant should be between the min/max marks on the side of the expansion tank
  • Check any hoses that you can see at the same time; wet or white staining is a sign of possible problems to come
  • If the coolant needs topping up, don't remove the filler cap unless the engine is cold – you could be scalded by a sudden release of pressurised hot water
  • Make sure you use the right sort of antifreeze – the different types don't mix well
  • Antifreeze doesn't just protect your engine in winter. It helps stop corrosion and scale build-up all year round
  • It's not normal for the coolant level to drop; if you see that it has, get a garage to take a look

Engine coolantHow to check your cooling fan

When your car's moving, air flows through the radiator to keep your engine's temperature 'normal', but if you stop – in a summer traffic jam for example – your engine has to rely on a thermostatically controlled electric cooling fan to force air through the radiator.

It’s important to check regularly that the fan and temperature sensor are working. Here's how:

  • Set the car heater to cold
  • Run the car until the engine reaches normal temperature
  • Allow the engine to idle for around five minutes
  • Watch your temperature gauge – don't allow the car to overheat

Cooling fans should cut in automatically. If they don’t there may be a fault with the fan temperature sensor, the wiring or the fan itself.

Ask your local garage to give it the once over.

Here's a step by step guide showing how to check your cooling fan

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