Car Overheating When Idle (Causes & Solutions)

An engine that is overheated is not an excellent sign for a vehicle, as it could result in costly damages. It’s typically an issue resulting from a faulty cooling system.

When you have a Car overheating when idle, what exactly does it mean?

A car overheating when idle problem could b caused by various reasons which will be discussed below.

We must first emphasize that you shut down your vehicle when you notice your car overheating when idle. Call for a tow truck and get your car taken to an auto repair center.

Inadequately addressing a Car overheating when idle could result in more damage to the car.

Before you begin, remember that certain parts can’t be checked while you’re running the engine or even right after shutting the engine off. For instance, don’t check your coolant level while the engine is still hot to avoid burning your body.

Car Overheating When Idle (Causes)

Some of the most basic things you should look for in the event that your car has a Car overheating when idle problem are:

1. Low Coolant Level

As the name implies, coolant ensures that your car stays cool. It circulates throughout the cooling system, taking excessive heat from the engine, cooling down inside the radiator, and repeating the process.

If the coolant levels are not sufficient, or if it is contaminated, this could cause you to have the Car overheating when idle issue, even more especially when you’re driving.

Here is what to do the Car overheating when the idle problem is caused by a low coolant level

  • Make sure the engine is at a cool temperature.
  • Check the coolant level and refill it if possible. A low coolant level can lead to overheating.
  • Inspect your vehicle for any form of leak and fix it.
  • Use only specific kinds of antifreeze to fill the system.

2. Trouble With the Thermostat

The thermostat of your automobile’s engine is an essential element in regulating your engine’s temperature.

When the coolant in your engine gets to a certain point, the thermostat valve opens, allowing the cooled-down liquid pumped from the radiator to flow into the engine, while the hot coolant coming from the engine takes its turn cooling off.

 If there’s an issue with the thermostat, the thermostat’s ability to regulate the temperature may be less precise, and you will experience a car overheating when idle problem.

3. Fan Belt Problems

When the radiator fan stops rotating, make sure you check the belt. A loose fan belt can cause excessive heat in the engine. When the belt appears worn out, frayed or, missing, it can cause the Car overheating when the idle problem.

4. Electric Radiator Fan Problems

Electric radiator fan problems can occur during stop-and-go traffic. if you’re stuck in traffic and it is the only instance you’ve experienced an engine that is overheated, and the gauge begins to shift back into the red after you accelerate, it is likely a faulty radiator fan.

While driving, the normal airflow cools the radiator’s coolant. When you’re driving slow or stopped in traffic, it is the fan that moves the air around that helps your coolant to be cooled.

Rectifying the electric fan problem:

  • If your fan is electrical, make sure it’s connected.
  • You can test the fan by turning on the A/C which will also cause the fan to switch on or spin.
  • The motor of the fan could be burning out, or there may be an issue with the fan switch, resistor pack, or wiring.

Why Would a Car Only Overheat at Idle?

Why Would a Car Only Overheat at Idle
Credits: Nixx Photography / Shutterstock

Understanding your vehicle’s cooling system could help you understand why you might be having a car overheating when idle problem.

The basic principle is that hot coolant gets circulated through the radiator, which is where the heat exchanges with air. The coolant is continuously moved through using the water pump, which allows your engine to operate at the right temperature.

When your car is in motion, it pushes air by the radiator, which aids in helping to draw in more heat. Assume what happens if you put your hand or even your face out the window of a vehicle moving, and you’ll be able to understand how this works.

The radiator is still functional even when the car isn’t in motion. However, it’s not as effective as when in motion. To aid the process, a fan pushes air into the radiator. Certain cars make use of a fan powered by a belt, and some use electric fans; however, the concept is the same.

In any event, it’s evident that even though your engine isn’t as efficient when it’s idle, the engine is still working on releasing the heat even when it doesn’t have air flowing over the radiator.

The car overheating when idle issue is typically caused by the fan not performing its job. However, it’s not a bad idea to examine things such as the coolant first.

Car Overheating When Idle? (Here Is What to Do)

If your vehicle is running too hot while idle, it would be a huge disaster to be stuck in traffic. Here is what to do if you have a Car Overheating When Idle problem.

1. Checking and Adding Coolant

Adding Coolant
Credits: Setta Sornnoi / Shutterstock

An engine that gets too hot could cause irreparable damage, which is why it’s crucial to ensure that your engine doesn’t become too hot.

