I can relate to both of the general positions expressed above -- "If it ain't broke, don't fix it" has merit. It's basically what I've decided to do with my older engine -- the issues I have with it are inconvenient and cosmetic (e.g. oil leak and other minor things like that). But then, I'm not thinking of sailing off over the horizon. If I were I think I'd replace the engine. Reasons are these (and they may not all hold in your situation):
1. There are a limited number of places in the South Pacific where you can have an engine rebuilt / a boat repowered with confidence that it will be done right. There may be a guy who can do it in Fiji, but I know there are probably four to five really competent mechanical shops in major New Zealand or Australian ports. Outside NZ and Oz, and maybe Tahiti, I really don't know how good the mechanical trades will be. (Others may have first hand experience with engine work in the Pac. islands, I dont. I've been to many of them by air and few have impressed me as the kind of place where I'd want to have major engine overhaul work done). Remember as well that if you repower in a far away place, you may also have to rework other elements of the drive train. New engine might mean a new prop -- new prop might require new shaft, etc. While the local diesel mechanic in Tonga may be able to rebuild the engine, can he engineer and configure the other elements of your drive train as well?
2. After major engine work is done you're going to want to hang around for a while to run the engine in a bit and make certain everything is working as it should. I have friends who had major engine work done (or mis-done) in Turkey and they have been dealing with a cascade of problems that originated with the Turkish mechanic all across the Mediterannean -- including a $1000 towing bill and an haul out in Corfu to deal with a misaligned prop shaft. Is the place where you finally decide you need to replace or rebuild the engine, a place where you want to hang out a while to make sure it all works as advertised? That's impossible to know.
3. In remote parts of the world it will take a while to order an engine or rebuild kit, and you may not be able to get what you want everywhere. It's conceiveable that it could take months from the time you decide to repower / rebuild until you are ready to sail again (order the parts / engine, wait for it to be shipped, time in transit, time to clear customs, time for mechanical work to be done, etc). Unless you're in NZ or Oz, there will be the issue of making sure you have time to get the work done and get out of the cyclone box. Break down in Tonga toward the end of the sailing season and you may not be able to get the work done and get out of the box.
4. It may cost more to have work done in remote places -- not so much because of the mechanic's hourly wages, but from freight costs, customs duties, frieght forwarding fees, etc. Importing an engine or even a major parts kit into a remote So. Pac island nation could be very expensive.
If you decide to go with the old engine, you might want to first research some of the above issues before you leave -- i.e. know what your options are, where you can get work done competently, what types of engines are available, what it would cost to import an engine/parts, etc. Cruising guides may provide a place to start this research.
With luck you probably won't need to use your engine that much in the So. Pacific -- winds are pretty reliable there. I don't know where you're starting from, but there may be a few days on the engine out of Panama or even getting off the Pacific coast until you find the wind, but once you're in the trades the hours on the engine should be relatively few.
The decision to replace/repower or go with what you've got also will depend on your budget. There may be other things more valueable to you in the So. Pac than a new or rebuilt engine -- e.g. a watermaker, new sails, etc.??
Good luck and have a great trip!!
Last edited by billyruffn; 12-09-2008 at 02:39 AM.