I'm sure this may sound dumb to most of you, but I need to ask it anyway. I went to replace an impeller on an '86 Mercury 25hp the other day, because it had been sitting for about ten years. The job seemed to be going well for a while. The lower unit came apart nicely, and I easily disassembled the water pump. When I romoved the cap of the water pump however, I realized that it had been assebled or reassembled with a rubber-like sealant, in addition to the O ring that normally exists. I cleaned the whole thing off, and didn't think a thing of it until I reassembled it. It was then that I realized that the cap sat nicely over the new impeller and on the face plate in all the corners in which there was a bolt (4), but there remained a gap between face plate and the cap along the longer sides. I assume that this is not normal, and perhaps why I found the sealant in the first place. I too then used a sealant, but the sealant merely fills the gap, and I'm not really sure if this will remain water tight. Is this an unusual situation, and did I handle it right? How can I confirm that it's water tight before I bring it out to salt water and have it eat up the lower end/drive shaft? Any help here would be greatly appreciated.
