If coolant begins boiling inside your car’s cooling system it usually means the engine temperature has exceeded safe operating levels. Coolant is designed to absorb heat from the engine and transfer it through the radiator where airflow removes that heat.
When the cooling system cannot regulate temperature correctly, coolant may begin bubbling or boiling inside the expansion tank or radiator. This is usually a warning sign that the engine is overheating.
Ignoring coolant boiling can lead to severe mechanical problems including warped cylinder heads, head gasket failure or permanent engine damage.
Low coolant is one of the most common reasons coolant may start boiling. Without enough coolant circulating through the system the engine cannot remove heat efficiently.
This may cause temperatures to rise rapidly, particularly during longer drives or heavy engine load.
The radiator cap plays an important role in maintaining pressure within the cooling system. Increasing pressure raises the boiling point of coolant.
If the radiator cap becomes worn or cannot maintain pressure properly, coolant may start boiling at lower temperatures.
A radiator that is partially blocked by corrosion or debris may restrict coolant flow and reduce cooling efficiency. This can prevent heat from being released properly which allows coolant temperature to rise.
If the radiator fan fails to activate correctly airflow through the radiator may be reduced. This can allow heat to build up inside the cooling system causing coolant to bubble or boil.
If boiling coolant occurs regularly the cooling system should be inspected quickly to prevent serious engine damage.
MotorLoom analyses vehicle symptoms and overheating issues to help identify possible causes.
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