Every vehicle requires a reliable cooling system to ensure the engine runs smoothly. Often, vehicles use a liquid cooling system, which operates through a network of pipes that transfer coolant to the engine. The coolant is stored in a rubber container called the coolant reservoir and distributed to engine parts. But what happens if coolant bubbling in the reservoir and overheating?
It can be a puzzling situation for many drivers. The cause of coolant bubbling in the reservoir and overheating can vary and may be attributed to various factors.
Coolant bubbling in the reservoir and overheating can be a severe problem for any vehicle owner. Various factors can contribute to overheating, such as a faulty thermostat, a damaged radiator, or a malfunctioning water pump.
Overheating can damage the engine and cause engine failure, which can be dangerous.
Here we will explore the reasons and symptoms of coolant bubbles in the reservoir and overheating. But first, knowing what coolant bubbling is essential and why it occurs is essential.
Bubbling Car Coolant: What Does It Mean & Why Does It Happen?
Car cooling systems circulate coolant or antifreeze throughout the engine using a sealed network of hoses. This system ensures that the head gasket, cylinder heads, and engine block receive a constant coolant flow. And it keeps the engine at an optimal temperature.
However, when air enters this sealed system, it can lead to blockages and bubbling, which can cause the engine to overheat. Most car cooling systems are pressurized and rely on a closed circuit of leak-free hoses to effectively pump coolant or antifreeze throughout the engine.
The formation of air pockets in this sealed system can cause blockages and lead to overheating, ultimately damaging the engine.
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Possible Reasons For Coolant bubbling in the reservoir and Overheating
A coolant bubble in the reservoir can cause an engine to overheat for several reasons. We’ll discuss some possible causes mentioned below:
- Air Pockets
- A Turbocharged Engine
- Low coolant level
- Faulty radiator cap
- Blocked radiator
- Faulty thermostat
- Blown head gasket
- Water pump failure
- Coolant contamination
Bubbling in the coolant reservoir often indicates increased air pressure in the cooling system, suggesting that a pocket of air impedes liquid flow. A common cause of this issue is a blown head gasket. The internal air pressure of the cylinder heads is transferred to the cooling system there.
Coolant reservoirs get bubbles from air escaping. The air inside the cooling system doesn’t just come from a blown head gasket. However, let’s look at other factors that might lead to this problem.
Air Pockets
One of the most common problems with a car’s cooling system is a blockage of liquid flow. As a pressurized, closed system, it relies significantly on its seals to keep the pressure inside.
As a result, if any one of its requirements isn’t met, it won’t function properly, resulting in less-than-optimal coolant circulation.
Properly sealing the system maintains internal temperatures and ensures continuous coolant flow. Coolant bubbles when an engine is revved, but this can be dangerous if one of the seals develops a crack or breach and let outside air in.
The cooling system can tolerate occasional, minor amounts of air pockets. However, if air pockets persist after changing the coolant, it may be a sign of problems with other parts of the cooling system.
A Turbocharged Engine
You do not need constant coolant bubbling because you have a turbocharged power plant. After all, installing a turbocharger into an existing car requires extensive investigation and testing.
You’ll want to have the compression ratio appropriately set and use a manifold and exhaust system compatible. However, if these conditions aren’t met (among others), your coolant may likely boil.
Compression pressure must be raised, sometimes dramatically, for a turbocharged engine to achieve its power goals. Adjustments made by knowledgeable automobile owners or mechanics typically accommodate this pressure rise.
If not, the temperature rise exceeds the automobile system’s average threshold. And raises the coolant system’s working temperature, producing coolant bubbling.
Low coolant level
Also, the low coolant level is a common cause of bubbling in the coolant reservoir. A coolant, or antifreeze, keeps your engine running at its best. By absorbing heat from the engine, it transfers it to the radiator.
Furthermore, it can cause bubbling and blockages in the cooling system. It also reduces the coolant’s ability to absorb heat, ultimately resulting in engine overheating.
