What is the reason why the diesel pump is empty?

The air rotation of the diesel engine water pump means that the water pump cannot be inhaled or pumped the water flow during work, causing the water pump to rotate but there is no actual water flow. This may be caused by multiple reasons, the following is some possible reasons:
Water source problem: If the water supply is insufficient or interrupted, the pump may not be able to inhale sufficient water flow, resulting in air rotation. This may be caused by the drying of the water source, the pipeline blocking, and the closing of the water inlet valve.
Inlet -intake problem: When air or gas is existed in the water inlet pipeline, the pump may not be able to form a real suction, which cannot inhale the water flow. This may be caused by the water inlet pipeline that is not fully filled with water, pipeline leakage, or loosening pipeline connection.
Pump body leakage: If the sealing part of the pump (such as axis seal) is damaged or aged, it may cause the cooling fluid leakage, reduce the ability to suck the pump, and thus cause empty rotation.
Pump body blockage: The pump pump into the water outlet, outlet, or the inside of the pump may be blocked by debris, dirt or solid particles, causing the water flow to be unable to circulate, which causes empty rotation.
Pump leaf wheel problem: The damage of the pump leaf wheel or the bending of the leaves may affect the normal pump of the water flow, causing the water pump to be empty.
Motor problem: The motor driven by the pump may cause the pump to work properly, which may cause the pump to work normally, thereby causing an empty rotation phenomenon.
Pump running direction error: If the operation direction of the pump is inconsistent with the design direction, it may cause the pump to effectively inhale and pump the water flow, causing empty rotation.
Insufficient lubrication: The bearings and rotating parts of the pump need to be properly lubricated. If the lubrication is insufficient, the increase in friction may cause the pump to fail to operate normally.
Power problem: Unstable power supply or low voltage may affect the normal work of the motor, causing the pump to be unable to run or empty.
Other mechanical problems: other mechanical problems inside the pump, such as bearing damage, loose connection, etc., may also cause the pump to work properly