What's the reason for high coolant temperature?
4 Answers
The full name of antifreeze is antifreeze coolant, meaning it has the function of preventing freezing. Antifreeze can prevent the coolant from freezing and cracking the radiator or damaging the engine cylinder block or head when parking in cold winters. There are three main reasons for high coolant temperature: 1. Improper addition and replacement of antifreeze: This can cause early blockage of the engine water passages and radiator, leading to high water temperature. Antifreeze should be replaced every two years, and only original antifreeze should be used during replacement and addition. If the concentration is too high, it can result in poor heat dissipation and engine overheating. 2. Leakage in the cooling system components: If there are leaks in the cylinder block, cylinder head, cylinder gasket, heater radiator, water pipes, rubber hoses, or drain switch, it will reduce the water volume and decrease the ability to absorb heat energy from the cylinder, causing the coolant temperature to rise excessively. 3. Air in the pipes, idling operation.
I often encounter the issue of high coolant temperature, most commonly due to insufficient coolant or leaks. Once, I found a loose hose connection at the radiator causing a leak, and topping it up fixed the problem. Additionally, a clogged radiator or a non-functioning fan can cause the temperature to spike, so it's necessary to check if the cooling fins are blocked by debris. For older cars, the water pump might fail or the thermostat could get stuck—the water pump is like the engine's heart, failing to circulate coolant, while a stuck thermostat blocks the cooling passage. The most troublesome scenario is a blown head gasket, where exhaust gases enter the cooling system, causing the temperature to skyrocket immediately. This often happens in summer traffic jams—when the coolant warning light comes on, you must pull over, or else engine seizure could lead to costly damage. When stopping to cool the engine by opening the hood, remember never to open the radiator cap directly, as the escaping steam can cause severe burns.
Don't panic if you see the temperature gauge in the red zone, first find a safe place to pull over. I've dealt with this many times, and it's usually a cooling system issue: either the coolant is below the minimum level, or the radiator is clogged with scale hindering heat dissipation. Fan problems are also common—loose belts or faulty relays can cause the fan to stop working. If the thermostat isn't opening and closing properly, the engine won't cool down as it should—this part is hidden inside the thermostat housing. If the water pump impeller is corroded or the bearing is damaged, the coolant won't circulate properly. Also, check the overflow tank for bubbles—if there are any, it might indicate a cylinder head gasket issue. For regular maintenance, remember to flush the radiator periodically and change the coolant every two years to prevent 80% of overheating issues.
The root cause of coolant temperature rise lies in an imbalance of heat dissipation. The engine generates substantial heat during operation, and the cooling system is responsible for removing it: coolant flows through the cylinder block to absorb heat, the radiator dissipates heat through airflow, and the fan assists in cooling. Any malfunction in these components can lead to heat accumulation. Coolant leaks are the most direct issue—check hose connections and radiator welds. A water pump failure is often due to bearing wear, accompanied by abnormal noises. Thermostat malfunctions come in two types: a stuck-open thermostat causes slow warm-up but not overheating, while a stuck-closed thermostat is the main culprit for high temperatures. If the fan isn't spinning, inspect the circuit and fuses. For modified vehicles, improper coolant ratios can affect the boiling point. Prolonged high temperatures can damage the metal structure of the cylinder block, so addressing abnormal coolant temperature promptly is crucial.
