Air in Coolant System Symptoms: What Are the Implications?

Air in coolant system symptoms are easy ways of knowing if air is trapped in your coolant’s system. Air trapped in your car’s coolant system can be very dangerous because it disturbs the coolant flow and causes overheating.

What Are the Air in Coolant System Symptoms


However, spotting the symptoms and fixing them is not a complex process. This complete guide will walk you through the ways you can identify the signs of air in coolant and other essential things you need to know.

What Are the Air in Coolant System Symptoms?

The air in coolant system symptoms include a broken radiator cap, poor fuel economy, a burning smell coming from the engine bay, and loss of power. You can also notice other things like leaks from your engine. Other symptoms include the following:

– Broken Radiator Cap

A faulty radiator cap is one of the reasons why air bubbles accumulate in the coolant system. The primary function of a radiator cap is to maintain the proper pressure while keeping the coolant in the system.

Broken Radiator Cap

If the cap is not well sealed, air bubbles allow air to enter the system. The lid also keeps the coolant inside the radiator; if it is not working correctly, the coolant may leak out.

– Malfunctioning Heater

A car heater is a device that uses the engine’s heat to warm the vehicle’s interior. It works by moving coolant from the engine through a network of pipes into the heater core, which can be found under the dashboard. Several factors can prevent your heater from working correctly. The presence of air in the coolant system is one possibility. Another reason is that the system needs to be adequately bled with air before being filled.

The presence of air in the system will obstruct the coolant’s average flow and could make the heater malfunction. Another possibility is when the thermostat is not operating correctly, which will make the engine run too cold or hot and affect the heater’s function.

Lastly, there might be an issue with the heating elements. If the heating element is damaged or burnt, you must replace it.

– Radiator Hose Leak

A damaged or split radiator is a common cause of overheating and low coolant levels, and it is also responsible for the buildup of air in the cooling system. If you discover that the level of your coolant is low, top it off and pay attention to the reservoir for a few days. If you notice that there’s a drop in its level, that implies there’s a leak in your radiator hose.

You must fix or replace the broken radiator hose as soon as possible. If you cannot change it immediately, you can temporarily patch the leak with a sealant. You can get the sealant in any auto parts stores around your locality. However, if the leak is bigger, you might have to replace the engine hose.

– Overheating When Driving 

Car overheating can be a result of two major things. It can be due to aid in the system or low coolant level. If you observe any of these symptoms, stop driving and inspect your engine immediately. If the issue is with the coolant gauge, top it off and continue on your journey.

However, you must bleed the cooling system if the air is in the system. This is done by running the engine until the bubbles stop and opening the radiator cap. While doing this, keep an eye on the coolant gauge to prevent it from running dry. There can be more complicated issues like a head gasket or leak in the radiator.

Don’t wait until you knock or pack up before getting it checked out. If you wait until then, it might be too late. If you notice any one of these symptoms, you must take your vehicle to a mechanic as soon as possible. They can diagnose the problem and make the necessary repairs. Air in the cooling system is nothing to mess around with, so it’s best to fix it immediately.

How Does Air Enter a Cooling System?

Air enters a cooling system through different ways, and the most common way is when there’s a leak in the system. Coolant will easily leak if there’s a crack or hole in the radiator, allowing air to get in. This can also happen when the radiator is damaged or old. 

Another common way air gets into a cooling system is through the air that can get into a cooling system through the hoses. If holes or cracks exist in the hoses, air can get in and cause serious problems.

Lastly, the air gets into a cooling system through the water pump. The pump circulates coolant through the radiator and engine, so when the pump starts malfunctioning, air can quickly get into the system.

– How the Cooling System Works

A car cooling system absorbs heat by circulating a coolant through the engine. However, the coolant has to be cooled before it gets to the engine; this is the radiator’s function. It is essential to have as much coolant as possible because it has to absorb lots of heat without boiling, when the coolant is small, the engine is prone to overheating. When overheating gets too much, the engine will stop working, and to maximize efficiency, the cooling system must also be completely sealed off from the outside air. 

How the Cooling System Works

The radiator is found mainly in the front of the vehicle, where it can take advantage of the airflow produced by its speed. When the car isn’t moving, a fan pushes air over the radiator to cool the coolant. The water pump moves the coolant throughout the system and receives power from an engine belt. The thermostat is a valve that controls the coolant flow to the radiator to prevent the engine from overheating.

