Symptoms of Air in Coolant System (Don’t Ignore These SIGNS)

The car cooling system is an important part of the car. It helps to keep the engine cool and prevents overheating. The cooling system consists of a radiator, a water pump, a thermostat, and a fan.

The radiator is made of metal and has fins that help to dissipate the heat from the engine. The water pump circulates the coolant through the radiator and the engine. The thermostat regulates the flow of coolant through the radiator so that the engine does not overheat. The fan helps to circulate air through the radiator so that the coolant can do its job more effectively.

The cooling system is important because it helps to keep your engine at a safe operating temperature. If your engine gets too hot, it can damage parts or even cause a fire. The cooling system also helps to protect your car from rust and corrosion.

It reaches a point when your car’s cooling system gets air locked, and this can result in a series of problems such as the engine overheating or getting damaged.

Some of the symptoms of air in the coolant system include:

  • Overheating when cruising on normal speeds.
  • The heater is not functioning as required.
  • Reduced engine performance
  • Radiator leaking and car losing coolant quickly.
  • An increase in fuel consumption

How car Coolant System works

A coolant system is a vital part of any car, and it is responsible for keeping the engine at the correct temperature. The coolant system circulates a mixture of water and antifreeze around the engine to absorb heat, and then takes this heat away from the engine to keep it running at its optimal temperature.

The system has several components, including the radiator, cooling fans, thermostat, water pump, and hoses. These all work together to ensure that the engine stays at the correct temperature, and they need to be in good working order for the system to function correctly.

What is Radiator Airlock?

Radiator airlock is a condition that can occur when there is a blockage in the cooling system of an internal combustion engine.

This can cause the engine to overheat and may lead to serious damage. Radiator airlock can be caused by several things, including a buildup of debris or scale in the radiator, a faulty thermostat, or a problem with the water pump.

The airlock can also occur if the system has not been used for a while and the water has evaporated, leaving behind a dry deposit.

If your radiator becomes blocked by an airlock, it will need to be bled in order to release the pressure and allow the water to flow through again.

This can be done by bleeding the radiator using a wrench or screwdriver. Once the airlock has been released, you should check for any leaks in the system and repair them before refilling the system with water.

Symptoms of Air in Coolant System

1.  Overheating During Normal Driving

When your car overheats, it’s generally due to one of two things: either the coolant level is low, or there’s air in the system. If you notice either of these symptoms while driving, pull over and check your engine as soon as possible.

If the coolant level is low, simply top it off and continue on your way. However, if there’s air in the system, you’ll need to bleed the cooling system.

This can be done by opening the radiator cap and running the engine until the bubbles stop. Be sure to keep an eye on the coolant level while doing this, as you don’t want it to run dry.

If your car overheats frequently, or if you can’t seem to get the air out of the system, it’s time to take it to a mechanic.

There could be a more serious problem, such as a leak in the radiator or head gasket. Don’t wait until your engine seizes up completely before getting it checked out – by then, it will be too late.

2. Heater Not Properly Functioning

A car heater is a device that uses the heat from the engine to warm the interior of the vehicle. It works by circulating coolant from the engine through a series of pipes and into a heater core, which is located under the dashboard.

The heater core is similar to a radiator and contains fins that help to dissipate the heat. The warmed coolant then flows back into the engine, where it can be used to help keep the engine warm.

There are a few things that can cause your heater not to function correctly. One possibility is that there is air in the coolant system. This can happen if the system is not properly bled of air when it is filled.

If there is air in the system, it will prevent the coolant from flowing properly and may cause the heater not to work correctly. Another possibility is that the thermostat is not working properly.

This can cause the engine to run too cold or too hot, which can also affect the heater’s operation.

Finally, there may be a problem with the heating element itself. If it has burned out or become damaged, it will need to be replaced.

3. Faulty Radiator Cap

One of the causes of an air bubble in the coolant system is a faulty radiator cap. A radiator cap is designed to keep the coolant in the system and also maintain the correct pressure.

If the radiator cap is not sealing properly, then it can allow air to enter the system, which will cause an air bubble. The cap is also responsible for keeping the coolant in the radiator, and if it is not functioning correctly, the coolant can leak out.

4.  Leaking Radiator Hose

A split or otherwise damaged radiator hose is a common cause of low coolant levels, and thus overheating.

It can also cause air buildup in the cooling system. If you notice your coolant level is low and top it off, pay close attention to the reservoir over the next few days. If the level drops again, you likely have a leak in a radiator hose.

You’ll need to replace the damaged hose as soon as possible. In the meantime, you can try to temporarily patch the leak with a sealant designed for radiator hoses, available at any auto parts store.

You should replace the hose: If the leak is bigger, you’ll need to replace the entire hose.

How to Bleed the Radiator

Bleeding the radiator is a common way to relieve pressure in the system and get rid of any unwanted air pockets. This process is relatively simple, and only requires a few household tools.

First, you’ll need to locate the bleed valve on your radiator. It is a small knob or lever near the top of the radiator. Once you’ve found it, turn it counterclockwise until it’s completely open.

Next, place a bowl or bucket underneath the valve to catch any water that may drip out. Then, use a wrench and loosen the valve slightly. You should hear a hissing sound as the air escapes from the system.

Once the water starts flowing from the valve, slowly turn the knob clockwise until it’s tight again. Be sure not to over-tighten the valve, as this can damage it.

Start the engine and let it run for a few minutes. Check the temperature gauge to ensure it’s working properly and that the engine isn’t overheating.

Finally, turn on your heating system and check the radiator to ensure the water is flowing through it properly.


If you notice any symptoms of air in the cooling system, it’s always important to have the problem fixed as soon as possible.

As I have already mentioned, any problem in the cooling system will not only result to overheating but can also cause other engine-related issues.

If you are unsure of the possible causes of the problem, it’s important to have it diagnosed by a qualified mechanic.

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