How To Tell If Air In Cooling System: The Silent Killer Of Engines

A poorly functioning coolant system can greatly damage the engine of your car. Before long, you will have a gaping hole in your pocket because you’re burnt through all your savings to repair the engine components. Therefore, you cannot disregard the importance of a running and appropriate cooling system to keep an engine operating optimally. But, how to tell if air in cooling system is messed up? Read this article to know more.

A cooling system serves many important purposes. For starters, it disperses excessive heat buildup in the engine to prevent overheating. Secondly, the engine’s operating temperature is maintained by this system.

One of the common issues with a coolant system, however, is the occasional accumulation of air inside it. As a result, the engine malfunctions badly. How to tell if air in cooling system? The signs are pretty glaring, yet some owners struggle to identify them.

• Cooling System
• Mechanism
• Bubbling Coolant
• Boiling Point
• Consequences of Air
• Reasons Behind Air Trapping
• Flushing the System
• Releasing Air
• Draining a Coolant System
• How to Bleed a Coolant System
• Draining Air with Jack Stand

Is There A Cooling System In My Car?

Regardless of the size of the car, there is a cooling system in every engine. In the primary phases of vehicle development, air-cooling was the norm in car engines. As the engine was exposed to air passing over it, the heat from it dissipated. With time, engines became more complicated and powerful, chances of overheating increased, and engineers were forced to come up with a liquid-based cooling system as the remedy.

Liquid cooling systems have become somewhat exclusive in modern-day automobile designs. Your car features a cooling system tasked with circulating coolant, otherwise known as antifreeze, across the engine, and through the radiator to disperse heat.

Working Mechanism Of A Cooling System

There are several components in a cooling system: a water pump, a heater core, a thermostat, coolant hoses, a radiator, and the engine. A cooling system carries out one of the most important functions inside the car, making it even more important to know how to tell if air in cooling system.

This is how it works:

• The water pump is equipped with an impeller that regulates the flow of the coolant. It resembles a windmill or fan and is rotated by the serpentine belt.
• The coolant moves through the coolant jacket of the engine – a complex web of channels along the engine block. The coolant absorbs the heat and moves it to the heater core outside the engine.
• There is a tiny radiator inside the vehicle designed to warm up the car’s interior – that is the heater core. A valve maintains the movement of hot coolant through the heater core. Through the hose, the coolant passes to the radiator.
• A radiator is simply a long tube bent into compact, shorter coils. When air passes by the coils it disperses the heat emitting from the coolant, decreasing its temperature. After moving through the radiator, the hose brings the cooled fluid to the water pump. This is a continuous cycle.

Why Is The Coolant In My Car Bubbling?

In most cars, the cooling system is pressurized. It relies on a closed, leak-free network of hoses to regulate the flow of coolant around the engine. When air pockets form in the sealer system, it causes a blockage which ultimately leads to overheating of the engine paired with bubbling of antifreeze.

The Boiling Points Of Antifreeze/Coolant

The boiling point of any antifreeze or coolant depends on the product’s quality itself, as well as the pressure inside the coolant system.

The point at which coolant/antifreeze boils depends on the quality of the product itself, and the pressure maintained inside the cooling system. However, in event of a leak in the system or a poor component, the pressure maintained inside the system is changed.

When that happens, the boiling point of the product falls since the pressure in the system falls. This is why a fault or leak in the car can result in overheating and boiling of coolant in the system.

How To Tell If Air In Cooling System?

There are a few symptoms that indicate there is air stuck in the cooling system of your car. Two of the most obvious signs would be your car overheating, and the heater not working properly. Let’s have a look at the details of these issues:

How To Tell If Air In Cooling System: Car Overheats While Driving

When the air gets stuck inside a cooling system, the car tends to overheat. The air bubbles inside prevent the sensors from reporting the correct temperature. When a lower temperature is shown by the sensor, neither the fan nor the cooling system turns on.

But there is another consideration too. If air bubbles are trapped inside the thermostat, it does not open till the temperature is super high. The main concept behind a cooling system is maintaining heat level and temperature inside a car by overseeing fluctuation. Inconsistent temperature spikes are what tell you about a flawed system.

How To Tell If Air In Cooling System: Heater Not Working

A nonfunctional car heater is one of the more signs of the presence of air pockets in the coolant system. When you turn the car heater on, no heat will be coming from the vents. Due to the air bubbles, the air could not be pushed out. The trapped air prevents the hot fluid from running into the heater core.

How To Tell If Air In Cooling System: Sound Of Water Gushing Inside The Dashboard

Many people complain about a weird water-gushing sound coming from the dashboard. It starts with the trapping of air inside the cooling system. When the car is started, the coolant pumps through the heater core but not before producing that intriguing gushing sound. But how do you get rid of it?

You must always make sure that the radiator is filled to the brim with coolant. Any air within the system needs to be released. For this purpose, some vehicles come with special valves but we will get to that later.

