I destroyed my first car in a remarkably careless and entirely avoidable manner.
It was 2003, I was 19, and the car was a 1986 Toyota Camry, which, until I bought it a couple of years earlier, had been meticulously cared for by an older woman who basically never drove more than 10 miles from her home.
It had less than 90,000 miles on it, and it should have lasted for years to come.
But, the car’s fate was sealed when I decided to ignore a huge trail of fluid streaming from beneath the vehicle. I noticed the liquid after finishing work one night, and there was no question it had come from my car. Instead of doing the right thing and calling AAA (something I always do now, obviously), I decided to try to make it the six or so miles to my house.
Everything was going fine, or so I thought, until the final mile, when the temperature gauge in my vehicle spiked into the red. I decided to forge ahead the short distance to my mechanic, finishing the drive with some smoke coming from beneath the hood and an ominous metal-on-metal ringing sound.
It turned out that fluid spilling from my car was engine coolant, the result of a loose hose. Had I simply had the car towed, the Camry would have been right as rain after a quick and inexpensive repair.
My decision carried more serious consequences. The engine block was cracked and the repair bill was some kind of god awful, frightening number, especially to a teenager.
With this story in mind, here is a Car 101 look at what causes a car to overheat. Hopefully some basic knowledge about how your car stays (relatively) cool will help you avoid the same kind of terrible mistakes I made.
What does a cooling system do?
A vehicle’s cooling system regulates engine temperature. A lot of what causes a car to overheat stems from internal combustion. An engine generates so much heat that it would cease to work without a cooling mechanism.
How does an engine generate heat?
The majority of cars today (not including electric vehicles) are driven by internal combustion. Combustion occurs in a combustion chamber when a mixture of fuel and air is ignited by an electric spark, which, as you can probably guess, is triggered by a spark plug.
The U.S. Department of Energy has a cool graphic demonstrating the process.
Not surprisingly, internal combustion – a controlled explosion – generates quite a bit of heat. Friction generated through the movement of three to 12 cylinders also raises the temperature.
What are the parts of a cooling system?
The most important components include a radiator, water pump, thermostat, fan, cooling reservoir and hoses and lines connecting the system.
How’s it work?
In brief, a water pump sends coolant from the radiator into the engine. The thermostat allows most coolant to return to the radiator once the engine’s reached its appropriate operating temperature between 190 and 210 degrees Fahrenheit. A small amount of coolant is bypassed at all times.
If the vehicle’s heating system is on, the thermostat will direct some of the coolant toward a heater core, which acts as a small radiator for coolant while a blower pushes warm air to the passenger compartment. That’s why your heat doesn’t work until your engine is warm.
Coolant returning to the radiator from the heater core or engine is cooled by air entering the vehicle, and a fan that pulls air over the liquid.
The process continually repeats itself.
Why do I see a lot of cars overheat in traffic?
If a cooling system is operating properly, sitting in traffic should not cause a car to overheat because the fan pulls in air to regulate coolant temperature. But, if the fan malfunctions, there is no air coming across the radiator to regulate the temperature, allowing warm coolant to return the engine, subsequently limiting its cooling ability.
What is engine coolant made of?
Your vehicle’s engine coolant should be a 50-50 mix of water and antifreeze. Antifreeze, as its name implies, prevents the water from freezing in the winter. Antifreeze also has a higher boiling point than water, raising the boiling point of water from 212 degrees to 223 degrees allowing it to sustain temperatures inside a running engine.
Does engine oil have anything to do with my car overheating?
In an indirect way, it can. Oil plays a huge role in lubricating pistons. If you car is low on oil, pistons won’t be lubricated as well, creating unnecessary friction and heat.
What happens if my engine overheats?
Nothing good. Warped cylinder heads are one possibility. If that happens, an engine can lose compression between the engine block and cylinder heads. Without a sealed gasket, proper combustion can’t occur. Another possibility is coolant entering the engine combustion chamber. If that happens, antifreeze mixture can burn up, lowering the coolant level further causing extensive overheating and damage.
But that takes awhile, right?
Nope. Serious engine damage can occur in just a few minutes of your dashboard’s red thermostat light turning on. Red engine warning lights mean stop immediately.
Do I need to get my system serviced?
You should ask to have you coolant levels checked with every oil change. You should also replace a vehicle’s coolant once every three to five years (follow manufacturers recommendation.) Antifreeze contains additives that help lubricate the water pump and prevent corrosion, though the efficiency of these additives can lessen over time.
Is there another car part or function that you are interested in learning more about? Tell us in the comments.
To learn more about car parts and how they work, visit AAA.com/Car101.
Written with contribution from AAA’s Car Doctor, John Paul.