What Causes High Engine Coolant Temperature?

[SanEmilio]

Here are the specific methods to address excessive engine coolant temperature: 1. If the temperature is too high or the temperature warning light keeps flashing, stop the vehicle to check whether the radiator coolant level is normal, and inspect the radiator, hoses, and all connections for leaks. If no abnormalities are found during visual inspection, refill the coolant as specified and continue driving. If the temperature remains high after driving a certain distance and coolant loss is detected upon stopping, this is mostly caused by sand holes or perforations in the cylinder block water jacket. Upon discovering this fault, repairs should be performed. 2. When the engine temperature is too high, you can touch the upper and lower radiator hoses to determine the fault. If there is a significant temperature difference between the two hoses, it can be concluded that the thermostat is not functioning. 3. If there is air in the cooling system, it can form an airlock, impairing coolant circulation and causing excessive engine temperature. Run the engine at high speed and gently unscrew the radiator cap until gas begins to escape. Some coolant will flow out with the gas. Repeat this process several times until all gas is released. After troubleshooting, promptly replenish the coolant. 4. If the vehicle is driven on dirt roads or muddy sections for extended periods, debris may accumulate on the radiator, which over time affects cooling efficiency and causes high coolant temperature. First use compressed air to blow out the radiator grille, then rinse it with a water hose.

[ElizabethRose]

I've been driving for decades and have encountered high engine temperature several times. The main causes are usually: insufficient coolant is the most common issue, possibly due to aging pipes leaking or evaporation, so you need to check the radiator and hoses for any signs of leakage; secondly, the fan not spinning, especially when parked, prevents proper cooling, which could be due to a faulty sensor or motor; another reason is a stuck thermostat, which blocks coolant flow and directly causes the temperature to spike; additionally, if the water pump belt is loose or the pump fails, it can't circulate the coolant, leading to a rapid rise in temperature. During regular maintenance, I make sure to clean dust and debris from the radiator surface to avoid blockages that hinder cooling. If you notice the temperature gauge rising, don't push it—stop the car immediately and let the engine cool down before adding more coolant or distilled water. Ignoring it can lead to engine overheating, cylinder scoring, and repair costs running into thousands, or even total engine failure. That's the experience I've gathered over the years.