Summer is the season of frequent strong convective weather, and if there is a short period of heavy rainfall, it is inevitable that the roads will be waterlogged. The meteorological department recently issued a heavy rainstorm warning in nine provinces and regions again, and it seems that it is necessary to popularize the relevant knowledge of vehicle wading driving.
The solution to engine stalling
As we all know, once the engine stalls when the fuel vehicle is wading in the water, it cannot be forcibly started, otherwise it will definitely cause serious engine failure or even scrap; The reason for this is water ingress into the cylinders of the engine, and the common engine used in family cars is an in-line four-cylinder engine, which means an engine consisting of four cylinders, or the engine has four cylinders.
There is a piston in each cylinder, and the piston is reciprocating in the cylinder due to the pushing action of the crankshaft and connecting rod, and the movement from the bottom dead center to the top dead center is called compression; The compression of air creates high temperatures, which evaporate the liquid fuel oil and make it more efficient. But there is also room for air and fuel to be stored, so there is still space from the top dead center to the top of the cylinder, and this part of the space is called the combustion chamber.
Referring to the diagram below, the space in the combustion chamber is very small.
Each cylinder will be connected to the air intake through the intake manifold, and once the water enters the cylinder through the air intake when wading in water, and the water intake is greater than the volume of the combustion chamber, it will cause the engine to stall; Because water is extremely difficult to compress, the amount of water exceeding the volume of the combustion chamber will cause the piston to fail to reach the top dead center, and the failure to reach the top dead center will cause the crankshaft to fail to "turn around", which is equivalent to braking the crankshaft.
Subsequently, if it is forcibly started again, the result is that the crankshaft is forcibly applied to the starter motor, and the force mainly acts on the connecting rod, and the connecting rod may be crushed; There is also a possibility that a broken connecting rod will break through the cylinder block, and the engine will be scrapped to this extent.
Precautions for plug-in hybrid vehicles:
Some plug-in hybrid vehicles will force the engine to start when the battery pack capacity is too low, and if the engine stalls while wading in the water, the control system will most likely force the engine to start continuously. The results are predictable, and there have been a few similar cases. Suppose this is the case, all powertrains are cut off after the engine is turned off, otherwise you have to wait for an overhaul or replacement of the engine assembly.
Hazards after water ingress into the gearbox
When the engine stalls when the fuel vehicle wades in the water, most drivers have learned the correct way to deal with it; However, if the engine does not stall, it is often not thought of going to the system to inspect the vehicle, at best, it is a car wash, but the gearbox is often damaged in this way.
The gearbox does not immediately fail even if water is ingressive, so the emulsification of the transmission oil is the most overlooked.
The gearbox of the car is not absolutely sealed, because the gearbox also generates high temperatures during operation, and the temperature can even be close to hundreds of degrees Celsius; High temperatures can lead to an increase in pressure inside the gearbox, which can cause damage to the gearbox if not relieved. Therefore, the gearbox will have air vents, which are used for constant pressure, but the air vents may also become water inlet holes.
The vents will have waterproof devices, but the water flow will be strong when wading and driving, and the waterproof cap may not be able to play an effective waterproof role; Transmission oil, on the other hand, emulsifies when water is ingested and has the same characteristics as engine oil. The emulsified oil will gradually lose its lubricating effect, and the gears of the engine will appear abnormally worn; At the same time, the solenoid valve of the automatic transmission also needs to use the transmission oil as the force oil to operate, the hydraulic torque converter is more dependent on the transmission oil, and even the wet dual-clutch transmission needs the transmission oil for lubrication and heat dissipation during operation.
Therefore, once the transmission oil is emulsified, it will cause all-round damage to the transmission assembly without dead ends, but the emulsification process is relatively slow, and it is often seriously damaged when the abnormality is found.
Summary:
It is necessary to check the transmission oil of the vehicle after wading driving, of course, this refers to deep wading driving, generally a few centimeters or more than ten centimeters of water depth is no problem; However, the premise is that there is no "surfing" in the process of wading driving, wading driving must be slow, remember the phrase "fast over the sand and slow over the water", wading driving to stabilize the speed of slow traffic, prevent the water splash of the vehicle from damaging the engine and gearbox, and can also be quickly adjusted when encountering rough roads.
When the vehicle breaks down in the flooded road, the correct approach should be to leave the vehicle as soon as possible and inform the insurance company to carry out professional rescue of the vehicle as soon as possible.
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