How To Tell If Air In Cooling System: Overheating After Fixing

If your car was fine before the recent visit to the repair shop, something has gone wrong. Repairs of the radiator, water pump, coolant hoses, or heater core are difficult to do perfectly. A subpar job can leave components loose, cracked, or improperly secured. In all of these cases, air can get inside the cooling system.

Consequences Of Air In The Coolant System

When the air gets stuck in the cooling system it creates a vacuum that lets atmospheric pressure forcefully revert the fluid into the system. If the tank does not have enough fluid, the cooling system gets air instead of coolant. Having the coolant level a little lower than the optimum measure isn’t the worst-case scenario, but it can make the car overheat.

Furthermore, if there is a bubble or air pocket inside the cooling system, it prevents the flow of coolant to that section. Subsequently, we ask, what is the reason behind the formation of air pockets in the cooling system.

It can be a result of bleeding and refilling antifreeze in the system. After the water pump is replaced or the cooling systems received a coolant flush (once you learn how to flush coolant system, as well as finding a good coolant system cleaner), air can enter the system. Air pockets like that can make the engine overheat, even though it seems to be filled properly.

Is Air In Cooling System Dangerous?

As simple as they seem, air bubbles can be quite hazardous over time. They trap heat inside the car engine’s cooling system and overheat the vehicle. You might go over safe operating temperatures which can cause a warped head, a blown head gasket, cracked engine block, damaged pistons or valves, bursting hoses, or a blown radiator.

Reasons Behind Air Trapping In Cooling System

There are a handful of factors that lead to the collection of air bubbles inside the coolant system or radiator. Keep reading to learn about them.

Head Gasket Leak

If you notice air bubbles in the radiator, it was caused by air coming in from a pressurized unit. Unfortunately, even a small leakage in the gasket becomes a bridge for the combustion gases. Gradually, the gasses get into the coolant system from the cylinder engine and it creates air pockets in the radiator.

A consistent stream of bubbles is a sign of a blown head gasket. The silver lining is that you can easily fix these problems by using a little heavy-duty radiator stop leak. These formulas efficiently seal small leaks as well as condition the coolant system.

Why Is Stop Leak Not Working?

Although a stop leak can form a dependable seal in multiple areas in the coolant system, there are also many scenarios where it will not work. For instance, a bad leak in the end tanks of the car’s radiator, coolant reservoir tank, water pump, or a hose leak. Leaks in these parts can only be fixed with a replacement of the component. Radiator stop leak isn’t strong enough to seal these leaks, no matter how much you use.

One other typical problem with radiator stop leak is it forming an entire seal over the radiator. Overusing stop leak gives birth to this side effect. Read all the directions on the packaging carefully to know the appropriate usage amount.

Companies differ in their usage of filler and strength material combinations, making it hard to give a universal measure. Some mixtures need pure water whereas others can be added to the coolant itself.

At best, using stop leak is a short-term solution, especially a product that is heavily reliant on fillers.

Poor Radiator Cap

Another reason behind air being stuck in the cooling system would be a bad or loose radiator cap. If the bubbles start forming when the engine is hot, you can assume there is a problem with the radiator cap. An unfit or loose radiator cap cannot maintain accurate pressurization. So, inspect the radiator cap and/or change it to resolve the issue.

The replacement cap has to be an OEM (Original equipment manufacturer) part. Alternatively, check for the ones the manufacturer recommends.

However, if you are still in doubt, try borrowing one from a friend or use an old yet functional radiator cap and run a few tests with that.

Leaking Radiator Hose

A leaking hose can also be what is causing the air to bubble out of the radiator. The broken components draw air inside the cooling tank, producing air bubbles. Technically, a leak that originally lets out coolant is also letting air in. Check for coolant dripping under your car.

If you are flushing the cooling system and radiator, make sure the engine is run for 15 minutes after the system was refilled. The pressure cap must be off.

Should You Flush The Cooling System?

In one word, yes. With time, low-grade antifreeze or coolant tends to pick up dust and debris from around the engine, slowly setting on the floor for the formation of corrosion. As a result, leaks happen and you are left paying heavy prices. Discarding the deposits restores the system, decreasing chances of corrosion and ensuring a fully operational cooling system.

How Often Should You Flush the Coolant System and Radiator?

Automakers and mechanics have conflicting opinions on how frequently one should flush the cooling system. The proper interval will be decided by a collection of factors – from the condition and age of the vehicle to the kind of driving you are habituated with, and the variety of the antifreeze in the reservoir.

Brief Overview Of Releasing Air From The Cooling System

If you are sure that there is air in the cooling system of your vehicle, you need to drain it for the car to function properly again. Through bleeding, you are essentially removing the air pockets from the system and preventing overheating. In addition, you are also warding off the many side effects of an overheated engine like warping or cracks. An engine that has been overheating for an extended period will take you almost a fortune to repair.

