What Causes a Car Radiator to Frequently Boil Over?
3 Answers
In addition to hot weather, overloaded air conditioning operation and faulty cooling components can also cause a car radiator to boil over. Conducting a comprehensive inspection of the vehicle's cooling system is the primary method to prevent boiling. Check whether the cooling fan is functioning properly, whether the radiator is leaking, and whether there is a lack of coolant. If the radiator is leaking, it needs to be repaired or replaced promptly. If the coolant level is low, it should be replenished immediately. If the coolant appears cloudy or deteriorated, it must be replaced. The water content in ordinary coolant can form a vapor barrier layer on the engine cylinder walls, hindering heat dissipation, leading to engine failure and shortening the engine's lifespan.
Last time my car's radiator kept boiling over, and it turned out to be due to insufficient coolant and a faulty water pump, which caused poor cooling performance in the entire system, leading to inadequate heat dissipation. The boiling phenomenon occurs when the engine temperature gets too high, causing the coolant to bubble and boil. Common causes include leaks in the cooling system, such as aging or cracked hoses or loose connections, which allow coolant to slowly leak out and become insufficient. Water pump failures are also common, where internal impeller wear or jamming prevents proper coolant circulation, leading to heat buildup. Additionally, poor driving habits can contribute, such as prolonged high-speed uphill driving or idling in traffic, which increases the engine's workload and makes it harder for the radiator to dissipate heat, leading to boiling over. If this happens, I recommend pulling over immediately to let the engine cool down, then checking the coolant reservoir level—if it's below the minimum line, top it up. Take the car to a professional shop for inspection as soon as possible—don't ignore this issue, as it could severely damage the engine. During regular maintenance, have the mechanic check the water pump and hoses to avoid sudden problems.
Frequent boiling of the radiator can be caused by multiple factors. For example, a faulty thermostat stuck in the closed position prevents coolant from circulating beyond the engine's small loop, causing temperatures to skyrocket quickly. Fan failure is also common—whether electric or mechanical, if the fan doesn't spin properly, it can't cool the radiator. Another issue is radiator blockage or dirt buildup; when the cooling fins are clogged with dust or grime, heat dissipation efficiency drops significantly. I once encountered this when a faulty fan relay prevented the fan from working, causing the engine temperature to spike dangerously on hot days. Coolant quality matters too—incorrect antifreeze ratios (too diluted or too concentrated) can impair cooling performance. To troubleshoot such issues, first use an infrared thermometer to check temperature variations and pinpoint the problem area, then thoroughly clean the radiator and replace failed components. Regularly check for unusual noises or odors in the engine bay after parking to catch problems early.