If you notice your car overheating when idle, you’ll want to stay clear of driving in the stop-and-go conditions until you are able to fix the problem or bring it to an expert mechanic.

If you’re not stuck in traffic, there are some things you can check. But, it’s essential to allow your engine to cool off before looking under the hood.

It’s crucial to ensure that the coolant’s temperature has dropped enough for it to be depressurized before examining it.

If the hoses remain particularly hot to the surface, or they seem to be stretched when you press them, this is a warning that the removal of the radiator cap can earn you a face full of boiling antifreeze.

When it cools down, you can then take off the cap from your radiator. You are able to do so; if the coolant isn’t at the top of the fill neck, then add the proper kind of antifreeze.

It will likely state which one to use in your owner’s manual guide or under the hood.

There are instances where the coolant reservoir is an overflow bottle rather than the radiator. If your vehicle is one of these, you might be able to determine whether or not thecoolant is filled by examining the side of the bottle.

However, it is still essential to check at night when the temperature is cold. This is because coolant expands once it gets hot, and it will appear as if it’s full until it cools down.

2. Mixing Antifreeze and Water

Another thing to remember when working with coolant is the fact that it’s composed of a mix of water and antifreeze.

The reason for this is that antifreeze is excellent in preventing freezing; however, it’s not the best in transferring heat.

Therefore, by mixing it with the water, you will prevent your engine block from crashing during winter or getting overheated mid-drive.

If someone or you changed your coolant using straight antifreeze or a highly potent mix of antifreeze, it could cause an overheating issue. Thankfully the antifreeze hydrometer will only cost you ten bucks or less.

If you discover that your antifreeze solution is too powerful, removing some of it and adding straight water could aid in resolving the overheating issue.

Belt-driven Fans and Overheating Problem Solutions

Many vehicles with an engine that runs longitudinally use belt-driven fans. This simply means that fans are attached to a pulley and powered through an additional belt.

This is evident when you lift your car’s hood. You’ll see an enormous fan in between the radiator and the engine, which is attached directly to the engine.

In certain situations, the fan might be connected straight to a pulley. That means that when your engine is operating, the fan is blowing. In other situations, it will be attached to a fan clutch made to be used when it is needed.

The simplest thing to examine is your fan belt. If it’s not tight, you can tighten it to fix the issue.

When the belt appears to be brittle or missing, replacing it and tightening it can most likely fix the issue, except there’s a deeper issue such as a pulley that’s not aligned correctly.

If your vehicle has an engine with a fan clutch, then the scenario can be a bit more complex. It might appear that everything is functioning perfectly; however, if the fan clutch doesn’t engage when it should, that may be the cause why your car is overheating when idle.

Certain fan clutches are electrical; some are thermal. If you have thermal fan clutches, you should ensure that it’s connected and that the wires and connector aren’t damaged. If the connector isn’t working or the wires are damaged, this could be the reason.

Radiator Fans and Overheating Problem Solutions

Radiator Fan
Credits: Setta Sornnoi / Shutterstock

An automobile that has longitudinal engines, as well as the majority of cars with transverse engines, has electricradiator fans.

They are installed close to or on top of the radiator and are designed to turn on when the flow of air through the radiator isn’t adequate.

It’s fairly easy to determine if your radiator’s electric fans are functioning or not when you examine that your engine is getting overheated.

If your engine is overheating and the fan hasn’t turned on, it’s the issue right there. It could be that the motor in the fan is burning out or there’s no electricity reaching the fan due to some reason.

One method by which you might be able to test the performance of the radiator fan is by turning on your AC. This can cause the fan or the fans to switch on. If the fan isn’t turning on, there’s likely an issue.

The simplest way to test here is to see if the fan is connected or not. If it’s not or there are any damaged connectors or wires, it could be the cause.

You may also be having an issue with the fan switch or perhaps an issue with the on-board computer of your vehicle.

If you’re using a voltmeter and have access to the power connector of the fan, it is possible to test for power. If the fan is powered but isn’t on, changing the fan is a safe option.

Temporary Fixes for a Car That Overheats at Idle

When you’re unable to determine the issue on your own, you’ll have to get it fixed prior to your engine getting damaged. In the meantime, if you’re caught in traffic and have no exit, you might be able to reduce the temperature down for a short time.

In certain situations, the turning on of the air conditioner could force the electric fans to switch on.

This adds a load onto the engine; however, making the fans turn on could compensate for the difference.

