Depco Pump Company
You are actually talking about the Raw Water Pump on the engine. The Fresh Water Pump circulates antifreeze and almost never fails. You can get an entire new pump or order parts as needed from Depco Pump Company. They can be reached at (800) 446-1656. I forgot to send a bookmark, but they are on the web. Your pump can be found on page 113 in their catalog. All of the parts you need to re-build or replace can be found there. I have an 89 Cat 30 with the Universal M25XP. I noticed salt crystals right under the pump during my winter layup last year. I decided to replace the entire pump, and I kept the old one as a spare. The repacement was very simple except I broke off one of the mounting studs on a Sunday afternoon at 1PM. I was able to find replacements at a hardware store (metric no less). After replacing the studs it was a snap to insatall.