After parking, the cooling fan is still running; what is the impact of directly turning off the engine? Is that your problem, then let me make it clear today.
When you stop the car and prepare to turn off the engine, you suddenly find that the cooling fan on the front of the car is still whirring non-stop.
If you turn off the engine directly at this time, there will be two situations: some cars will continue to rotate after the engine is turned off, while some cars will turn off the engine.
The rear cooling fan also stops. So what should I do in such a situation? Is it idling in place and then shutting off after the cooling fan stops, or is it directly shut down?
It is estimated that many car owners have been troubled by this problem. Today, let’s talk about why this happens and how to deal with it.
1. Why does the cooling fan turn after parking?
There are only two situations in which the front cooling fan rotates:
- When you turn on the air conditioner, the rotation of the fan is to dissipate heat to the condenser of the air conditioner, which is the basic guarantee for the operation of the air conditioner.
At this time, the cooling fan is just like the fan of the outdoor unit of the household air conditioner. As long as the air conditioner is turned on, it will keep rotating. When the air conditioner is turned off, the fan will automatically stop.
- When cooling the engine , if you do not turn on the air conditioner, or the fan is still running after turning off the air conditioner, it means that the radiator is cooling the engine.
At this time, the engine coolant flows through the front radiator under the drive of the water pump, rapidly cools down with the help of the cooling fan, and then flows back to the engine. This is the normal working process of the car cooling system.
2. Can the cooling fan be turned off directly when running?
When the cooling fan runs, it can be turned off directly, which will not affect the engine.
We all know that the water temperature gauge will stay in a fixed position after the engine reaches the normal operating temperature, which makes us subconsciously think that the engine’s normal operating temperature is a fixed value.
It is not because it is difficult for the cooling system to accurately control the engine water temperature at a fixed value, and the engine is not so fragile. It is impossible to cause problems because the water temperature is slightly higher or lower. The water temperature fluctuates within a certain range when the engine works normally.
Generally speaking, the cooling system will control the water temperature between 87 and 93 degrees; some may be higher. For example, a certain engine control system is set like this;
- If the engine water temperature exceeds 93 degrees, turn on the low-speed fan for heat dissipation
- If the engine water temperature is lower than 87 degrees, turn off the low-speed fan
- if the engine water temperature exceeds 100 degrees, turn on the high-speed fan for heat dissipation
- If the engine water temperature is lower than 94 degrees, turn off the high-speed fan
- if the engine water temperature exceeds 120 degrees, Turn on the high-temperature warning light
During this series of processes, the engine water temperature fluctuates quite a bit, which will not affect the engine. After all, the engine is not an ice cube and is not so sensitive to temperature.
As long as the high-temperature warning light is not on, it means that the water temperature at this time is completely within the acceptable range of the engine.
The cooling system needs to control the water temperature mainly to ensure that the engine has the best working condition because the high water temperature may cause frequent knocking of the engine and affect the normal operation.
It is not that the engine will fail once the temperature exceeds this range. In addition, it is an exaggeration to say that even if the high-temperature warning light is on, it does not mean that the engine has a problem immediately,
it is just that the system finds that the water temperature cannot be controlled, and if the engine continues to run, it may damage the engine, so the light is turned on in advance.
Early warning let the driver repair it in time.
When the cooling fan is rotating when we stop, it just happens that the engine cooling system is adjusting the temperature.
At this time, the purpose of the adjustment is still to maintain the best operating condition of the engine, not because the engine cannot bear the temperature too high.
We have reached our destination, and we don’t need the engine to continue running, so there is no need to wait any longer; just turn off the engine.
Many parts and sensors are made of non-metallic materials, and various seals on the engine are more sensitive to temperature changes.
After the engine is turned off, there is still a lot of heat remaining in the engine itself, and because the vehicle is at a standstill, there is no air in the engine compartment. , the heat will accumulate a lot, which will increase the ageing speed of the parts.
The cooling fan can blow away the hot air in the engine compartment and bring in cold air from the outside, slowing down the ageing speed of these parts.
Generally, most German cars where the cooling fan continues to rotate after the engine is turned off are mostly German cars.
Because the working temperature of the engine of many German cars is high, the temperature in the engine compartment is higher after the engine is turned off.
To prevent the parts from prematurely ageing, it is necessary to delay the cooling fan for a while.