As the engine warms up, the thermostat will open to make more coolant flow to the radiator, and it closes to lessen the flow of coolant as the engine cools. The radiator cover is also essential because it keeps the cooling system’s pressure at an average and stops the coolant from boiling. Most cars have a warning signal on the dashboard whenever a car’s cooling system has an issue.

– Radiator Airlock

When an internal combustion engine’s cooling system gets blocked, it is known as a radiator airlock. As a result, the engine may overheat and become dangerous. Radiator airlock occurs because of several things like a malfunctioning thermostat, a buildup of dirt or scale in the radiator, or an issue with the pump.

Radiator airlock can also happen If the system hasn’t been used for a while and the water has evaporated, leaving a dry deposit behind. If your radiator gets blocked by an airlock, you might have to bleed to release the pressure and allow the water to flow through again.

This can be done using a screwdriver or wrench to bleed the radiator. As soon as the airlock is released, look out for any leaks in the system and fix them before refilling the system with water.

– Effects of a Malfunctioning Cooling System

Many problems can occur if your car’s cooling system stops working. Overheating is the most serious issue because it can harm an engine. Overeating causes the coolant to boil, making pressure and steam build up in the radiator. This may result in the radiator bursting and seriously damaging the engine.

Another issue that can occur if your car’s cooling system ceases to work is corrosion. Car coolant is acidic and can potentially corrode and fail metal engine components over time, resulting in total engine failures or pensive repairs. Lastly, if your car’s cooling system stops working, it’ll stress your battery more. With the ventilator running, the battery will have to work harder, and this could reduce battery life.

If you are having issues with your car’s cooling system, it is essential to get it examined by a professional mechanic as soon as possible. They will be able to tell what the problem is and how to fix it. In some cases, like when the radiator is leaking, they might be able to fix it. However, in other cases, like when the engine is damaged, they’ll advise replacing the entire cooling system instead.

How To Get Rid of Air in Coolant System?

To get rid of air in coolant system, the first step is to race to the source of the leak. When you find the leak, you can fix it using a patch or sealant. However, if the leak is from the radiator, you’ll have to remove it from the vehicle. 

After removing it, check if the fins are not bent, and if they are, use a fin comb to straighten them out. You can now put the radiator in the vehicle as soon as you fix it. If the leak is from the pump, you’ll need to remove and disassemble it. Check the seals and gaskets to check if they have any damage. 

If there are damages to the seal and gasket, you might have to replace them; then you can finally put the pump in the car and fill it with coolant. Also, if the hose leaks, you’ll need to change it as well. Start by unplugging the hose from the pump or radiator and use a pair of pliers to remove any clamps or fittings before cutting the old hose off and then replacing it with a new one.

– Avoid Coolant Leaks in Your Vehicle

There are some tips to follow to prevent coolant leaks from happening at all. The easiest method is constantly checking your cooling system for any signs of wear and damage. Additionally, make sure the hoses and clamps are secure and in good working condition.

Another method to prevent coolant leaks is to ensure your vehicle uses the correct type of coolant. Ask your mechanic or consult your owner’s manual if you don’t know the right kind of coolant for your vehicle.

Finally, follow the manufacturer’s guidelines while changing the coolant in your car. By doing so, you’ll be able to stop the corrosion and buildup that can cause leaks.

– Replace Coolant Occasionally

Most automakers advise changing the vehicle’s coolant every 30,000 miles or two years. However, replace it more frequently if you live in a hot area or drive in stop-and-go traffic. Refer to your owner’s manual for specific guidance.

Replace Coolant Occasionally

If your engine is running hot, overheating, or exhibiting any other cooling system issues, a professional should check out your coolant. They’ll be able to detect if it needs to be replaced. However, these are some of the signs that your coolant needs a replacement:

  • The temperature gauge is reading higher than usual.
  • There’s a sweet smell coming from the engine.

It’s essential to get your car checked out immediately you notice any of these signs. Ignoring the issue can cause severe engine damage.

– Bleed the Radiator

A common procedure for releasing pressure from the system and eliminating any unwanted air pockets is to bleed the radiator. This process is straightforward and requires only a few common home instruments. You must first find the bleed valve on your radiator; it is a tiny lever or knob close to the top. When you locate it, rotate it counterclockwise until it is fully open.

