The thermostat is what keeps your car from overheating. It does this by regulating the flow of coolant through the engine block. It also helps heat your car in winter. Changing your thermostat yourself is a very simple way to save on your car's maintenance costs.

Always wait until your engine is cool before working on any part of your car's coolant system. Under normal usage, the coolant in your engine will be both pressurised and extremely hot. Removing the radiator cap or otherwise releasing the coolant can result in an explosive release of scalding hot liquid and serious burns.

You should have the tools you will need at hand before you start. In addition to the new thermostat, thermostat housing gasket, and replacement coolant, you will need a small socket wrench which fits the bolts of the thermostat housing (usually 9/16 or 11 mm), a small adjustable wrench, a small scraper or wire brush, and a two-gallon (nine-litre) bucket and a drip pan for the coolant. You will also need waterproof sealer.

To find your thermostat, trace the top hose from your radiator until you find the thermostat housing, which is shaped like a triangle and bolted down. The most common location for a thermostat in most North American vehicles is at the front of the engine. Keep in mind, however, that four-wheel drives and many Japanese and European models orient their engines differently.

Next you should drain your cooling system. Your vehicle should be level when you do so. There should be a plug at the bottom of the radiator: place your bucket under it before you remove it! Place the drip pan under the part of the engine which contains the thermostat. This will catch the coolant run-off when you remove the thermostat housing.

The key to the next steps is to remember that everything goes back on the same way that it came off. It may help to be holding the replacement thermostat ready in your spare hand while removing the old one, so as to maintain the orientation.

Move the hose out of your way. Take out the two or three bolts holding the thermostat housing in place and remove the housing. It should come loose fairly easily. If not, carefully remove any remaining gasket and sealant with the scraper until it does. Too much force can cause the housing to crack. Clean off the port and all the surfaces with the scraper to get rid of the remnants of any old sealer or gasket.

You should be able to remove the old thermostat easily. Replace it with

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