A: ①The impeller on the shaft is loose
②The gap at the rear end of the pump shaft is too large
③The rotor blades and the pump body wall rub against each other
④The pump bearing lacks lubricating oil
⑤ The gap between the shaft and the bearing is too large
⑥The impeller pin breaks
⑦Water pump bearing damage
⑧The seal of the water pump is too hard