Today we want to talk about a very important system in our cars – the cooling system. It’s one of those things that you don’t give much thought to until it fails and then you’re stranded by the side of the road.
Cooling systems fail more often than any other mechanical system – usually because of neglect. Don’t you hate it when something breaks, and you could have done something to prevent it?
The good news is that if you take care of your cooling system it can keep working for the life of your car
Here at AutoNetTV, we emphasize preventive maintenance services like replacing your coolant according to the factory schedule. But the various parts that make up the cooling system need attention too. The major components of the cooling system are the water pump, freeze plugs, the thermostat, the radiator, cooling fans, the heater core, the pressure cap, the overflow tank and the hoses.
It sounds complicated, but we don’t have to be experts – we can leave that to our service technicians. But, having an overview will help us remember to take care of our cooling systems.
Most people would be surprised to know that burning fuel in your engine produces up to 4,500 degrees of heat. And all that heat has to be dealt with. If the heat can’t be drawn off the engine, the pistons will literally weld themselves to the inside of the cylinders – then you just have to throw the engine away and get a new one. That would cost thousands of dollars.
Now the water pump is what forces the coolant through passages in the engine to absorb heat. The pump is driven by a belt that needs replacement from time to time. And the water pump will eventually wear out and need to be replaced. Spending some money on replacing the belts and water pump is much less than the cost of repairing the massive damage that can be done when an engine seizes.
There’s another little part of the coolant system that protects the engine. It’s called a freeze plug. If you remember from high school chemistry, water expands when it freezes. In very cold areas, the coolant can actually freeze when the vehicle is left sitting.
It is hard to believe, but the expanding frozen coolant can actually crack the engine block. The freeze plugs fit into the engine block. They fit tight enough to withstand the pressure of a running engine, but can expand or pop out if the coolant freezes. These little things save a lot of engine blocks.
That brings up a good point. An engine has to work in all kinds of temperatures – extremely hot as well as very cold. How does the cooling system adapt to external temperatures as well as varying operating conditions?
Well, it’s much like the way you keep your house at a comfortable temperature all year round – with a thermostat. The thermostat in your car controls how much coolant flows through your engine. When the engine is cold, it restricts coolant flow until the engine comes up to an efficient operating temperature. Then it starts opening up to move more coolant to keep the temperature within a specified range.
The thermostat needs to be replaced from time to time as well. It’s easy to diagnose a failed thermostat and is fairly inexpensive to replace.
Now we’ve been talking about all this heat we’ve got to get rid of, but haven’t really talked about where it goes. That’s where the radiator comes in. The hot coolant passes through the radiator. Air flows past the cooling fins and cools the coolant.
The radiator has two tanks that hold coolant: sometimes one the top and bottom or one on either side. If you have an automatic transmission, one of the tanks will also contain a second tank that cools the transmission fluid. Large SUV’s and trucks often have a separate transmission cooler.
So when you drive, the air is forced past the radiator. But driving doesn’t produce enough air flow. So the radiator has cooling fans that force fresh air over the radiator. These fans may be powered by a belt or by electric motors.
Now, you also have something called a heater core. The heater core is like a mini radiator. A small fan blows air over the heater core and into the passenger compartment of your vehicle. That’s how you warm your car when it’s cold out.
Next is the radiator cap. With most newer cars, you never remove the radiator cap, except to replace it. You add coolant through the overflow tank. The radiator cap is also called a pressure cap, because its job is to maintain pressure in the cooling system.
High pressure raises the boiling point of the coolant, so it cools more effectively even in very demanding conditions. That is why you need to replace the cap from time to time. They recommend changing it out every time you replace your coolant.
Coming back to the overflow tank, it is needed because when the coolant gets hot it expands and the overflow holds the extra volume. The tank helps maintain the proper level of coolant and keeps air out of the system. You should never open the radiator cap or over flow tank when the engine is hot. This could lead to serious burns.
What else do we need to do to keep our cooling systems working well? Well, there are the hoses that hook all of these pieces together. They’re obviously very tough to deal with the pressure and high temperatures. But they do get worn. Sometimes they get spongy from the heat.
Sometimes they lose their connection to the radiator, water pump, etc. It’s a great idea to have your service center inspect your hoses at least once a year and replace them, if needed, before they break.