Analysis of the Causes of Engine Overheating When Coolant is Sufficient
Coolant is the medium for heat dissipation in a car engine. The engine's heat is transferred to the coolant, which circulates between the engine and the radiator driven by the water pump, releasing heat into the air within the radiator. Therefore, analyzing its workflow, if the engine overheats despite sufficient coolant, the possible reasons may include the following:
1. There is air inside the cooling system.
Air occupies a certain volume, causing the coolant to appear sufficient, but the engine cooling system is not fully filled with coolant, and the air hinders coolant circulation, leading to overheating or even boiling. At this point, it is necessary to bleed the air. The engine is equipped with bleed screws, usually located above the engine water pump and at higher points in the cooling system channels. Loosen the bleed screw and add coolant to the radiator until coolant flows out of the bleed screw hole. Then, tighten the bleed screw but not fully, and start the engine to circulate the coolant. Air will continue to escape, and coolant should be added as needed based on the level drop in the radiator until no more bubbles emerge from the bleed screw hole. Tighten the bleed screw, rev the engine to raise its temperature quickly. Once the temperature rises, the electric fan will activate, opening the large circulation. Check the temperature difference between the upper and lower radiator hoses. If the temperature difference is small and the electric fan stops after running for a few seconds, it indicates the air has been fully bled. If the radiator's upper and lower temperatures are inconsistent and the electric fan runs continuously, it means air remains and further bleeding is required.
2. The thermostat is damaged and cannot open, preventing the cooling system from performing a large circulation.
Inspection method: Start the engine, increase the throttle to raise the temperature, and when the electric fan begins to operate, check the radiator and the upper and lower hoses. Since the thermostat should open when the electric fan is working, the radiator should be very hot at this time. If there is no temperature difference in the radiator, after ruling out the presence of air, it can be determined that the thermostat is damaged and unable to open. In this case, the thermostat needs to be replaced.
3. Pump failure leads to poor coolant circulation, preventing timely heat dissipation.
After ruling out the thermostat malfunction, we can determine the water pump failure by observing the coolant flow in the radiator. Specific steps: Once the engine temperature has dropped, cover the radiator cap with a wet towel, carefully open it while taking precautions to avoid burns from coolant spray. After opening the radiator cap, start the engine and accelerate to allow the engine to warm up. When the electric fan activates and the thermostat opens, if coolant quickly flows out from the radiator opening, it indicates the water pump is functioning properly. Otherwise, a water pump failure should be considered. Since the cooling system is pressurized, opening the radiator cap breaks the seal, and the pressure generated by the water pump will cause coolant to overflow from the radiator opening.
4. Water pump belt broken
After the water pump belt breaks, the water pump loses power, and the coolant in the cooling system cannot circulate to remove heat. In this situation, a high-temperature alarm will quickly be triggered. This fault of the water pump belt breaking is easy to diagnose; simply open the engine compartment to inspect it.
5. Excessive scale inside the radiator prevents coolant circulation.
This is also a very common issue, but if your car has always been filled with qualified antifreeze and never had water added, the likelihood of this problem occurring is relatively small. This is because qualified antifreeze does not produce scale inside the radiator, preventing blockages.
When a car engine overheats or boils over, it's crucial not to panic. First, pull over to a safe area as soon as possible and turn off the engine to prevent further damage from rising temperatures. Then, you can arrange for a tow truck to take the vehicle back. If the distance isn't too far, you may also wait for the engine to cool down and then drive back at a low speed, but be sure to monitor the temperature gauge closely. Engine overheating is a common issue and relatively easy to fix. However, it's essential to stop the engine immediately when overheating occurs and avoid adding water, as the cost of dealing with scale buildup could far exceed the price of many bottles of coolant. Always choose high-quality coolant with a reliable guarantee, which can last for many years with ease.