There are numerous ways of bleeding the air out of a cooling system. Most of it depends on the model, make, and year of the vehicle you are using. Some cars are equipped with a part called a bleeding screw or valve. This makes the whole process much easier.

A bleeder valve can be found in front or on top of the radiator. Open it up and the air inside the coolant system will drain right out. But as all cars were not created equal, every car does not have that feature. Check your owner’s manual to know if your car has one.

Alternatively, you can jack your vehicle to drain the air from inside it. In this method, the radiator is set higher than the rest of the system and it forces the air pockets to close up.

Draining A Coolant System With A Bleeder Valve/Bleeder Screw

A bleeder valve will make your life easier. Here’s how to bleed air from the cooling system if you have the luxury of using a bleeding screw.

Step 1 – Make A Solution Of Water And Antifreeze

Mix one part of water with one part antifreeze to create a solution. Pour some into the radiator up to the rim. Also, add the same mixture to the overflow tank or coolant reservoir.

Step 2 – Shut Down The Engine

Take off the radiator cap, shut down the engine, and allow the radiator to bleed out the air. The process usually takes between 15 to 20 minutes as the engine returns to the appropriate temperature and starts cycling coolant. Once the air is pushed out, there will be a significant drop in the coolant level. You will see air bubbles leaving the radiator, maybe by producing a gurgle.

Step 3 – Notice The Temperature

Keep an eye on the temperature gauge as the process moves along. It should reduce close to normal, if not entirely normal. Thanks to this process, coolant is fed to the radiator more evenly, helping the system keep the engine cool for longer.

Step 4 – Refill The Radiator

Pour coolant into the radiator as well as the coolant reservoir again. Perhaps they will be half empty as earlier it was only air filling it up fully. Ensure your car isn’t low on coolant.

Step 5 – Change The Radiator Cap

Use the cap to secure the radiator. This keeps most of the air outside the system – where it is supposed to be. By this point, the temperature gauge of the car should be back to normal. If the overheating persists, there might be a different problem in play here.

How To Bleed A Coolant System Without A Bleeding Valve

As you know how to tell if air in cooling system, you’ll be able to bleed the system with a bleeding valve. You can try out this method if there is no bleed screw in your car. For this workout, you must make sure the car is cold otherwise you may injure yourself.

Once more, prepare the distilled water and coolant mixture. Take off the radiator cap and fill it up to neck level with the coolant-water solution. Make sure you pour a little solution into the reservoir as well. In that position, restart the engine. When the car reaches the required temperature, coolant will start flowing in the tank. As the coolant flows through the system, air will be gradually purged from the system.

At this point, turn off the engine and allow it to cool. Add more coolant to fill the tank up. To make sure every bit of air has passed out of the cooling system, slightly squeeze the upper radiator hose.

Finish by replacing the radiator cap and turn on the engine to bring it up to temperature. Test drive your car to check if the temperature is maintained this time.

Draining Air Out Of A Coolant System With Jack Stands

To thoroughly drain out air from the cooling system, you have to place jack stands below your car. As always, ensure the radiator and engine are cool. Using a floor jack, lift the car to where the neck of the radiator is above the engine. Secure the car in position on each side using a jack stand and cover the rear wheels. We recommend setting the parking brake.

Similar to other methods, remove the radiator cap before starting the engine and bring the car up to the perfect temperature. Allow the engine to run for some time until the air has been removed from the cooling system. You can then turn off the engine.

After the engine has had enough time to cool down, add coolant until it reaches the proper level. Squeeze the upper radiator hose to get out any remaining air bubbles and top up the antifreeze if needed. Change the cap, bring the vehicle down, and take it for a spin.

By this point, your vehicle should be free of any air or air pockets in the system. However, if the symptoms remain and you still experience the old issues, get the vehicle to a mechanic; there are problems in that vehicle you cannot solve. Most likely you are dealing with a break or crack someplace in the cooling system that is allowing air to sneak in.

Key Things To Note

How To Tell If Air In Cooling System – Bottom Line

Having said everything, it is not uncommon for air to be stuck in the coolant system, but it surely is an issue you need to solve the moment you identify it. If the engine overheats, it causes serious damages to the rest of the car. Many drivers aren’t all that bothered by an overheated engine till the damages hand them a huge bill.

The cost of repairing valves or cylinders ranges between $3,000 to $4,000, sometimes more. That’s an unbelievable price to pay for a problem you could have fixed easily. A mechanic will charge about $40 to $50 based on your location, to flush the coolant system of your vehicle. As you can tell, the contrast is pretty stark between prevention and cure.

Since now you know how to tell if air in cooling system, you should not sit around waiting for the issue to snowball out of control. More expensive repairs will be waiting for you on the other end. Take the car to a repair shop as soon as you can, or if you have experience with repairing cars, feel free to make a DIY attempt.

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