Hi Larry,
In addition to Steve's good advice there, have you been in touch with Moyer Marine? www.moyermarine.com

Their Atomic 4 service and overhaul manual is priceless for the do-it-your-selfer. I rebuilt my water pump about two years ago and am planning on buying a "back-up" rebuild kit to have on the boat. Their kit is $56 plus shipping and can be viewed on their website. Just last week I had an overheating problem and it turned out to just be a broken hose from the thu-hull raw water supply. Spooked me enough to get a spare impeller kit! They suggest changing this impeller every two years but that is, of course, up to the captain. My last one had to be at least six years old, but when it came apart it did it all at once!

Water pump is on the starboard side, just behind the alternator. Pulling the back plate and doing the rebuild is a snap, but I would recommend Don Moyer's book as a proper guide. Others on this site may know of other avenues.

Good luck w/ the engine!

Bill

La Campana