In some cars, the engine operating temperature is low, and the cooling fan rotates with a delay after the ignition is turned off.
In addition, many German car engines like oil leakage to a certain extent, which is also related to the high working temperature of the engine.
Another point worth noting is that gasoline is particularly volatile. When the engine is running, gasoline flows in the fuel supply pipeline.
After reaching the engine, part of the gasoline in the fuel tank is supplied to the engine for combustion, and the other part will flow back to the fuel tank with the return pipeline.
At this time, the gasoline continues to circulate.
The temperature is relatively stable. After the flame is turned off, the gasoline stops flowing, and the gasoline near the fuel injector of the engine and the gasoline inside the oil pipe will be roasted at high temperatures for a long time.
Some gasoline may be directly evaporated in the oil pipe due to the high temperature and become gas vapour.
It is compressed, so when it is restarted, it may cause insufficient fuel supply pressure, resulting in air resistance and affecting the engine’s normal start and operation.
Therefore, after the flame is turned off, a cooling fan is required to cool the cabin to prevent the gasoline from evaporating and causing air resistance.
Summary: After parking, the cooling fan continues to rotate, not because the engine is too hot to bear, but mainly to adjust the water temperature and make the engine work within the optimal temperature.
Therefore, the direct flameout will not cause the engine to be damaged due to excessive temperature.
Whether the cooling fan rotates after the flame is turned off depends on the manufacturer’s calibration strategy.
As long as the engine’s high-temperature warning light does not come on, we don’t need to worry too much.
WHY ENGINE FAN LOUD
Driving with a car radiator fan that is noisy and sounds abnormal may cause uneasy driving.
Aside from being noisy, a car radiator fan that makes noise can also cause the engine cooling system to not work optimally due to uneven gusts of wind at the radiator cooling water temperature.
If this condition is not corrected immediately, the noise will increase in volume and cause the engine to overheat because the engine cooling system is not working properly.
Radiator fan noise is common on cars that have an electric motor drive. But even cars with belt-driven radiator fans can be noisy and produce abnormal noises.
So what are the reasons for this loud car radiator fan and abnormal noise? Here are some reasons for car radiator fan noise.
Worn bearings in the motor fan
The first reason for the radiator fan noise, which is quite common to find, is that the radiator fan motor bearings are worn out.
The bearing on the radiator fan motor ensures that the fan can rotate smoothly. In addition, the bearing ensures that the fan rotation remains stable.
If the bearings are damaged and worn, the fan rotation will also become throttled and unstable.
Even if the bearing condition is bad enough, it can make the fan’s rotation unstable. This unstable fan rotation often makes a noise when the car’s radiator fan is running.
The position of the fan blades is no longer cantered
The next cause of the radiator fan noise is the fan blade not being centred on the fan blade holder.
This fan blade misalignment often occurs due to a problem with the radiator fan motor (such as a failed bearing) or when the fan motor workload is too high (the fan motor keeps rotating under all working conditions and motor temperatures).
Off-centre fan blades are caused by the melting of the plastic fan blade hinges and aluminium shafts on the radiator fan motor.
The position of the off-centre fan blade causes the cooling fan to roll. In some cases, it even touches the grille, resulting in water leakage from the grille.
The fan blade is broken or damaged.
The last clause of the radiator fan noise is because one or part of the radiator fan blade is damaged, such as a chopped-off (broken in parts) or a broken leaf. A broken fan blade will cause the radiator fan to rotate unstably and abnormally. The result is a very loud noise as the radiator fan spins.
The damaged fan blade can result from throwing stones or wood into the radiator fan while driving, especially when driving through dirt roads and flooding with garbage.
WHY ENGINE FAN STAY ON WHEN AC IS ON
- When you turn on the air conditioner, the fan’s rotation dissipates heat to the air conditioner’s condenser, which is the basic guarantee for the air conditioner’s operation.
At this time, the cooling fan is like the fan of the outdoor unit of the household air conditioner. As long as the air conditioner is turned on, it will keep rotating.
When the air conditioner is turned off, the fan will automatically stop.
2. When cooling the engine, the radiator cools the engine if you do not turn on the air conditioner or the fan is still running after turning off the engine.
At this time, the engine coolant flows through the front radiator under the drive of the water pump, rapidly cools down with the help of the cooling fan, and then flows back to the engine.
This is the normal working process of the car cooling system.