7 Causes & Fixes Of Overheating Engine When Idling

By September 13, 2022Common Questions

A car may overheat when idling due to common reasons like faulty thermostat, broken water pump, defective radiator, low coolant and broken radiator fan. Most car overheating problems are caused by a faulty cooling system in the car.

I personally have gotten into a few overheating issues over the years. After many headaches and repairs, I have compiled this list of common causes for car overheating problems, so you could have it easier.

1. Faulty Thermostat

A faulty thermostat could cause car overheating issues. A thermostat is responsible for reading the temperature and controlling the flow of coolant. A faulty thermostat provides incorrect temperature reading that prevents coolant from flowing as intended and results in overheating the engine.

Fix: Replace the faulty thermostat with a new one.


2. Broken Water Pump

The water pump pumps a mixture of coolant and water into the engine components. If the water pump is not working the engine will not get enough coolant circulation which will cause overheating.

Fix: Install a new water pump.


3. A Defective Radiator

A defective radiator could cause car overheating problem if it’s a clogged radiator or a leaking radiator. Over time the sludge builds up inside the radiator. which clogs the radiator and prevents coolant from flowing properly.

A leaking radiator basically has a hole from which the coolant leaks slowly and the coolant level inside the radiator decreases. Low coolant means not enough cooling for the engine.

Fix: If your radiator is clogged then you can take it for the service to unclog the radiator. A leaking radiator also can be fixed with the help of soldering. However, if you have a very old radiator then I would recommend you get a new radiator instead of fixing the old one.


4: Low Coolant

When there is not enough coolant in the radiator it will cause overheating of the engine. Coolant flows through engine components and cools down the engine heat. The coolant travels from the radiator to the engine and the radiator uses air to cool down the hot coolant.

This circulation of fluid keeps your engine cool and prevents overheating. Low coolant means that the engine is not getting enough fluid circulation and your engine will overheat even on idle.

If you are living in a hot area where the temperature is above 40c, then you might often face this issue.

Fix: Before traveling on a longer route please make sure that your radiator has enough coolant and that there is no leakage. If the coolant level is lower than ideal add more coolant and then you are good to go. 


5: Broken Radiator Fan

When the radiator fan stops working the car engine will get overheated. There could be many reasons why the radiator fan stops working. It could be permanent damage to the fan or in some cases, the radiator fan wires don’t work properly. Since the fan is not getting electricity from the attached wire, it will stop working.

Fix: If the problem is with radiator wires then you can fix it temporarily. You can bypass the radiator fan wires in case of emergency. Bypassing the radiator fan wire will surely fix the problem temporarily.


6. Improperly Fitted Brakes Or Tires

When brake pads are not fitted properly they can cause unwanted friction on wheels. When you drive the car the engine will produce more heat and overheat because of the force on the wheels causing friction.

Fix: take your car to a workshop where a wheel specialist worker will help you in fixing the problem. 

Also Read: What happens if you don’t bed in brakes?

7: Unreliable Fuel Pump

An unreliable fuel pump means that your car engine won’t be getting the appropriate amount of fuel. Not enough fuel means that your engine will struggle during the combustion and it will overheat as the engine runs.

Fix: take your car to a garage and let professionals do their job. If the fuel pump is broken and won’t be fixed then you can simply install a new one.

When Should I Worry About My Car Overheating?

You should worry about car overheating when you see the engine temperature gauge going more than halfway through the max and it consistently increases.

Sometimes when the gauge is slightly up it’s normal. when you are around in high temperatures outside. The hot air going could heat up the engine a little bit which is completely fine.

If your car radiator has enough coolant and you have made sure that the cooling system is working fine, then you should not worry about slight overheating.

In some cases, the cooling system failure like a radiator leakage, radiator fan malfunction, or low radiator coolant can crank up the heat of your engine. If the cooling system fails only then you should immediately take action to cool down the car. You can pull over and give your car a rest for at least 30 mins.

Meanwhile, turning off the AC and turning on the heater helps in cooling down the engine faster. Open the hood so that the heat can escape from the engine bay. Check if the radiator fan is working fine, be careful while opening the radiator cap.

The heat generates a lot of pressure inside the radiator and it’s dangerous to open the radiator cap with bare hands. Use a wet piece of cloth and slowly release pressure from the radiator by opening the radiator cap. Add more coolant and your car should be fine.

How Long Can A Car Overheat Before Damage?

An overheating car can only run a couple of miles before the damage. Instead of running an overheating car, get your car towed to a garage.

As I have mentioned earlier, the overheating car won’t go too far. It will only run for a couple of miles before it reaches the maximum temperature. Then the car will stop running. The best thing to do is not take the risk of driving an overheating car.

Immediately pull over and get your car towed but if you’re in a situation where you can not get help then give your car a rest for 20-30 minutes. Drive up to a safe location and take your car to the garage asap.

How Long Can You Drive A Car That Is Overheating?

If the temperature gauge is nearly reaching max then you can only drive the car for 1-3 miles before it shutdowns. This depends on how severe the overheating is.

If the temperature gauge is slightly higher than usual then you can drive the car without worry – it’s probably due to the outside temperature. 

Things You Should Do To Avoid Overheating Increase:

  1. Turn off the AC
  2. Turn ON the heater
  3. Give your engine rest for a couple of minutes
  4. Add more coolant if the coolant level is low
  5. Avoid driving with a heavy foot

If your car is reaching maximum overheating level then immediately pull over to a safe place and give your engine rest for a solid 30 minutes. As I have mentioned above, you can follow these steps to reach your destination safely without hurting your engine.

