What is an automotive water pump assembly
In the cylinder block of a car engine, there are multiple water channels for cooling water circulation, which are connected to the radiator (commonly known as the water tank) placed at the front of the car through water pipes, forming a large water circulation system. At the upper water outlet of the engine, there is a water pump, which is driven by a fan belt to pump out the hot water in the water channels of the engine cylinder block and pump in the cold water. Beside the water pump, there is also a thermostat. When the car is just started (cold), it is not turned on, so that the cooling water does not pass through the radiator but only circulates within the engine (commonly known as small circulation). When the engine temperature reaches above 95 degrees, it is turned on, and the hot water inside the engine is pumped into the radiator. As the car moves forward, the cold air blows over the radiator, taking away the heat.
Centrifugal water pumps are widely used in automotive engines. Its basic structure is composed of parts such as the water pump housing, connecting plate or pulley, water pump shaft and bearing or shaft-mounted bearing, water pump impeller and water seal device, etc. It is a major component of automobiles.
The engine drives the water pump bearing and impeller to rotate through the pulley. The coolant in the water pump is driven by the impeller to rotate together. Under the action of centrifugal force, it is thrown to the edge of the water pump housing and generates a certain pressure at the same time, and then flows out from the water outlet channel or water pipe. At the center of the impeller, the pressure drops as the coolant is thrown out. Under the pressure difference between the water pump inlet and the center of the impeller, the coolant in the water tank is drawn into the impeller through the water pipe, achieving the reciprocating circulation of the coolant.
The bearings that support the water pump shaft are lubricated with grease. Therefore, it is necessary to prevent the coolant from leaking into the grease and causing emulsification of the grease, as well as to prevent the leakage of the grease. The sealing measures for preventing leakage in water pumps include water seals and gaskets. The dynamic sealing ring of the water seal is fitted with the shaft through an interference fit between the impeller and the bearing, and the static sealing seat of the water seal is tightly pressed onto the housing of the water pump, thereby achieving the purpose of sealing the coolant.
The water pump housing is connected to the engine through a sealing gasket and supports moving parts such as bearings. There are also drainage holes on the pump housing, located between the water seal and the bearing. Once coolant leaks through the water seal, it can be discharged from the drain hole to prevent coolant from entering the bearing cavity, which could damage the bearing lubrication and cause rusting of the components. If coolant still leaks out after the engine stops, it indicates that the water seal has been damaged.
It is generally driven by the crankshaft of the engine through a V-belt. The drive belt is wound between the crankshaft pulley and the water pump pulley. When the crankshaft rotates, the water pump shaft also rotates, and the water pump shaft drives the impeller to rotate, thus converting mechanical energy into hydraulic energy.
The impeller is the core of a water pump's operation. The movement of the impeller itself is very simple; it just rotates together with the shaft. However, due to the effect of the blades, the movement of the liquid in the impeller is very complex. On the one hand, it performs implicated motion along with the rotation of the impeller; on the other hand, it is constantly thrown out of the rotating impeller under the drive of the blades, that is, the motion relative to the impeller. Therefore, the outer diameter of the impeller, the height and Angle of the impeller blades, as well as the gap with the pump casing, directly affect the performance of the pump.
Faults in automotive water pump assemblies are usually caused by the following reasons:
Common causes
Youdaoplaceholder0 Aging of the sealing ring : it causes coolant leakage and the sealing ring needs to be replaced.
Youdaoplaceholder0 The belt is too tight : it increases the wear of the water pump. The tightness of the belt needs to be adjusted.
Youdaoplaceholder0 antifreeze deterioration : Internal corrosion causes damage to the water pump, and the antifreeze needs to be replaced.
Youdaoplaceholder0 Aging/damage of components : The water pump has been in use for too long or components (such as blades, bearings) are worn out and need to be replaced.
Typical symptoms
Youdaoplaceholder0 Unstable idle speed : In winter, the engine may stall and the speed may fluctuate significantly.
Youdaoplaceholder0 coolant leakage : Water is leaking near the water pump, and water marks are left on the ventilation holes.
Youdaoplaceholder0 Abnormal noise : Abnormal friction sounds of bearings or impellers.
Youdaoplaceholder0 cooling system failure : The engine temperature is too high, and the coolant circulation capacity has decreased.
It is recommended to carry out timely maintenance upon discovering the above symptoms to prevent engine damage caused by water pump failure.
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