A Stubborn water pump, and what I did to fix it.

[PFS]

I bought my third, and possibly my best 9.5 hp Evinrude last fall. This thing starts right up and runs like a top, but it needed a new water pump. After a little bit of a struggle due to corroded parts, I got it apart to the point where I could replace the pump. It turned out that I needed the water pump housing as well, so I ordered one and I also replaced the gearbox seals while I was in the neighborhood. I finally got all my new parts installed, but when I tried to install the lower unit to the engine, I couldn't get it to slide up into place. I had made sure that the impeller and the key were lined up, but it didn't matter because I couldn't even get it close enough to begin with.
I took the pump apart again, and tried sliding the impeller alone up the shaft. Sure enough, the shaft had somehow swelled at the point near where the pump is situated on the shaft, so the impeller couldn't go any further. I had another impeller, and I tried that one too, and it was just as tight. After some thought, I decided the best thing was to grind some material off of the shaft with my small electric grinder. I took my time doing this, and it worked out fine. I didn't go nuts with the grinder, just enough to get the impeller on smoothly.
It is all back together now, and that 9.5 pushes my little twelve-foot tin can like a rocket ship. Still, I'm a little puzzled about how the shaft swelled out like that. Any metallurgists out there?

 

[Rick.]

Re: A Stubborn water pump, and what I did to fix it.

Can't imagine how that could happen but good for you to have figured it out. They are great motors and I do like the look of them. Best of luck. Rick.