What Causes a Car to Overheat?
We’ve seen it in the movies and on the side of the highway—a hood up and steam everywhere. But why do cars overheat?
Written by Andrew Koole
Reviewed by Kathleen Flear
Table of Contents
- First off, your car’s thermostat
- Your car’s water pump
- Your coolant
- Your radiator
- Lastly, your cooling fan
- Is mechanical breakdown insurance worth it?
Load full table of contents
Your car runs on explosions. Little, compressed fires light in the cylinders, pushing the pistons into rotation, propelling your car forward. All that heat needs to be cooled down throughout the process, and your car has a system for that too, but sometimes it breaks down.
If you’re paying attention, you’ll notice the needle on the gauge on your control panel start to rise. If you’re not, you’ll end up on the side of the road with steam billowing out of your hood. Not a good look.
A number of parts work together to
cool down
your car’s engine, and things can go wrong with each one of them. Knowing how they work might not help you avoid overheating, but it at least protects you at the repair shop
.First off, your car’s thermostat
Just like your house, your car has a thermostat to control the temperature of the engine. Because of the explosions mentioned in the intro, the main goal of the thermostat is to control the flow of coolant to the radiator, which transfers the engine heat into the air.
If your thermostat gets stuck and doesn’t open, your car’s engine can quickly overheat. If you regularly check your coolant levels and still run into an overheating problem, this could be the cause.
In modern cars, the temperature provided by the thermostat is measured by an Engine Coolant Temperature (ECT) sensor. If the sensor fails, you could also be in trouble.
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Your car’s water pump
Now don’t get worked up just yet. You’re not forgetting to put water in your car. Your water pump actually pumps coolant—antifreeze—to your radiator. It’s what your thermostat controls.
The water pump is driven by a belt connected to your engine’s crankshaft (the backbone of your engine). Its housing also contains a fan-like contraption called an impeller. If the pump, belt, or impeller fails, your car will overheat.
Your coolant
MORE: 3 Car Repair Issues You Can Fix Yourself—and 9 You Shouldn't
When you buy the fluid you use for your car’s coolant, it’s called antifreeze.
How Stuff Works
says antifreeze is actually a mixture of water and ethylene glycol. It can hold a lot of heat, like water, but the right mixture can stay liquid until it reaches -67 F. Your coolant travels through hoses to your engine, your pump, and into your radiator before starting the cycle all over again.
Leaks
can start at any point in the system, and if they do, they can cause your engine to overheat.Your radiator
You may hear the term “coolant” and think that it’s what drops the temperature of your car, but it’s actually the radiator that does the work. The coolant simply collects the heat from the engine.
The radiator takes the hot coolant and transfers that heat into the air using a fan before sending the coolant back to the engine.
Any blockages in the radiator, whether to the flow of the coolant or the transfer of the air to the fan, can cause your car to overheat. Any problems with the fan can do the same.
Lastly, your cooling fan
On top of all these parts working to cool off your engine, the air coming in through your grill while you drive also helps bring the temperature of your engine down. But when your engine is on while you’re not moving, your engine relies on a fan to produce that airflow.
If something goes wrong with that fan, your car could overheat, especially if you’re sitting idle or crawling through bumper-to-bumper traffic for long periods of time.
Is mechanical breakdown insurance worth it?
While liability
car insurance
is required in all but two states, mechanical breakdown
insurance is optional. To decide whether or not to buy mechanical breakdown insurance, you need to weigh the value of your vehicle to the cost of the coverage. You also need to know if you have an extended warranty on your car and what it covers if you do.If you’re shopping for car insurance,
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