Abnormal engine heat dissipation is mostly caused by these reasons

Have you ever encountered such a situation: the engine water temperature and oil temperature are fine in winter, but there is a problem in summer, and the water temperature pointer goes straight to the red zone. Obviously, this is a problem with the engine cooling system. Sometimes the problem is not big, but it is very annoying. What is the reason?

First of all, before we start, let's take a look at the heat dissipation principle of the engine. 

The engine does not work in the optimal temperature range right away. It needs time to warm up to keep running at the appropriate temperature. When the engine is just started, in order to make the engine reach the operating temperature faster, the coolant only circulates in the water channel inside the engine. This is the small cycle.

When the water temperature gradually rises and reaches 76°C, the main valve of the thermostat will gradually open and the auxiliary valve will remain open at a certain proportion. At this time, part of the coolant will enter the large circulation water channel and flow through the water tank radiator to release excess heat, and then reunite with the coolant in the small circulation water channel, so that the engine can run stably in the optimal temperature range of 85-95°C.  

When encountering heavy-load climbing, acceleration, overtaking and other conditions that require great power, the engine temperature will rise sharply. When it rises to 86°C, the thermostat will fully open the main valve. At this time, the auxiliary valve will completely close the small circulation channel. The coolant will only flow through the radiator and dissipate heat through the cooling fan, thereby achieving the effect of lowering the water temperature. The process of coolant flowing through the engine body and radiator is the large circulation.

In summer, due to the high outside temperature, the engine will heat up faster, the small cycle will be maintained for a short time, and it will enter the large cycle faster, and the corresponding cooling fan will start more frequently. In winter, the outside temperature is low, the corresponding water temperature will rise more slowly, and the small cycle will last longer.

Whether it is the large and small cycles mentioned above, or the frequency and speed of the fan opening, they are all to keep the engine in the optimal operating temperature range. Different engine cooling fans have different control methods. Mechanical fans rely on memory metal reeds for connection, while electronically controlled silicone oil clutch fans use water temperature sensors to adjust speed more accurately.

Having said that, let's talk about some common reasons that may cause problems in the cooling system. 

Thermostat failure: From the heat dissipation principle above, we can see that the thermostat plays an important role in controlling the large and small cycles according to the water temperature, which is actually a bit like a temperature control valve. Therefore, once the thermostat is stuck or broken, it will cause abnormal large and small cycles, and the engine heat cannot be effectively released through the large and small cycles, which will eventually lead to high vehicle water temperature.

To put it simply, failure of the thermostat will cause the engine water temperature to not be hot when it should be hot, and not be cold when it should be cold. 

Lack of coolant: Coolant is an important part of the engine's cooling cycle. The engine's long-term cooling cycle will slowly consume the coolant. If there is insufficient coolant, the heat naturally taken away will be reduced.

In addition, if water with impurities is used as coolant for a long time, scale will be generated in the water tank, which will indirectly cause the thermostat to get stuck and increase the flow resistance, and eventually lead to a decrease in the coolant flow efficiency inside the water tank, thereby affecting the entire cooling system. 

The surface of the radiator is covered with too much debris: After a vehicle has been running for a long time, impurities such as catkins, mosquitoes, and dust will continue to accumulate on the radiator. Once too much accumulation occurs, the radiator will be blocked by debris, and the air intake and heat exchange will be greatly reduced, thereby reducing the heat dissipation effect and causing the water temperature to be too high.