Re: Volvo MD 2B
All other things being equal, this would not be my engine of choice but I think that they have received a worse reputation than is warranted.
From a use standpoint, these engines are loud, vibrate a lot and don't make a lot of power. On the plus side, they tend to just go.
From a maintenance standpoint, these engines tend to be very reliable and need very little maintenance but when they need something, the parts are pretty expensive. Part availability can be a bit slow but I have never been unable to find a part which is good.
Common problems on these are cooling issues and hard starting due to low compression. It sounds like the one you are looking at is FWC which is a good start towards dealing with cooling issues but you should take it out and run it at full load for a long time and make sure that everything looks good. It is also worth doing a compression test and cold starting the engine. These engines tend to run fine when their compression gets poor but they get really hard to start. They were never good at cold starting so if you plan on sailing in cold weather, that would be a concern. The other thing that I would do is take an oil sample and send it to someone like blackstone labs, it is cheap and will tell you a ton about the engine.
If you plan on keeping this boat for 20+ years, you should probably factor in the cost of replacing the engine with something like a Beta but if this is a 5 year boat, I wouldn't think twice about it.