I'm going through one of my older mercury's and found a bad water impeller. Replacing it isn't a problem, but I do have a couple of questions. First, the foot has some "crud" in it (sediment, caked on oil, etc). What is the best way to clean this? Can I use some aerosol parts cleaner in the foot? Also, there is a plastic pipe in the foot (goes from the impeller housing to a brass tubing) that has seen better days. Is there an aftermarket replacement?
I would check out Grubbs marine http://www.oldmercs.com/. When I bought their waterpump rebuild kit for my '65 Mark 1000 it included a new tube as well as new impeller, seals, etc. I'm guessing they have the tubes themselves as well. At some point someone had figured the tube on mine wasnt very good and used a piece of rubber tube in place of the hard plastic one and it worked great. I put it back to origional, but havent seen that it made a difference one way or the other.
As far as cleaning the housing, I used acetone. Laquer thinner also works well. Mine was bare metal though.