Faulty Radiator Cap
Coolant reservoir bubbling from a faulty radiator cap can cause various engine problems. The radiator cap maintains the correct cooling system pressure. However, keeping the coolant at a safe temperature prevents boiling.
A typical radiator cap consists of a spring-loaded valve that maintains pressure in the cooling system. If the valve becomes stuck or fails to seal well, air can enter the system. That causes blockages and bubbling in the coolant reservoir. As a result, the engine may overheat, and the coolant may boil, leading to further damage.
Blocked radiator
The radiator is a vital component of the engine’s cooling system, responsible for dissipating the heat generated by the engine. A blocked radiator can prevent proper coolant flow. Moreover, it can cause the engine to overheat and lead to costly repairs.
A radiator dissipates heat with tubes and fins. Over time, debris such as dirt, dust, and insects can accumulate in the radiator fins, reducing their ability to transfer heat. It can block the radiator, causing restricted coolant flow and subsequent overheating.
When the radiator becomes blocked, coolant flow to the engine is reduced. It causes the temperature to rise. Furthermore, result in bubbling in the coolant reservoir as the coolant becomes hot and expands. If left unchecked, the engine may overheat. Moreover, it can cause severe damage, such as a blown head gasket or engine failure.
Faulty thermostat
The thermostat is a component of the engine’s cooling system that regulates the coolant flow to the engine. Moreover, it ensures it stays at the proper temperature. If the thermostat is faulty, it can cause issues with the cooling system.
Furthermore, it can lead to bubbling in the coolant reservoir and other problems. A stuck thermostat can also overheat the engine and stop coolant flow.
Blown head gasket
Head gaskets keep cylinder heads and engines sealed. If it fails, it can allow coolant to leak into the combustion chamber or enable combustion gases to enter the cooling system.
Moreover, coolant entering the combustion chamber can create white smoke from the exhaust. And combustion gases entering the cooling system can induce coolant reservoir bubbling. This bubbling signifies that the combustion gases force air into the cooling system. However, it’s a serious indication of a problem with the head gasket.
In addition to causing bubbling in the coolant reservoir, a blown head gasket can cause other issues, such as overheating, loss of engine power, and oil contamination.
Water pump failure
When the water pump fails, it can cause bubbling in the coolant reservoir. This indicates that the coolant is not circulating well.
Several factors, including wear and tear, corrosion, or damage to the impeller, can cause a water pump failure. Over time, the impeller can become worn, causing a decrease in the pump’s efficiency. Furthermore, corrosion can occur in the water pump housing. It leads to leaks and reduced performance.
Additionally, damage to the impeller, such as from debris in the cooling system, can cause the pump to fail. The cooling system gets more pressure as the engine heats up. Also, it creates bubbles in the coolant reservoir, causing the coolant to boil.
Coolant contamination
Coolant contamination occurs when foreign substances such as oil, gasoline, or exhaust gases mix with the coolant in the engine’s cooling system. It can cause bubbling in the coolant reservoir. However, it’s a sign of air pockets in the design. That can lead to overheating and other problems.
Furthermore, contamination can occur for several reasons.
A common cause is a blown head gasket, which mixes engine oil or exhaust gases with the coolant. Moreover, it can cause the coolant to become discolored or frothy, indicating contamination. There are also cracks in engine blocks and cylinder heads that can contaminate coolant.
A wrong type of coolant or mixing coolants can also cause contamination. Chemical reactions can cause sludge to form.
Or other substances that can clog the cooling system and cause overheating.
How do you fix coolant bubbling in the reservoir?
Generally, one approach to solving an issue is to focus on eliminating its origin. When the coolant reservoir begins to bubble, the question becomes what to do about it. Allow me to take a peek.
After replacing the coolant, release the air pockets.
Air becomes caught in the system when you drain the coolant tank or radiator and fill it back up. Therefore, make sure all the air is exhausted. After refilling the radiator, running the engine for 15 minutes with the radiator cover off is recommended to let any trapped air escape. Before recovering the radiator or reservoir, this will assist in removing any trapped air.
Fix the broken thermostat.
