The purpose of a cooling system is to stop a vehicle from overheating by maintaining a constant, correct temperature. It is important that you are quickly able to diagnose a cooling system fault to prevent damage to your engine.

Common signs of cooling system damage:

Below are some common symptoms that your vehicle’s cooling system is in need of maintenance.


The temperature gauge is reaching a high level.

It is important to regularly keep an eye on your car’s temperature gauge (if it has one). This way, you can see if the vehicle is starting to overheat. If your vehicle begins to reach a dangerous temperature level, pull over immediately and turn the vehicle off.

If your vehicle begins to reach a dangerous temperature level, pull over immediately and turn the vehicle off.


There is visible leakage under your vehicle.

If you find a puddle under your vehicle, it could be a coolant leak caused by a hole in your radiator or another component in your cooling system.

If antifreeze is leaking from your car, the puddle will be red, green or yellow. If your car does not have antifreeze, keep an eye out for puddles of water.

In this case, you should drive cautiously, pulling over as soon as possible if your car begins to overheat.


The dashboard warning lights come on.

dashboard warnings

Cooling system damage can trigger the Check Engine light in cars. If this happens, you should get the light diagnosed as soon as possible.

Some cars will also have temperature warning lights which will illuminate if the vehicle reaches a high or low temperature.


The cooling system thermostat is faulty.

The thermostat is designed to get the engine up to the correct operating temperature quickly. The thermostat will open and close to maintain a constant engine temperature. If the thermostat is stuck shut, it can cause the engine to quickly overheat as cooling system fluid cannot flow through the radiator properly.

If your car’s temperature gauge takes a long time to reach halfway, your thermostat may be stuck open (this is a common condition as the vehicle gets older). A cooling system thermostat that is stuck open will cause the engine to take a lot longer to warm up which is bad for fuel economy, performance and emissions. This will also cause your heater to take longer to warm up.


The heater isn’t working.

A vehicle’s heater requires water to work. If the heater is not putting out heat, this may be caused by little or no water in the cooling system.


Checking your cooling system:

It is easy to check your cooling system for problems. Many of these problems can be easily fixed if they are attended to quickly.

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Your engine and its components will reach very high levels of heat while the car is running. Always allow your engine to cool for a few hours before physically examining your cooling system.

Never remove the radiator cap if your vehicle is still warm. This can result in serious burns. Make sure any loose items (hair, clothing etc.) are kept away from moving parts such as the radiator fan that turns on intermittently.



Check your car’s coolant levels.

For maximum accuracy, make sure the car’s engine is cold when these tests are performed.

An easy way to diagnose whether your car is leaking is by checking your car’s coolant tank. There should be lines that indicate the maximum and minimum recommended amounts of coolant. If there is not enough, top it up to a healthy level.

Take note of how full the tank is and perform this check again in a few days time. If the levels have dropped, you probably have a coolant leak.


Flushing your cooling system.

If your car is continuing to reach high temperatures but the coolant level remains the same, it may be time to replace the coolant and flush the radiator plus associated cooling system parts.

Just like oil and other fluids, coolant (antifreeze) has a limited lifespan and needs to be periodically changed. It is recommended that you replace the coolant on a regular basis.

It is especially important to flush your cooling system if you have rust in the radiator or header tank.


Check the hoses for damage.

Find the hoses that connect the radiator to the engine. Look for any tears, bulges or holes in these hoses. It is not uncommon for a hose to collapse in on itself, restricting the water flow to the engine.

If a hose is damaged, it will need to be replaced to prevent leakages and overheating.


Check the radiator cap.

The radiator cap is often overlooked when it comes to diagnosing cooling system errors.

The purpose of a radiator cap is to pressurise the cooling system to slightly raise the boiling point of the coolant. If the cap becomes rusty, dirty or corroded, it can malfunction. This can cause a buildup of pressure and heat in your cooling system.

Alternatively, a faulty radiator cap can leak fluid, causing a loss of coolant in the system.

To change the radiator cap, simply unscrew it and replace it with a new one while the car is off and cold. To avoid serious burns, never remove the radiator cap while the car is still warm.

What to do if your car starts to overheat:

If your vehicle begins overheating, you should do the following:


1. Slow down.

Try to keep your revs as low as possible. This will reduce the strain on your engine. Pull into the left lane and turn your hazard lights on. Be prepared to stop if the temperature continues to rise.


2. Turn off AC and put your heater on full blast. 

Air conditioning may keep your car cold, but it will warm your engine up. Immediately turn the AC off if your vehicle begins to overheat.

Use the heater to transfer excess heat away from the engine, reducing its temperature.


3. Pull over and turn your car off.

If the car’s temperature continues to rise, pull over to the side of the road as soon as you can and turn the vehicle off. The engine will be very hot so do not attempt to physically examine it.


4. Arrange to have your vehicle towed.

Getting your car towed is much cheaper than an engine replacement or significant engine repair which can cost thousands of dollars. Therefore, it is important not to risk your engine’s health by letting it overheat.

In order to avoid serious (and expensive) engine damage, you should get your vehicle towed, particularly if you are far from home.


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