Afterwards, set a bowl or bucket underneath the valve to catch any leaks. The valve should then be slightly loosened using a wrench. As the air leaves the system, you should hear it hiss. Once the water starts to flow from the valve, turn the knob slowly in a clockwise direction to tighten it up once the water begins to flow from the valve. 

The valve should not be overtightened since this could harm it. Run the engine for a few minutes after starting it, and verify the temperature gauge’s accuracy and that the engine is not overheated. Finally, switch on your heating system and ensure the radiator receives appropriate water flow by turning it on.

– Bleed the Cooling System With Jack Stands

You will need to get under your vehicle using jack stands to bleed your cooling system properly. Ensure the radiator and engine are cool before using a floor jack to raise your automobile so the radiator’s neck is above the engine. At this point, block the rear wheels and secure the vehicle on each side with the jack stand. Additionally, applying the parking brake is a brilliant idea.

Like the other methods, start the engine and remove the radiator cover to get the car up to temperature. Let the engine run for a few seconds to let all the unwanted air out of your system before turning it off. Let the engine cool before adding extra coolant until you reach the right temperature level. Give the upper radiator hose another squeeze to eliminate any air bubbles that may have become trapped. 

If necessary, you can top off the coolant and take a test drive after replacing the cap. At this stage, your car should have been emptied of all the air in the lines. If none of the fixes help and the issues persist, you should visit a mechanic to identify the source of the problem. You may be dealing with a different problem altogether, or there may be a crack or break in the cooling system that allows air to enter.

How Is the Cooling System in a Car Cleaned To Prevent Air?

The cooling system in a car is cleaned to prevent air by flushing out the radiator hose, flushing the engine block, flushing the heat exchanger, and refilling the system. You can change or clean your car’s cooling system by following these easy steps.

However, you can also easily reach out to the nearest service center if the process gets too difficult.

– Preparation

Before starting your vehicle, it’s essential to let the engine cool down. Ensure you clean the expansion tank and drain the old coolant. Replace the old coolant with a new one if it is very dirty. As a result of environmental factors, dispose of liquid waste responsibly.

– Clean the Radiator Hose

Remove both the upper and lower radiator hoses from the radiator. Make sure you thoroughly clean the lower radiator from top to bottom for around two minutes with a closed radiator cover. To increase the effectiveness, introduce short bursts of air into the system.

Clean the Radiator Hose

Clean the upper radiator hose with water from top to bottom until the flowing water becomes clear and all the dirt has been thoroughly removed.

– Flush the Engine Block

The next step involves removing the radiator hose. Clean and flush the upper radiator hose using an efficient cooling circuit flushing tool until the water coming out of it is clear. Make sure that all of the deposits have been removed. Keep in mind that quick, pulsating air blows improve the efficiency of the rinsing procedure.

– Flush the Heat Exchanger

Before the water overflowing from the heat exchanger is clear, try flushing out the circuit. Your cooling system’s corrosion deposits can be removed from it by flushing the radiator, heat exchanger, and engine block. Limestone and silicone seal residue build up over the years and permanently damage the functionality of your car.

– Refill the System

The final step is reattaching the drain valve, thermostat, and hoses. Confirm that the connections between them are sound. After that, you can add the coolant recommended by your vehicle’s manufacturer to your cooling system. It is essential to use a refractometer to assess the mixing ratio.


This detailed article has described everything you need to know about your car’s cooling system and the symptoms of air in the coolant. Let’s review some of the important points we mentioned.

  • Air in coolant system symptoms helps you know if air is trapped in your coolant’s system. Air trapped in your car’s coolant system can be very dangerous.
  • The most common symptoms of air in the coolant are poor fuel economy, a burning smell coming from the engine bay, and loss of power.
  • A vehicle cooling system absorbs heat by circulating a coolant through the engine. However, the coolant has to be cooled before it gets to the engine; this is the radiator’s function.
  • Air gets into a cooling system through the water pump when there’s a leak and through the pump.
  • Most automakers advise changing the vehicle’s coolant every 30,000 miles or two years. However, replace it more frequently if you live in a hot area or drive in stop-and-go traffic.

Air in the coolant system is a major issue that can cause engine harm, so it’s important to frequently inspect your cooling system for leakage. If a leak is discovered, be sure to fix it as quickly as you can.

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