Why does the air in the cooling system cause the system to overheat?
When a cooling system leak occurs, the pressure of the liquid reduces, and the boiling point of the coolant/antifreeze drops as well. Cooling systems are pressurised to raise the fluid’s boiling point, with the pressure cap and overflow assisting in raising the temperature at which the coolant or antifreeze boils.
When a head gasket blows, air enters the cooling system, causing bubbling. At the same time, coolant/antifreeze leaks from the head gasket into the cylinder head. This implies that when the liquid seeps into the cylinders, the cooling system gradually fills with air, lowering the liquid pressure and causing the fluid to boil. Overheating can occur quickly with a head gasket leak, with white steam flowing from beneath the bonnet.
If the pressure at which the coolant/antifreeze flows through the engine is impacted by a leak, the fluid will reach boiling point, causing the engine to overheat, whether it’s due to a malfunctioning pressure cap or a fracture in the engine block.
If you check MOT history of your car, you will maybe surprised to see that your car failed on the emissions test and the overheating engine could well be at fault.
What is the temperature at which coolant/antifreeze boils?
The temperature at which coolant/antifreeze boils is determined by the product’s quality as well as the pressure maintained within the cooling system. Coolant/Antifreeze has a boiling temperature of 129°C and a freezing value of -37°C at normal operating pressure.
However, if the cooling system’s pressure is compromised by a leak or a damaged component, such as a blown head gasket, the coolant’s boiling point will drop as the system’s pressure declines. As a result, when your automobile develops a defect or leak, it might overheat, causing the coolant/antifreeze to boil in the system.
How does air enter the system, and what can I do about it?
As previously said, there are a variety of reasons why air can enter the cooling system, ranging from small to major technical faults. We’ve included some of the locations that are prone to failure and can allow air into the system:
1 — Head Gasket
When a head gasket fails, pressurised air from the cylinders enters the cooling system quickly, causing the reservoir to bubble and coolant/antifreeze to leak into the cylinder head. This can soon cause the engine to overheat, and you should pull over before it gets any worse.
Symptoms:
· Overheating
· Bubbles in the coolant/antifreeze reservoir
· White smoke from the exhaust
· Billowing steam from under the bonnet
The Fix:
One alternative is to book an expert mechanic to repair the leak. However, this may be costly, so if you want to save money, you can apply a leak repair fluid at home. These do create safe, long-lasting repairs if you properly follow the directions.
2 — Coolant System Pressure Cap
To keep the system at a consistent pressure while enabling coolant/antifreeze to flow to the expansion reservoir, cooling systems rely on a pressurised cap. If the cap fails or is changed with one that is incompatible with the system, air can enter the system and create issues.
Symptoms:
· Bubbling in the coolant/antifreeze reservoir
· Bubbles around the cap seal
· Overheating
The Fix:
If the pressure cap develops a malfunction, it must be changed before the pressure shift causes damage to the radiator. Ensure that the cap is replaced with an OEM (original equipment manufacturer) or a manufacturer-recommended component.
3 — Air Pockets in the Radiator
As coolant/antifreeze passes through the engine, air pockets in the radiator can cause blockages. When not enough coolant/antifreeze is given to the system following a coolant/antifreeze flush, any leftover air is expelled.
Symptoms:
· Bubbling in the reservoir.
· Higher operating temperature, which could lead to overheating.
· Potential radiator damage.
The Fix:
After flushing the radiator and cooling system, run the engine for 15 minutes with the pressure cap off after refilling the system. Before replacing the pressure cap, drain any air from the radiator and cooling system.
What Does Bubbling Coolant Mean in a Car?
To circulate coolant/antifreeze around an engine, car cooling systems use a sealed network of pipes. These hoses are connected in a sealed loop, allowing coolant/antifreeze to flow smoothly and continuously to components such as the head gasket, cylinder heads, and engine block, keeping the engine running at the proper temperature.
When air is let into this enclosed system, it can cause clogs and bubbling, which can cause the engine to overheat. There are various probable explanations for air pockets in the cooling system, which we’ll go over in our guide to what coolant/antifreeze bubbles in the system imply.
An overheated engine can also lead to an MOT failure due to the emission test carried out by the examiner. It is suggested that you check MOT status of your car and book your car with your local mechanic to have this matter resolved beforehand. An overheated engine will not only lead to a possible MOT failure but can also lead to total engine failure.
Why is the coolant in my car bubbling?
Most vehicles have pressurised cooling systems that rely on a leak-free closed circuit of hoses to circulate coolant/antifreeze around the engine. When air enters this enclosed system, air pockets can develop, causing clogs and bubbling, as well as overheating.
As soon as you detect your car overheating, search for car garages near me online and book your car in with a qualified mechanic to repair it. There might be a number of issues, or it could be something as simple as air in the coolant system, requiring a coolant service.
Bubbling shows that the cooling system’s air pressure is rising, indicating that a pocket of air is blocking the flow of liquid. A blown head gasket, in which the air pressure inside the cylinder heads is transmitted to the cooling system, is one of the most typical reasons. This escaping air generates bubbling in the coolant/antifreeze reservoir, which is sometimes misinterpreted as boiling.
When you next book your car in for an interim or full service, it may be useful to search for car services in Reading and also book your car in for a coolant service at the same time.
There are a few additional reasons for air within the cooling system besides a blown head gasket, which we’ll discuss later.
