Engine destroyed by anti-siphon valve
I recently purchased a 1991 43' moderately heavy sailboat in Annapolis after I received a glowing survey, successful sea trial and reassurances from the owner and broker that everything was in great shape. I signed the papers, then had the fuel polished, and had a diesel mechanic change filters, and do baseline service. When he started the engine, his face went blank. The engine was loping at low speeds, and had had a unsteady sound. He unloaded the fuel injectors by cracking the connection one at a time, and found the #2 cylinder dead. The local Yanmar dealer did a compression check, changed the injectors, and still no #2. He looked into the cylinder with a boroscope, and found "sodium deposits" from seawater in the cylinder. The most likely source was seawater siphoning back into the engine likely because of a bad antisiphon valve. After removing the head, and measuring the cylinders and spotting extensive corrosion, he concluded that the engine needed extensive overhaul, and it may be more cost effective to replace the engine. In any event, the engine will have to come out of the boat. Fortunately, the existing exhaust has 3" pipes, required for the new Yanmar. Ironically, the boat has never left the slip since I owned it, (only a couple of weeks)
I am planning on replacing the Yanmar 4JH2E (1991 54 HP with 3000hr) with a new Yanmar 4JH4TE (75HP and only slightly more expensive). The gearing will be optimized for use with my existing Autoprop.
Does anyone have experience with a bad survey, and engine flaws from the previous owner (who must have known if he did the service he claimed)? Are there any big penalties going to a more powerful engine (turbo with same block size)?