In other situations switching on the heater can actually aid. The reason for this is that the heater’s core is a significant radiator that transfers heat to your car instead of out.

Therefore, when you switch on the heating, and you’re removing the heat through the coolant. In some instances, it might suffice to prevent your engine from overheating enough to take it to a garage.

Here is a video to see what to do when you have a car overheating when idle problem

Frequently Asked Questions about Car Overheating When Idle

Why Does My Car Overheat at Idle?

The problem of a car overheating at idle could result from an insufficient coolant level or a malfunctioning thermostat, a blocked radiator, a damaged or defective radiator pressure cap, hoses that have collapsed, and cooling fans that are not functioning as well as a damaged drive belt or water pump.

Why Does My Car Overheat When Stopped?

When the car stops, the cooling fans automatically turn on to ensure that air is flowing through the radiator. If there’s an issue with the cooling system of your vehicle that doesn’t come on when you’re stopped, the vehicle will begin to heat up until you begin moving once more.

Why Does My Car Overheat When Sitting in Traffic?

Latest automobiles come with an electronic radiator fan which is able to move water through the cooling system and then helps cool down the antifreeze inside the vehicle. When you travel at greater speeds, there’s enough airflow in the radiator to ensure that the fan isn’t needed in most cases. This is why the temperature of the engine increases when stuck in traffic.

Can a Water Pump Cause Overheat at Idle?

When the water pump inside your engine isn’t performing the job it should, then you’ll observe your vehicle overheating while driving or parked on the road. The water pump performs what you’d expect it to by pumping coolant into the system.

Why Does My Car Overheat When Idling but Not When Driving?

When your vehicle starts to overheat while idle, and the temperature gauge goes to the lower end once you start moving, it’s probably because of a malfunctioning radiator fan. But, if your vehicle is stationary, the fan on the radiator should be activated and keep the air moving across the radiator in order to cool the coolant.

What are the symptoms of a bad thermostat?

Leaks of the mounting surface
Corrosion and Rust. Surface appearance: Corrosion and rust on the surface of thermostats.
Deposit build-up
Map-controlled Thermostats.

What Are the Signs of a Clogged Radiator?

some signs of a clogged radiator are:
Leakage of coolant. Scroll down for more information.
Coolant that is thick and has a different color. You’re aware of your coolant’s original color, do you?
The water pump is damaged.
Extremely high-temperature readings on the gauge.
Bends blocked and damaged fins for radiators.

What Are the Signs of a Bad Water Pump?

Signs Your Water Pump Is Failing
Overheating; a dying or dead water pump will not circulate coolant throughout your vehicle’s engine, and as a result, the engine can overheat.
Coolant Leaks. Leaks of coolant from the pump are quite common and are a clear indication that it’s time to change your pump.
Corroded Water Pump.
Muttering Noises.

How Can You Stop the Car From Overheating? 

Your car should be parked in a shaded place.
Use window shades for your car.
Get your windows tinted.
Open the windows of your car slightly.
Turn the vents on the floor.
Make use of your fresh air settings instead of the recirculation on your air conditioner.
Examine the temperature gauge in your car.
Turn on the heater to cool the engine.

Will a Clogged Radiator Cause Overheating?

A clogged radiator can damage the cooling system in general and can cause excessive heat in the engine of your car that can cause severe physical damage to the vehicle over time.

How Do I Know if My Water Pump Is Working?

After turning off the engine, open the hood and look for the pulley for your water pump. Wearing gloves, grab the pulley and move it in a circular motion. There shouldn’t be any movement. If there is, that, along with the sound, is a sign that you might have an issue with your water pump.

Will a Blown Head Gasket Cause Overheating?

The leaks in the head gasket could be the result of an engine that is overheated. Since the head gasket is responsible for keeping coolant moving properly throughout the engine and a leak in the head gasket is often a cause for the engine to overheat.

Conclusion – Car Overheating When Idle

The problem of a car overheating at idle could result from an insufficient coolant level or a malfunctioning thermostat, a blocked radiator, a damaged or defective radiator pressure cap, hoses that have collapsed, and cooling fans that are not functioning as well as a damaged drive belt or water pump.

it is advisable that you take your car to an auto repair center to have the cooling system checked out and fixed immediately

Scott Greene is a seasoned automotive technician for over 5 years and has been deep into advanced automotive diagnostics for a couple of years. He Loves writing about Automotive Diagnostics and Repair, Trouble codes, Buyer guides for various car parts and accessories, and lots more. 

Leave a Comment