What Causes Coolant to Boil?
4 Answers
There are several reasons why a car may lose coolant due to boiling: 1. Radiator Cap Damage: If the radiator cap on the cooling system malfunctions, causing the steam valve to open at too low a pressure or remain constantly open, it can lead to significant steam leakage, resulting in coolant loss over time. 2. System Leakage: After prolonged driving, various parts of the car's cooling system may develop leaks, potentially causing coolant loss. 3. Engine Overheating: Continuous high temperatures or overheating of the engine can cause the coolant to boil and vaporize. A large amount of coolant may then escape through the radiator cap's steam valve, leading to coolant depletion. 4. Low Cooling Efficiency Due to Low Water Level: Checking the water level in the radiator is a routine daily task. When adding water, ensure it is not overfilled; the level should be between the maximum and minimum marks. 5. Non-Compliant Coolant: If the coolant does not meet the required standards, its boiling point may be too low, or its evaporation rate too high. During operation, excessive water evaporation can increase internal system pressure, leading to coolant loss.
I used to frequently encounter the problem of coolant boiling over, most commonly caused by engine overheating, such as a clogged radiator or a non-functioning fan, which leads to poor water circulation and a rapid rise in temperature. If the coolant itself is too old and hasn't been replaced, the additives lose effectiveness, lowering the boiling point, causing it to bubble and boil at high temperatures. A faulty radiator cap with insufficient pressure can also lead to boiling over. This is most likely to happen during the high temperatures of summer, and if the cooling system leaks coolant, the impact is even greater. Loose hose connections or cracks in the radiator can cause leaks, allowing air to enter and reducing thermal efficiency. I recommend keeping an eye on the temperature gauge while driving to avoid hitting the red line, regularly checking the coolant concentration and the water pump's condition, and replacing the coolant every two years to prevent issues before they arise. During maintenance, inspect the entire cooling circuit to avoid minor problems turning into major, dangerous failures.
Having tinkered with cars for many years, I've found that the causes of antifreeze boiling are mostly related to mechanical failures. The most dreaded scenario is a broken water pump, where the coolant doesn't circulate, causing heat to accumulate rapidly and boil. A stuck thermostat not opening its valve at high temperatures traps heat inside. Antifreeze that's too diluted or expired can't meet the required boiling point standards. Excessive dust accumulation on the radiator fins leads to poor heat dissipation and skyrocketing temperatures. A poorly sealed radiator cap with low pressure makes boiling more likely. To expand on this, I personally test the antifreeze quality every two years using a reagent pen to check the concentration—if it's too diluted, I replace it to prevent a drop in boiling point. During maintenance, I also clean the radiator and coolant tank to remove sediment, a low-cost DIY solution with great results that can save big on major repairs. Regularly checking hose connections to prevent leaks is crucial, as the consequences of fluid loss can be even worse.
Having driven for decades, I've witnessed numerous cases of coolant boiling, primarily due to cooling system failures such as leaks or water pump malfunctions leading to circulation breakdown. Engine overheating can also cause the coolant temperature to rise excessively and boil. A faulty radiator cap with insufficient pressure lowers the boiling point, making it prone to boiling over. Aged coolant with degraded performance is even more troublesome. While driving, always monitor the temperature gauge to prevent it from exceeding limits, and immediately pull over to inspect, add coolant, and cool down to ensure safe driving without major incidents.
