After leaving about couple of month, tried to start the engine
and heard strange sound from the engine
room which was like slipping sound. And I found out the water
pump pulley was not moving. Immediately stop the engine and checked the impeller but no damage but still the pulley on it was stuck. Tried to rotate the pulley by rattchet and it was heavy at first but anyhow moved. Few more rotating became smooth enough to rotate by hand and got smoother. Then applied marine
grade lubricant and installed the water
pump. Operated about 12 hours at 2000 to 2700 rpm
seems no problem. I'm wondering the cause of this trouble because I found no foreign objects inside the pump nor pulley. Now do I better replace the water pump immediately or not?