You are now a further year in with your Volvo D2-75. How is it going?
I would love to do a rebuild of the TMD22 but it's not vaguely economical here in Hong Kong.
After everything Ive read on the Amel forum I was more of less convinced that the D2-75 was the engine for me too. As such have been googling this engine for reliability and the reading is not good concerning the mechanical data interface unit, some of which it appears Volvo have just recalled. They are now onto their 6th version of the MDI. Have you had any trouble with this item. Although this engine claims to be "electronics free" it's actually not.
Yanmar are quite hard to deal with when it comes to the isolated negative earth with huge lead times, which has got me running back to Beta ....which is where I actually started.
The Beta man looked at the SM and the power curves for the TMD22A. None of us have ever got that engine above 2800 rpm which is actually at best 60HP! 78 HP doesn't occur until 4500rpm. We have all been sailing round the world quite happily with that out put for many years. He suggested to me the BETA 60 was the the ideal replacement as it almost exactly replicates that part of the TMD22A power curve that we've only ever been able to use but at a higher torque. These days every one seems determined to put bigger and bigger engines in their boats, but I'm not convinced!
If you've time I'd love to hear how your D2-75 is going?