Note: If you are in a situation where you can get help and get your car towed then go for it. It’s a better option Instead of pushing your car to its limit.

How Can I Temporarily Fix My Overheated Car?

To fix your overheated car temporarily you can take these few steps.

  1. Turn off the ac, it will take some load off from the engine and will prevent further overheating.
  2. Crank up the heater, this will also help in reducing engine heat.
  3. Find a safe place and pull over.
  4. Turn off your car and give it a rest for a minimum of 15 minutes. An overheated engine takes a solid 30 minutes to cool down.
  5. Wait for a few minutes and then open your hood but be careful cause an overheated engine makes a lot of heat and the hood surface will be hotter.
  6. Take a piece of cloth, pour some water on a cloth, and open the radiator cap slowly. Release the pressure inside the radiator and then add more coolant.
  7. Keep an eye on the temperature gauge, once the gauge starts going down you can drive the car safely to your destination.

What To Look For After Engine Overheats?

Overheating could cause damage to your engine and a few common problems after overheating are engine head gasket failure, warped cylinder heads, and Radiator damage (more details below).

1. Gasket Failure

If your car was overheating for a certain long period of time then there are higher chances of gasket failure.

If your car is producing white smoke coming out of the tailpipe and you notice coolant loss without any leakage, these are the signs of gasket failure.

A good and detailed inspection is always recommended after the engine overheats. The overheating engine damages the gasket and that results in head leakage.

The gasket works as a barrier between the engine block and the cylinder head and avoids coolant and oil from going into cylinders. A damaged gasket means that there is leakage in cylinders and your engine will fail if you continue driving the car.

2. Warped Cylinder Heads

Decreased engine power, misfiring, combustion issues, oil leakage, and excessive oil burning are the signs of warped cylinder heads.

If the engine is overheated for an extended amount of time, then there are potential chances of warped or cracked cylinder heads. Overheating will warp and expand cylinder heads and it will cause coolant leakage inside the cylinder heads.

Your combustion will disturb and your car will not work properly. Our recommendation is to take the car to a professional for a detailed inspection. Since the cylinder cracks are not visible from the outside. A detailed inspection after pulling out the engine from the car is required.

3. Radiator Damage

If your car is overheating and despite the overheating engine you kept driving the car, the coolant inside the radiator will overheat and expand. This expansion will create high pressure inside the radiator tubes and once it reaches a certain level, the radiator will blow and the coolant will be spilled all over the engine.


Q: How Can I Make My Car Engine Cool Down Faster?

It will take a solid 30 mins for a car engine to cool down but there are a few things you can do to make this process faster.

  1. Pull over and stop the car, open the hood and take advantage of the air. The airflow will reduce some heat from the engine. (be careful while opening the hood).
  2. Turn off the AC because when the AC is on, the engine has to work harder, and the harder it works the more heat will be produced.
  3. Turn on the Heater at max blow speed. This sounds strange but, trust me it works. The heater will take heat from the engine and send it inside the car. Roll down the windows to cool down the inside of your car.
  4. Add more coolant, and check if there is enough coolant available in the radiator. If the coolant level is low then add more coolant and rev your car a little bit.
  5. When you are driving around with an overheating car, keep an eye on the temperate gauge. Do not push your car any further if the temperature gauge is rising quickly. Take short breaks while driving.


Q: How Long Does It Take For A Car Engine To Cool Down?

It takes around 30-40 mins for a car engine to cool down. You can drive your car to a safe destination after giving it rest of 30 mins. While driving the car you can avoid overheating by turning off the AC. Turning on the heater will also help prevent the engine from overheating.


Q: Does Turning On The Heater Cool Down The Engine?

Turning on the heater helps the engine to cool down. The heater pulls some of the engine heat and sends it inside the car.

If your car is facing overheating issues because of cooling failure then turning on the heater is a quick way to reduce some of the engine heat. The engine heat will be sent inside the car cabin.

You might have to turn down the windows of your car to help the heat escape inside the car.


Q: Can You Pour Water On An Overheated Engine?

Do not try to pour cold water on an overheated engine or radiator. The sudden change in temperature would cause serious damage to your engine block and radiator.

You might think that the fastest way to cool down an overheated engine is to pour water on it simply. This is entirely false and it will cause damage to your car engine.

When the car has an overheated engine, the temperature of the engine is extremely hot. If you instantly pour down water on the engine block, the sudden change of temperature could cause block damage. It’s possible that your engine block could be cracked if you pour the water.

Instead of pouring water, give your engine rest for at least 20-30 mins, open the hood, check for leakage, add more coolant and drive safely to your destination.


Q: Should I Run Ac If A Car Is Overheating?

You should not be doing this at all. When the car is overheating, you must turn off the Air conditioner. Ac can cause overheating.

When the car is overheating the AC can make a big difference in controlling the overheating issue. Turning off the AC will take off some load from the engine.

When the ac is on the engine works harder to run the ac. Turning off the AC should be your first step towards cooling down the engine. The next step is to turn on the heater at full blow so that the heat from the engine will escape through the heating vents.

This would cause a slight discomfort but you can turn down the windows to maintain the heat inside.

Ifandi L.

Ifandi L.

Passionate about everything mechanical. Ifandi has been involved with motorcycles and cars since the old days - in his family's auto parts shop. Want to keep in touch? Scream "STRAIGHT PIPEEEEE" at the top of your lungs and Ifandi will show up.

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