Car Overheats When Idling

You don’t want to get in your car in the morning for the commute and see the temperature gauge needle keep rising. A car getting overheated while driving at high speeds is a common occurrence, …

car overheats when idle

You don’t want to get in your car in the morning for the commute and see the temperature gauge needle keep rising. A car getting overheated while driving at high speeds is a common occurrence, but if your car overheats when idling, something could be seriously wrong.

A car has a complex system of different parts running under the hood, and with so much heat generated during the combustion process, it needs a cooling system to maintain the optimal temperature. The car’s radiator, water pump, and coolant are the main parts that work tirelessly to maintain the engine’s temperature.

If you’ve noticed that your car overheats even while idling, there could be different reasons behind that. Let’s go through some of the most common reasons your car overheats when idling, and what should you do if it happens. So keep reading and prepare yourself if you come across such an emergency.

What are 10 Common Causes of Car Overheating When Idling

If you notice smoke coming from under your car’s hood or a temperature warning sign on the dashboard when idling, it could be due to one of the following reasons;

1- Faulty Thermostat Valve

The thermostat valve in the engine ensures a smooth flow of coolant and acts as a pathway that regulates the movement. If it remains closed or stuck halfway due to any problem, it can disrupt the normal flow of coolant and cause the engine to overheat.

This can cause your car to overheat, but only after it has idled for a few minutes or you’ve stopped after driving for some time.

2- Low Level of Coolant

Coolant is the sole thing keeping the engine temperature in check and it prevents both overheating and freezing. If the coolant level is low due to a leak or excessive usage over time, the cooling system won’t be able to regulate the engine temperature, and it is bound to overheat, whether it’s running or idling.

3- Clogged Radiator

A radiator is a rugged component of your car’s engine and it keeps running for years without any special maintenance. If the valves or passages in the radiator get clogged due to the accumulation of contaminants, the flow of coolant gets disturbed, to the extent that it may choke the cooling system completely.


If your car is getting overheated when idling, a clogged radiator might be very much the culprit behind it.

4 –Leak in the Cooling System

A leak in the cooling system, be it in the pipes, hoses, or seals, can lead to different problems. It can cause the wastage of coolant, as well as the entry of air into the system, which is supposed to be sealed and pressurised.

A leaking cooling system is also a common cause of your car overheating when idling, and you could easily check it by taking a look under your car for a pool of liquid after parking.

5- Faulty Cooling Fan

It is the only thing keeping your engine at a normal temperature when idling. When a car is moving, the air drag keeps the coolant temperature at optimal but when you’ve stopped a signal or idling your car, the radiator fan keeps the temperature of the coolant low.

If it is damaged or has loose wiring, then it won’t work properly and your car would definitely heat up when idling.

6- Damaged Head Gasket

This important part, which forms a seal between the cylinder head and engine block, makes sure that the engine oil and coolant do not mix.

If the head gasket is damaged or has leaks, both these fluids will get mixed and the engine will definitely get overheated due to increased friction and a cocktail for a coolant flowing to every part of the engine. This is a serious problem and must be addressed as a priority.

7- Low Engine Oil Level

The main purpose of the engine oil is to lubricate the moving parts inside the engine so that the friction is kept minimal and the temperature is kept under control.

A low level of engine oil leads to metal parts rubbing against each other, increasing the temperature of the engine above normal. This coupled with the combustion process can play havoc with your car’s engine temperature.

8- Broken Water Pump

The water pump is the main part that propels the coolant from the container to all parts of the engine. If the water pump is clogged or broken, the coolant will not flow through the pipes and hoses, and it will remain stagnant for hours.

This could cause your car to overheat when idling, while everything might seem apparently ok.

9- Over Revving

This is not such a common cause but it happens due to negligence or mischief of the driver. If you keep revving beyond the redline, it could cause serious damage to the engine and the first sign of that would be your car overheating, even while idling.

10- Air in the System

If there’s a leak in the cooling system or the radiator cap is not tightened properly, air could get into the system which is supposed to be pressurised. This leads to an abnormal flow of coolant through the system and bubbles or blockades which can prove detrimental to the engine.

This is also one of the possible reasons your car overheats when idling, and is tricky to diagnose.

Other Similar Problems:
Car Overheating Then Going Back to Normal
Car still making noise after engine turned off
Car Temperature Gauge Goes Up and Down While Driving

What to do When the Car Overheats When Idling?

If your car gets overheated while idling, here’s what you should do;

1. If you haven’t started your journey yet, it is better not to move and try to diagnose the issue.

2. If you’re already out on the road and this occurs while taking a short coffee break or at a red light, it’s better to park safely somewhere on the roadside, away from the moving traffic.

3. Turn off your car and let the temperature get to normal on its own.

4. Then try to look for the possible causes, it might be the broken cooling fan, a leak in the radiator, low oil or coolant.

5. Never open the radiator cap when the car is hot, it could burn you and the people standing nearby.

6. If you cannot locate the problem, do not panic. Better call the emergency services and a tow truck to get your car to a nearby workshop.

7. No matter what, do not try to drive your car if the problem is not diagnosed and fixed yet.

8. Always keep a bottle of compatible coolant and engine oil in the trunk, so if the problem is a low fluid level, you could easily top-up and be on your way.

Final Thought

The cooling system in your car is made up of numerous parts. Each time one of these parts fails, the system as a whole is put in danger, causing your engine to overheat when it is idling.

There are methods for locating the engine cooling system problem. Once you’ve identified the problematic part, you must either fix it manually or have a professional fix it for you.

There are many possible risks involved with operating an engine that is overheating. When you drive with an overheated engine, you run the danger of hurting yourself. It is also inevitable that the engine would sustain irreparable damage. As a result, until the problem is rectified, you shouldn’t drive if your engine overheats while idling.