by Bob Belding

Your vehicle’s cooling system is very important and needs regular maintenance to operate properly. Unfortunately, it is often overlooked.

The cooling system has many different jobs to do; it keeps you warm inside your vehicle in winter and it defrosts your windshield, but it also removes excess heat from the engine preventing damage to metal parts from the heat and it helps keep the engine running at its most efficient temperature no matter what the operating conditions are. It gets the engine temperature up to the right level as soon as possible after starting, while on some older model vehicles it turns the choke off when the engine is warm.

Flow of coolant through the cooling system
The cooling system of engines that use coolant or antifreeze to cool them consists of: the engine’s water jacket, a thermostat, a water pump, a radiator and radiator cap, a cooling fan (electric or belt-driven), hoses, the heater core, and usually a resevoir or overflow tank.

There are a few things that I recommend should be done yearly that will give you the maximum life out of all the components in your cooling system and prevent damage to other engine components. Replacing the thermostat and gasket once a year will ensure your vehicle’s engine is always at the proper operating temperature and the cabin area of your vehicle is always warm.

There is no point in waiting until the thermostat malfunctions because it may cause the engine to overheat or you may find it a little chilly while driving.

Replacing the thermostat and gasket on most vehicles is fairly easy. But before you begin this procedure, a word of warning: DO NOT PERFORM THIS PROCEDURE WHEN THE ENGINE IS HOT. REMOVING THE RADIATOR CAP CAN CAUSE STEAM TO SHOOT OUT AND SERIOUSLY BURN YOU.

Location of the thermostat on a 1997 Hyundai Tiburon
First, remove the bolts from the housing which is usually located on the engine at the end of the upper radiator hose. Remove the thermostat itself, but pay close attention to the way the thermostat is sitting in the housing so you install the new one the same way. Then clean the gasket surfaces.

Once the surfaces are clean apply some gasket glue to the housing surface and stick the gasket to it, install the housing back in the engine and torque the bolt down to specification. If you can’t find the torque specification ask your local dealer where you purchased the parts.

Now that the thermostat has been taken care of it is a good idea to have a look at the cooling system hoses and the clamps that keep them in place to ensure that they are in good shape. Look for signs of cracking in the hoses and for clamps that look loose or are rusting away. Any of these are signs the items should be replaced.

So you have a new thermostat and your hoses and clamps are in good shape. Must be finished now, right? …Wrong. Now is the perfect opportunity to replace the antifreeze.

At the bottom of your radiator you will notice a drain cock. It looks a bit like a tap. When the engine is cool, open the radiator cap, place a bucket under the draincock and open it. The antifreeze in your engine and radiator will drain into the bucket. Once it is finished draining close the draincock.

Do not leave the bucket of antifreeze lying around. If your neighbour’s dog finds it, you may find the dog has become a little cool and stiff too! Have it recycled (the antifreeze, not the dog) as soon as possible or at least store it in a sealed container.

Location of cooling system components.  Pictured: 1997 Hyundai Tiburon
Now its time to fill the cooling system with new antifreeze. A 50/50 mixture of water and antifreeze will give an antifreeze strength of about -35F (-30C). Depending on where you live, you may want to adjust the mixture. Once the radiator is full, and with the radiator cap still off, start the vehicle, turn on the heater and let the engine idle. Keep adding antifreeze until you notice that there are no more air bubbles coming out of the cooling system and the thermostat has opened. This should take about twenty minutes or so
and you can confirm this by checking how much heat is coming out of the heater.

Once this is complete you should check the level of antifreeze in the overflow jug, usually located to one side of the engine compartment, and fill it to the line level. Now it is time to put the radiator cap back on the top of the rad – not the old one you had taken off, but a new cap. This will compliment the job you have just done nicely! Antifreeze has corrosion inhibitors in it so replacing the antifreeze will help keep your cooling system components in good health.

Servicing the cooling system on a once a year basis is very good maintenance and can be done by a licensed technician at your local repair shop if you do not feel comfortable doing this service yourself.

One last quick reminder… NEVER REMOVE THE RADIATOR CAP WHEN THE ENGINE IS HOT. There is a lot of pressure in the cooling system at that time and REMOVING THE PRESSURE CAN CAUSE STEAM TO SHOOT OUT AND SERIOUSLY BURN YOU, and you will find nothing cool about that!

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