Few things are more alarming than seeing your temperature gauge spike or steam rising from under the bonnet. Engine overheating is a serious issue that can lead to costly repairs if not addressed quickly. Whether your car is overheating in traffic, while idling, or even when the coolant is full, understanding the causes for overheating engines can help you act fast and prevent long-term damage.
In this guide, we’ll explore the most common car overheating causes, how to spot the warning signs, and what to do if your car has coolant but is overheating. We’ll also share tips on prevention and maintenance to keep your engine running cool.
There are several reasons for car overheating, and most relate to the cooling system failing to regulate engine temperature. Here are the most common culprits:
Coolant Issues
Coolant (or antifreeze) absorbs heat from the engine and dissipates it through the radiator. If your car is low on coolant, or the coolant is old and ineffective, the engine can quickly overheat. Even if the coolant is full, a blockage or air pocket in the system can prevent proper circulation.
Thermostat Failure
The thermostat regulates coolant flow based on engine temperature. If it gets stuck closed, coolant won’t reach the radiator, causing the engine to overheat. This is a common issue in overheating cars, especially those that overheat while idling or in traffic.
Radiator Problems
A damaged or clogged radiator can’t cool the engine effectively. Leaks, corrosion, or broken fans can all reduce performance. If your car overheats in traffic, it may be due to poor airflow through the radiator.
Water Pump Failure
The water pump circulates coolant throughout the engine. If it fails, coolant won’t move, and the engine will overheat. This can happen suddenly and often leads to engine overheating at idle or during low-speed driving.
Head Gasket Issues
A blown head gasket can allow coolant to leak into the engine or exhaust, causing overheating and other serious problems. If you notice smoke coming from the engine but not overheating on the gauge, this could be a sign of a head gasket failure.
Knowing how to tell if your car is overheating can help you act before serious damage occurs. Common signs include:
- Temperature gauge rising into the red zone
- Steam or smoke from under the bonnet
- Strange smells (sweet from coolant or burnt from oil)
- Loss of engine power or knocking sounds
- Warning lights on the dashboard
If you’re wondering, how do I know if my car is overheating, keep an eye on the temperature gauge and listen for unusual noises. If your car AC stops working at the same time, it could be a symptom of engine overheating.
If your car is overheating while idling or driving, follow these steps:
1. Pull over safely and turn off the engine.
2. Wait for the engine to cool before opening the bonnet—this can take 30 minutes or more.
3. Check coolant levels in the reservoir (not the radiator cap while hot).
4. Look for leaks or broken hoses.
5. Call for assistance if you’re unsure or the problem persists.
Driving with an overheating engine can cause severe damage, including warped cylinder heads and engine failure. If your car overheats but coolant is full, it’s best to have the system professionally inspected.
Preventing car overheating starts with regular maintenance. Here’s how to reduce your risk:
- Check coolant levels monthly and top up with the correct mix
- Flush the cooling system every 2–5 years, depending on your vehicle
- Inspect hoses and belts for wear and leaks
- Replace the thermostat if it shows signs of sticking
- Ensure radiator fans are working properly
If your car overheats in traffic or only while idling, it may be time for a deeper inspection. These symptoms often point to airflow or circulation issues.
Engine overheating is more than just an inconvenience; it’s a warning sign that something’s wrong under the bonnet. Whether it’s a car overheating while idling, or a sudden spike in temperature, acting quickly can save you from expensive repairs.
At Eurorepar, we offer expert diagnostics and repairs for all car overheating causes, from thermostat failures to radiator leaks. If you’re asking yourself, “Why is my car overheating?” let our technicians help you find the answer. So why not book a service today.
