I replaced the impeller on my 82 Mariner 25M today and when I started it up there was still no water pumping thru! I dropped the lower unit again and tried putting water up the pipe and it went up and came out no problem! Then I sprayed water into the pump thru the water oulet and water came out no problem! So then I took the water pump apart again and found that my new $45 impeller was disintegrated! What the hell could have caused this? The inside of the housing looks ok and feels ok!