What are the causes of excessive coolant temperature?
3 Answers
Causes of excessive coolant temperature: 1. The coolant level is too low, insufficient circulating water volume or coolant leakage; 2. Blockage, corrosion or excessive scaling in the radiator, cooling water jacket, water distribution pipe, etc., leading to reduced heat dissipation capacity; 3. Thermostat failure, unable to open normally, resulting in poor operation of the coolant large circulation; 4. The electric fan does not work due to circuit or motor failure; 5. Insufficient water pump capacity, loose or slipping water pump drive belt, damaged water pump impeller, poor sealing; 6. Delayed engine ignition timing, excessively rich or lean combustible mixture; 7. Excessive combustion carbon deposits increase the compression ratio, causing detonation or poor engine exhaust; 8. The cylinder gasket is blown, allowing high-temperature gas to enter the cooling system.
Coolant temperature being too high is no small matter. I've driven for over 20 years and encountered this issue several times. The most common cause is insufficient coolant, such as aging pipes leaking or cracks in the radiator. Additionally, a broken fan that doesn't spin or a faulty fan control switch can lead to inadequate heat dissipation, especially during traffic jams or hot weather. If the water pump isn't functioning properly, the coolant won't circulate, causing heat to build up in the engine. Another issue could be a stuck thermostat that remains closed, preventing proper coolant circulation. More seriously, a blown head gasket or internal engine damage can cause temperatures to rise rapidly. I recommend checking the coolant level before each trip to ensure it's between the MIN and MAX marks, with a clear, non-yellowish color. Don't wait until the dashboard warning light comes on to take action, as engine cylinder scoring can lead to expensive repairs.
From a technical perspective, let me explain the possible reasons for excessively high coolant temperature. The cooling system needs to function properly, including the water pump which is responsible for circulating the fluid. If it's worn out or stuck, the fluid flow slows down. If the thermostat gets stuck in the closed position, the coolant can only circulate within the engine, preventing heat dissipation through the radiator. Radiator clogging is also quite common, where scale buildup or foreign objects block the water channels, reducing heat exchange efficiency. If the fan isn't working due to faulty electronic fan sensors or fan motor issues, it can't draw in sufficient air for cooling. Fluid leakage is another major problem - aging hoses, loose connections, or cracked radiators can all reduce coolant volume. Heavy vehicle loads or prolonged uphill driving can also easily cause temperatures to exceed limits. Simple pre-drive checks of fan operation and coolant condition can help prevent major issues.
