What Causes the Engine Radiator to Boil Over?
3 Answers
Engine radiator boil-over can be caused by: 1. Insufficient coolant level; 2. Radiator blockage leading to poor circulation or backflow; 3. Coolant leakage obstructing water circulation; 4. Malfunctioning thermostat in small/large circulation conversion; 5. Damaged cooling fan or short circuit causing fan failure/slow rotation; 6. Faulty fan temperature sensor. The radiator's function is: When engine temperature rises, the water pump circulates coolant to lower engine temperature for protection. In winter when coolant temperature drops, circulation stops to prevent excessive engine cooling.
Last time I was on a long drive, the engine radiator suddenly boiled over, with steam billowing out, which scared me into pulling over immediately. This happened because there was an issue with the cooling system, usually due to a few common reasons: first, the coolant level was too low or hadn't been changed for too long, reducing its cooling effectiveness; second, the radiator or water pump malfunctioned, preventing heat from dissipating; third, the fan stopped working, possibly due to a loose belt or a faulty motor. Never ignore a boiling radiator, as excessive engine temperature can severely damage components, leading to costly and complicated repairs. In such a situation, immediately turn off the engine and let the car cool down. If possible, add some water to temporarily alleviate the issue, but be sure to visit a repair shop as soon as possible to prevent a minor issue from escalating. Regular maintenance, such as changing the antifreeze and checking the radiator fan, can help prevent such problems.
The term "boiling over" sounds like water boiling, but it's quite scary when it happens in a car. I experienced it once when I was a new driver. The main reason is the engine overheating due to a cooling system failure, possibly from insufficient coolant or a clogged radiator, which prevents heat dissipation. Additionally, if the water pump isn't working or the thermostat is stuck, the temperature can rise rapidly. If this happens, stop the car immediately and don't open the hood—wait until it cools down before checking, as the steam can be dangerously hot. I always check the coolant reservoir level before refueling and top it up if it's low to keep the system running smoothly. Ignoring it could lead to engine failure, so regular checks are recommended to avoid accidents.
