Our next big project is the engine on the boat. We have a Yanmar 3GM30F, a trusty and reliable diesel. But - we came back to the boat after leaving it to sit for four months, and the raw water was not being pumped through to the exhaust. The engine is cooled by two methods: an enclosed fresh-water and coolant radiator, similar to a car's cooling, and also by sea water, pumped in past the engine by way of a heat exchanger. If you don't see sea water pulsing out of the exhaust when you turn on the engine, there's a major problem.
First Larry dove down on the boat to check out the through-hull, which was free of barnacles or other crud. Then we started our way back, taking off hoses to check the water influx through the strainer, to the engine. The most likely culprit is usually the water pump on the engine. It has a rubber impeller which needs to be changed as a regular maintenance item. We had last changed it in St. Martin, about a year and a half ago. Here's the water pump. But - it all looked OK.
So, then we started back through the parts.
We enlisted the help of a diesel mechanic at that point. Jose had the official-looking coveralls, but we found out later that he was not the authorized Yanmar dealer and mechanic. No matter, he did solve our problem. He also had no English, but we managed to communicate just fine.
A stray odd plug of Styrofoam had lodged in the exhaust system "el tubo de escape" - we still don't know how it got into the system, as the exhaust is well above the water line with floating debris, and the rest of the system is sealed. We're just relieved to have it fixed and be ready to leave.