Why Is My Car Overheating?

By Victor Ivan Coll

Updated April 24th, 2024

You probably know that the engine in your car gets hot. Too hot to touch. But do you know that’s actually a good thing? Your engine is designed to operate within a specific heat range — usually somewhere near 200 degrees Fahrenheit. The heat is normal and necessary.

Too much heat, on the other hand, is not a good thing. A warning light or gauge on the dashboard, steam pouring out from under the hood, liquid pooling on the ground under the engine, or a sweet, maple syrup smell coming from the car are all signs that the the engine may be too hot. And overheating can cause serious engine damage leading to thousands of dollars in repair costs.

So, what causes a car to overheat? What kind of damage can happen if it does? How can you prevent the problem from occurring in the first place? And what do you do if it happens to you?

Why is my engine overheating?

Your car is equipped with a cooling system designed to regulate engine temperature typically between 195–220 degrees. The system is made up of many components and uses a liquid coolant (also known as “antifreeze”) to carry some of the heat out of the engine so it can be released into the air. If a problem arises at any point in the cooling system, overheating can occur.

For instance, if the coolant is unable to flow freely through the system, the heat will be trapped inside the engine and the engine temperature will rise. This restricted coolant flow can happen in a number of ways. The water pump forces coolant through the engine and to the radiator. If the water pump is faulty, the coolant will be unable to move. Likewise, if the thermostat (the valve that opens and closes to regulate temperature) is defective, the coolant may not flow. A clogged radiator or heater core — or a collapsed coolant hose — can also restrict the movement of the coolant through the cooling system.

Besides blocked coolant, another cause of engine overheating is restricted air flow. Heated coolant leaves the engine and travels to the radiator, where the heat is transferred to tiny aluminum fins through which air passes. When the air travels past the fins, the heat goes with it. If the fins in the radiator are clogged with dirt and debris, the air cannot pass. A cooling fan is tasked with increasing this air flow. If the fan does not work, an insufficient amount of air passes through the radiator fins. In either case, clogged cooling fins or a defective cooling fan, overheating can result.

Another issue is leaking coolant. In order for the coolant to do its job, it must completely fill the cooling system. When it leaks out, it is replaced by air. Any air present in the system presents problems, including air bubbles that block the flow of coolant. Coolant leaks can be external (from the radiator, hoses, or engine seals) or they can be internal (resulting from a deteriorated intake manifold gasket, head gasket, or warped/cracked cylinder head). Sometimes leaks are apparent outside the vehicle (like a pool of liquid on the ground) and sometimes they are less-obvious, especially if the leak is internal.

What happens if the engine overheats?

No matter what the cause, the consequences can be severe if an engine is allowed to overheat for too long. And it really does not take very long for damage to occur. Engine overheating can lead to:

• Decreased engine compression and a lack of power
• Stalling
• Burst radiator hose
• Fire in the engine compartment
• Warped cylinder head or blown head gasket
• Damage to the valves, pistons, or cylinders

Preventative maintenance can help reduce the chances of overheating. Monitor engine temperatures and do not ignore dashboard warning lights. Have the cooling system inspected periodically to make sure the cooling fan is operational and the hoses are in good shape. Keep your eyes open for any fluid leaks. Have the cooling system flushed every 30–60k miles. And have the thermostat replaced any time the cooling system is serviced.

What do I do if my car overheats?

If you do notice any of the symptoms of an overheating engine while you are driving, follow these steps to keep yourself and your passengers safe and your engine free from damage.

1. Turn on the heater to help release some of the engine heat into the passenger compartment.
2. Pull the vehicle over as soon as you can — safely.
3. Turn the engine off.
4. Get out of the car and open the hood. This will allow more heat to escape. But do not do this if steam is pouring out from under the hood.
5. Have the vehicle towed to a trusted repair shop.

Note: Do not remove the radiator cap when the engine is hot! Steam from inside the radiator can cause severe scalding and burns. If you need to remove the cap (to add coolant), wait until the radiator hose is cool to the touch — at least a half hour — and cover the cap with a towel.

Engine overheating does not happen often. But if it does happen, avoid damage to your engine by following these steps. And get professional assistance as soon as possible. Better yet, have your cooling system inspected as part of routine maintenance to avoid engine overheating altogether.

Victor Ivan Coll | Victor Coll | Author: Victor Ivan Coll | Copyright 2023

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