Skip to Content

Hot Under the Hood: Understanding Why Cars Overheat and How to Prevent It

Modern-day cars have a sophisticated cooling system with multiple heat sensors and a computer-controlled electric fan. It is designed to keep the engine running in every weather. However, overheating can still happen. Let’s learn about the causes of overheating and how to avoid them.

In this post, we’ll cover the following:

What Causes Cars To Overheat?

Car engine overheating

Overheating is a common problem that many car owners face, and it can cause serious damage to your vehicle if not addressed promptly. If you notice that your car is overheating, it’s important to stop driving it immediately and investigate the cause. Here are the top ten causes of car overheating:

1 Low Coolant

The most common cause of overheating is low coolant levels. Coolant is responsible for keeping your engine at the right temperature; if it’s running low, it may overheat. Make sure to check your coolant levels regularly and top up as needed.

2 Broken Radiator Fan

Your car’s radiator fan is responsible for cooling the engine by drawing air through the radiator. If the fan is not working correctly, the engine may overheat. Check to see if your fan works correctly; if not, replace it.

3 Thermostat Failure

The thermostat regulates the coolant flow through the engine; if it’s not working correctly, the engine may overheat. You can check the thermostat by using a thermometer to measure the temperature of the coolant as it leaves the engine. If the temperature is too high, it may be time to replace the thermostat.

4 Blocked Radiator

Over time, debris can build up in your car’s radiator, blocking the flow of coolant and causing the engine to overheat. Make sure to have your radiator flushed regularly to prevent this from happening.

5 Broken Water Pump

The water pump circulates the coolant through the engine, and if it’s not working correctly, the engine may overheat. Signs of a broken water pump include a leak or a loud noise coming from the engine.

6 Clogged Cooling System

A clogged cooling system can prevent coolant flow through the engine, causing it to overheat. Make sure to have your cooling system checked regularly and flushed if necessary.

7 Faulty Head Gasket

The head gasket seals the engine block and cylinder head, and if it fails, coolant can leak into the engine, causing it to overheat. Signs of a faulty head gasket include white smoke coming from the tailpipe or oil that looks milky or foamy.

8 Exhaust Restriction

A restricted exhaust system can cause the engine to overheat by preventing airflow through the engine. Signs of an exhaust restriction include a loss of power and an increase in engine noise.

9 Ignition Timing

If the ignition timing is off, it can cause the engine to overheat by creating excessive heat in the combustion chamber.

10 Faulty Temperature Sensor

The temperature sensor sends signals to the car’s computer, which regulates the engine’s temperature. If the temperature sensor is faulty, the engine may overheat.

Various factors can cause overheating, but regular maintenance and inspection can prevent many of them. By staying on top of these issues, you can keep your car running smoothly and avoid costly repairs down the road.

Signs of an Overheating Engine

Overheating can cause serious damage to your car, so it’s important to be aware of the signs of overheating. Here are the top three signs to look out for:

1 Temperature Gauge Reading High

The temperature gauge on your car’s dashboard shows the engine’s temperature. If the gauge is reading higher than normal or in the red zone, it clearly indicates that your car is overheating.

2 Steam or Smoke Coming from the Engine

If you notice steam or smoke coming from the engine compartment, it’s a clear sign that your car is overheating. This could be caused by a leak in the cooling system, which can cause the engine to overheat. Do not attempt to open the hood while the engine is still hot, as this could result in serious injury.

3 Strange Smells

It could be an overheating sign if you notice a sweet or burning smell coming from your car. The sweet smell could be from coolant leaking onto hot engine parts, while the burning smell could be from other components, such as the serpentine belt or electrical components getting too hot.

If you notice any of these signs, you must take immediate action to prevent further damage to your car. And next, we’ll cover what you need to do.

What You Should Do When Your Car Overheats

After learning about the cause and signs of an overheating car, it is time to understand what to do in such situations. Some of the common and easy ways to deal with engine overheat are:

1. Switch off the car air conditioner: 

Switch off aircon

As soon as your car overheats, switch off the air conditioner. This reduces the stress on the engine.

After this, turn the dial to the maximum heat. It will pull the heat away from the engine.

This may make the inside of the car hot, but that’s a small price to pay for saving your head gasket.

2. Stop your car in a safe place:

Find a safe place and shut off the car completely. Let it cool down for at least 15 minutes before investigating the cause of overheating.

3. Check the coolant level:

Monitor the coolant level and top-off if needed, but never open the coolant system when the engine is hot; it’s dangerous (more on this below). However, topping up the coolant will be useless if the coolant hose is clogged or the radiator fan is broken. Consulting a mechanic will be a smart move to deal with this situation.

4. Restart the engine:

If you can’t get your car towed to the nearest repair station, carefully start the engine and drive. Monitor the temperature gauge while you are driving. If it rises again, pull over and let it cool down.

What You Should Not Do When Your Engine Overheats

Opening coolant cap

There are various things that you should not do to worsen the situation.

1. Driving:

When your engine has overheated, avoid driving. Find a safe spot and pull over. Driving in such a condition can be pretty dangerous. Driving on risks destroying your engine.

2. Do not open the hood immediately

While your engine is overheated, wait for some time before you pop the hood to check things out. Opening the coolant cap on a hot engine will cause steam to escape and burn the skin on contact. Wait for the temperature to come down before you open it.

3. Do not ignore the problem:

Engine overheating is a dangerous issue that needs to be immediately resolved by a skilled mechanic. Do not ignore it, as it can worsen the situation.

Tips to Prevent Car Overheating

Just like you, your car hates summer heat. The temperature rise can cause damage to your car and also threaten your safety. Here are the essential tips that will help you and your car from overheating.

1. Park in the shade: 

Car parked in shade

Park in a shaded area; this helps keep your car cool and increases paintwork and plastic life. If there are no shady spots, use the sunshade to avoid the heat entering your vehicle.

2. Use window shades:

One of the most valuable accessories, window shades are a savior for keeping your car cool. These shades are placed on the glass area to prevent heat from entering the car.

3. Leave your windows open slightly: 

Car window open

When you close all the windows, it traps the hot air inside. Leaving the windows slightly open can help maintain the temperature.

If your vehicle has a sunroof, crack that open too. This will create cross-ventilation and reduce the temperature immediately.

4. Turn on the floor air vents:

Many people get in the car and turn the vents on high to get the air flowing quicker. But you are better without it. Switch on the bottom vent to let the hot air rise and exit the car. Once the car starts cooling, you can open the upper vent again.

5. Monitor the temperature gauge: 

Car temperature gauge

Make sure that the needle in the dashboard is towards the center. Pull over and let your car cool down if it points toward hot.

Sum Up

Common causes of car overheating include a malfunctioning radiator, low coolant level, faulty water pump, clogged radiator, damaged thermostat, and malfunctioning fan. Aggressive driving and overloading can also cause overheating.

Regular maintenance, checking coolant levels, replacing worn-out parts, and avoiding overloading can prevent overheating.

If a car overheats, turn off the engine, let it cool down, add coolant, and seek help from a mechanic if necessary.

About the Author

This article was created with the assistance of AI technology to aid the author, John Cunningham, who is a seasoned Red Seal-certified auto technician with more than 25 years of experience in vehicle repairs. However, please note that John Cunningham has edited the content to ensure accuracy and quality.

You may find these posts useful also: