RE: Pathfinder Diesel Engine
My brother in law had one in his Sundowner 30' tug. The boat has been gone for about 15 yrs. now so it is but a memory.
I can't comment on parts availability such as the raw water pump or the other marinization pieces. They may be tough to get. Much can likely be sourced from elsewhere but be a bit carefull as there were not a lot of them, so there may not be a large base of old engines to keep someone supplying parts.
I think the base vw engine was a good little engine, just the marinization pieces that may cause grief.
One thing I do remember and I was not impressed with, the marinization workmanship. He had removed the exhaust manifold for some reason, don't remember When he went to reinstall he couldn't get the gaskets back into place. The engine had two or three individual gaskets stacked to fill the gaps to the head at a couple of the ports. I ended up taking the manifold to work, putting it on the milling machine and facing the mounting surfaces. None of them were in the same plane or flat. There were no machining marks at all, but some sanding had been done. Poor work and could have bee a problem with a seal.