Several years ago I was having problems with my water pumps going out on my 5.0 Mercruiser engines with the Bravo III drives. I would be driving a long and the pump would start leaking which in turn would get water on the alternator and that would take both out. I thought it was just cheaply made water pumps and the local dealer could find a problem. I started ready every thing that I could and was playing with my smart guages which told me that I had 48 pounds of water pressure. To me 48 pounds of pressure sound good more is better but that was not the case. The pump went out again. I read in the service manual that the pump was suppose to put out between 22 to 26 pounds of pressure. What I found was my heat exchangers was sucking up grass. By restricting the water flow threw the heat exchanger I was increasing the water pump pressure and put more strain on the pumps bearings. In order to solve this problem I installed an in line water strainer and my problems went away.