A broken thermostat allows too much coolant to flow, leading to a boil. Changing out the thermostat with a factory-made or compatible aftermarket model is the best way to prevent this. Coolant circulation will be controlled, and there will be no bubbling if the thermostat functions correctly.
Restore the integrity of the head gasket.
Combustion gas might leak into the cooling system from a faulty head gasket; thus, fixing the leak is essential. To remedy the leak, visit a qualified auto repair shop. You can save some cash by repairing the leak at home with leak repair fluid. If the leak persists, a new head gasket is your best bet.
Head gaskets are located in inaccessible engine areas, making their replacement extremely costly. This is one of the many risks of neglecting a leaking head gasket. And if you choose not to correct it, you could seriously harm your engine.
The radiator cap has to be fixed or sealed.
When the radiator cap is removed, pressure in the system begins to fluctuate, which can cause leaks or even break the radiator. Here, you’ll need to swap out the radiator cap; use only a genuine original equipment manufacturer (OEM) part. Otherwise, the cooling system will leak if the radiator cap is unsuitable.
Repair the leaky coolant reservoir hose or replace it.
A leaking reservoir hose lets in unwanted substances while expelling necessary ones. It’s best to get a new hose as soon as possible. Because not only does air get into the cooling system, but coolant is also dripping out of the broken hose. So you’ll still have to deal with engine overheating due to insufficient coolant.
Fix the heating system by changing the valve and pipe.
Except for the apparent case of air getting into the HVAC system, it is still a problem for those riding in cars. Therefore, switch out the heating valve and secure the hose. You still need to replace the hose if it shows signs of wear.
Get rid of the broken water pump.
The water pump should be turned off at all times. However, a faulty cap prevents the pump from drawing in air. This cap should be replaced immediately. No air can enter the mechanism when securely fastened to the water pump’s lid.
Drain and refill the radiator and cooling system.
Once the coolant has done its job, it becomes contaminated with sludge, filth, and other debris. Because of this, the radiator becomes clogged and cannot adequately cool the vehicle. However, regularly replace the coolant in the radiator or reservoir.
Conclusion
Bubbling in the coolant reservoir can happen for many issues. It includes a low coolant level, a faulty radiator cap, a blocked radiator, etc.
It is essential to fix any of these issues as soon as possible to keep the engine from worsening and the cooling system working well. Regular cooling system maintenance can help prevent many of these issues.
If you see bubbling in the coolant reservoir, you should have a qualified mechanic figure out what’s wrong and fix it as soon as possible.
FAQs
What’s causing my coolant reservoir to overheat and boil?
The coolant can boil if air gets into the system due to a blown or leaking head gasket. The foaming process around the coolant or expansion reservoir is another sign of a failed or blown head gasket, as is the presence of air pockets in the coolant.
How do you stop coolant from boiling?
The problem that needs fixing is the boiling coolant. For instance, changing the radiator cap or fixing the head gasket might fix the issue. If you need to become more familiar with automotive cooling systems, you should probably have a professional take a look at your car.
When a water pump stops working, what happens?
Coolant Leak is one of the 6 Warning Signs of a Failing Water Pump. Several gaskets in the water pump are susceptible to wear and tear—overheated engine. Rust and corrosion in the water pump can cause high-pitched, harmonic whining noises.
There are holes in your leak detection system, or the water pump leaks, causing steam to escape under the hood.
Does a water pump always leak when it fails?
Water pumps that overheat are a common indicator of malfunction. Even if there is no visible coolant leak, the pump mechanism could be broken. Pump fins can wear down and stop moving coolant over time.
Is bubbling in the coolant a sign of a failing water pump?
The bubbling of coolant can be the result of a faulty water pump. The radiator tubes are responsible for cooling the coolant, and the water pump aids in this process. The engine’s pipes and passages carry the chilled coolant to the various moving parts of the machine.
Since there will be no way for coolant to get to the radiator if the pump is broken, to begin with, the engine part won’t receive enough coolant for adequate lubrication. Second, the engine will overheat, and a bubble will form in the reservoir because the circulating coolant isn’t getting a chance to cool.