It’s been touted as, an engine’s silent killer.
A coolant system that isn’t functioning properly can severely damage your engine.
At the very least it certainly can lead to the malfunctioning of other components. And when those parts go bad, you’ll need to replace them if you want to keep your automobile running smoothly.
Like anything else, engine cooling issues can get misdiagnosed. So, how can you tell if your cooling system is operating optimally?
In this article we look at some of the most common symptoms of air in the cooling system.
The Presence of Air Effects a Cooling System’s Ability to Work Normally
Understanding how the cooling system works in an automobile can help you form an idea of what’s going on with your car before taking it to a mechanic.
The main purpose of a cooling system is to keep the engine from overheating. An engine’s cooling system is sealed and usually pressurized.
It maintains operating temperature by circulating coolant throughout the engine to absorb heat.
But the presence of air compromises the system.
Several components makeup the cooling system of an internal combustion engine:
- The thermostat is a valve that regulates the flow of coolant to the radiator. When it senses that the engine is getting too hot, the thermostat opens to allow coolant to circulate the engine.
- The radiator sits in front of an engine. It’s made up of tubes bent into shorter coils that are designed to carry coolant to dissipate heat.
- Connected to the radiator are coolant hoses which carry coolant to the water pump.
- The water pump is usually driven by the serpentine belt. It has an impeller in the shape of a windmill used to circulate coolant around an engine.
- And finally, the heater core is located outside the engine. Coolant absorbs heat as it moves through a complex array of channels along the engine to wind up at the heater core. (We’ll talk more about the importance of the heater core as you keep reading.)
But air inside this system causes disruption to the flow of coolant leading to many issues with your car.
Even a small amount of air will prevent proper circulation of coolant.
Below are symptoms of air in the cooling system:
Overheating is the Most Obvious Symptom That There Could Be Air in the Cooling System
Overheating is a sure-fire sign that the cooling system isn’t cooling the engine properly.
Pockets of air obstruct the flow of coolant to the engine, which can lead to overheating.
You see this a lot in movies and tv shows: a character is tooling down a highway when all of a sudden smoke comes pouring out from under the hood.
As impressive as it looks this just vapor coming from an overheated cooling system.
Overheating happens when one of the coolant passages in the engine becomes clogged and starts to leak.
The plume of smoke could also be the reaction of coolant leaking onto the hot engine.
Bubbling and Boiling Coolant Aren’t the Same Thing
As your car warms up, bubbling is an indication of rising pressure in the cooling system.
Mind you, the cooling system in most vehicles rely on a leak-free closed circuit of hoses to pump coolant around the engine.
But if air should happen to get into this closed system, it can block the flow of coolant.
One cause is a blown head gasket which allows air from the combustion chamber to enter the cooling system. Once air is inside, the coolant begins to bubble.
Sometimes this is mistaken for boiling which is actually the result of overheating.
Leaks Could Be Another Symptom of Air in the Cooling System
The amount of coolant in the system is important for heat absorption.
Coolant leaking from your car is likely caused by air in the system. And if there’s a leak you likely don’t have enough coolant which will eventually cause your engine to overheat.
Evidence of a coolant leak can be found by a significant drop of the coolant level in the radiator. This causes the remaining coolant in the system to boil which isn’t effective for cooling the engine.
But too much coolant is just as bad as it won’t allow the cooling system to work efficiently.
A Sweet Smell
Another symptom of air in the cooling system is a sweet smell.
Engine coolant like antifreeze has a sweet smell. It’s one of the reasons why animals like cats and dogs are attracted to it.
But ingesting it can make them very sick.
Air in the cooling system can result in a leak which will result in a distinct sweet smell.
Diminished Performance is a Sign That There Could Be Air in the Cooling System
Cooling system failure is one of the leading causes of breakdowns.
At first, you’ll notice that your car is slower than normal to accelerate. Passing fellow motorists becomes a challenge.
This increased heat also reduces engine oil viscosity which makes the once thick oil thin. A lower viscosity means that the engine isn’t properly lubricated.
An unproperly lubricated engine increases friction which increases the amount of heat in an engine. The result of which could be a thrown rod which means you’ll need a new engine.
I’ve seen this happen – twice: Once to my sister’s Saturn SC2 Coupe and once to a co-worker’s Honda Accord.
Poor Fuel Economy Could Be Caused by Air in the Cooling System Forcing Your Engine to Work Harder
A cooling system that isn’t working properly reduces the engine’s ability to use fuel efficiently.
The ECU compensates by adding more fuel for the combustion process to do the same amount of work.
Essentially, if the cooling system isn’t working properly the engine has to work harder to deliver the same level of performance.
This is one of the reasons why regular maintenance of an engine’s cooling system is so critical.
It’s often overlooked.
But all the components of an automobile are interconnected. And when the cooling system goes bad, it’s taking everything else with it.
If Your Heater Isn’t Working Properly, You Could Have Air in the Cooling System
Did you know that the cooling system also affects the ability of your car’s heater to work properly?
Remember we said that once coolant travel through an engine it gets dumped in the heater core.
Heat gets created by the engine’s combustion process. Once your car gets to operating temperature the thermostat opens to allow coolant to circulate through the engine.
As it absorbs heat from the engine. Coolant travels to the radiator where it gets recirculated to the heater core which then distributes heat into the passenger compartment of a vehicle to keep you warm and a cold day.
But if air in the system restricts this flow. The temperature in the car will never warm up on a frosty morning.
Causes of Air in the Cooling System
An engine that overheats often is not good. And if the problem isn’t fixed it can lead to costlier repairs down the road.
Remember we also said that an engine’s cooling system is closed and often pressurized.
A major cause of air in the cooling system comes from this system’s failure to maintain pressure.
This failure to maintain pressure could be the result of a:
- Damaged Radiator Cap: The first thing to check is that the radiator cap has a tight seal against the radiator. The cap is not only responsible for ensuring that coolant doesn’t spill out. It also helps to pressurize the system. It’s failure at high temperatures causes air to leak into the system.
- Blown Head Gasket: Another means by which air gets into the cooling system is through an improper seal of the combustion chamber due to a head gasket that might need replacing.
- Improper Coolant Refill: When refilling the coolant reservoir its important to make sure that air isn’t getting in which can then be trapped in the system.
- Improper Coolant System Flush: An improper flush has the same result – bubbles form as air is forced into the cooling system from the combustion chamber.
Trapped air in the cooling system can become a serious problem for any engine.
And as you see, identifying the issue and causes isn’t too difficult – neither is getting the air out of the system.
If the warning light on your dashboard comes on regularly and you suspect that the cooling system isn’t working properly.
We recommend taking your vehicle to a good mechanic to have it checked out.