Water wont hurt the Alt. as much as mud or silty water. I actually pressure wash the engine bay after eaither working on it with power steering fluid everywhere or other nastiness. I just steer clear of the Distributor mostly.

Another thing that helped me is I used to have a problem with where I would go through some mud, some connectors got water in them and my truck ran like <img src="/forums/images/graemlins/butwiggle.gif" alt="" />. I went through EVERY connector and put di-electric grease in it. No problems now!

'90 Trooper - 2.6L 5-Speed - 1" BL - Custom Roof Rack+2x55watt ProComp - Herculined Interior - Pace Setter Header - Dynomax Super Turbo - K&N - ProComp ES3000 Shocks - Optima Red - MSD 6A - 31" Kumho Mudders - Black Rock Crawlers