Cooling Mechanisms of Car Engines: Understanding the Big and Small Circulation Systems – A Crucial Inspection
Car engines don’t rely on natural airflow for cooling because their operating temperatures can reach up to 2000°C. Instead, they are equipped with a cooling system responsible for temperature regulation. The primary function of the cooling system is to dissipate heat from the engine’s heated areas promptly, ensuring the engine operates optimally.
The cylinder block undergoes cooling through the circulation of coolant, featuring coolant passages designed within the engine cylinders. During engine operation, heat is circulated through a water pump, compelling the water to circulate. After generating heat in the engine combustion chamber, it is directly transferred to the cylinder walls.
Next, the coolant circulates for heat dissipation to cool the cylinder block. As there is a “big circulation” for cooling, there is also a “small circulation.” The working principle of the “small circulation” is similar to the “big circulation,” except that in the “small circulation” cooling method, the coolant does not enter the interior of the water tank. Instead, it allows the coolant to flow out, circulating internally within the engine.
To differentiate whether the refrigeration system is in the “big circulation” or “small circulation,” it is as simple as observing whether the thermostat is functioning. In essence, when the thermostat is working, the refrigeration system enters the “big circulation,” and vice versa – it becomes the “small circulation.” The thermostat’s purpose is to control the temperature of the engine coolant.
When the coolant temperature is below the working temperature, the engine coolant flows back to the water pump inlet through a bypass. For instance, during a cold start, the thermostat will close to quickly raise the engine temperature, making cooling and insulation work achievable. Although cooling can be done, the results are challenging to quantify and need to be measured. If you are confused, consider addressing the issue from three aspects: water, oil, and air.
The cooling form of car engines has transitioned from air-cooled to more efficient water-cooled systems. The system directly handles engine cooling, emphasizing optimization and improvement as a primary goal. Understandably, when my coolant temperature is consistently high, the most direct solution is to replace the radiator with a larger and thicker one.
A larger and thicker radiator allows for better heat exchange between the water in the radiator and the air, effectively lowering the water temperature. However, to state it plainly, if the engine has not undergone significant repairs, it is not recommended to replace the radiator. This is because an excessively low engine temperature is unfavorable, leading to reduced combustion efficiency, increased exhaust emissions, and compromised engine lubrication performance.
Engine oil, if you opt not to replace the radiator, can achieve cooling goals through minor adjustments such as the thermostat, radiator cap, fan, and water in the radiator. However, there is also a system called the “off-time ignition system.” This system adds injectors in the exhaust manifold, utilizing this feature to inject fuel. This detonation aims to keep the turbocharger at full pressure continuously to reduce turbo lag.
This detonation serves to prevent pressure reduction in the turbocharger, maintaining it at full pressure during deceleration into turns. Turbo lag is detrimental during acceleration out of turns, so this method is employed to address the issue.
The water pump is the driving force behind the coolant circulation. In most household cars, the water pump is mostly driven directly by the engine belt. Water pumps are generally resistant to problems, with the most common failures being corroded pump impellers or slipping pump drive shafts. Corroded impellers can lead to poor or non-circulation of coolant, preventing the removal of heat.
When the water pump shaft slips, the water pump pulley rotates normally from the outside, but the impeller inside cannot rotate or rotates too slowly. This can also result in poor or non-circulation of coolant, which impedes heat removal. Check the position of the car coolant; if there is a lack of coolant, the water temperature is undoubtedly very high. Check whether the thermostat can open normally; the thermostat naturally opens and closes based on the water temperature.
When the car is just started, the water temperature is low, and the thermostat is essentially closed, causing non-circulation of water, rapidly raising the engine temperature. After the water temperature rises, the thermostat opens, and water can circulate for cooling. If the water temperature rises but the thermostat cannot open, the car cannot circulate inside, resulting in high water temperature, indicating a faulty thermostat.
Check the radiator fan: when the set temperature is reached, the radiator fan does not turn. However, the coolant radiator cannot quickly exchange heat, causing the water temperature to rise. Check the radiator and circulation pipes. In some old cars, if the coolant is not replaced for a long time, the radiator may become blocked, hindering water circulation.
It may also cause the engine temperature to overheat. This needs to be checked carefully. Lastly, if the car engine is running normally and can dissipate heat by itself, if there is high temperature, please contact a professional. After all, professional work should be done by professionals! What are your thoughts on this matter?