I have got a Volvo MD17C in my ship, from 1977.
It's not a bad motor, but the spare parts are ASTRONOMICALLY EXPENSIVE!!!!!
I mean out of sight.
In 1997, they wanted (then!) £1300 (about $2200) for an exhaust manifold, £300 (about $500) for a piston (they don't sell oversizes... you have to buy the piston and liner kit). The list goes on.... £49 for a final drive seal.... I found one for £3.50.
I WILL NEVER, EVER BUY ANOTHER SHIP WITH A VOLVO IN IT.
I advise you not to either.
The early motors (MD2, MD3, MD11, MD17) are sound enough... it really is a sound motor series..... it's just you will be close to insolvency if anything semi-major goes wrong. The third-generation motors, the 2000 series, did not have the same reputation for reliability, and fairly promptly, the Perkins-based "Volvo" motors followed.
Here is a wee summary..... Volvo-Penta engine overlook
Note the reference to "lunatically".
It's a pity about the prices. It does not have to be like this.
There are plenty of other fine engines around. I have always liked the look of the Kubota motors (one variant is the Beta Marine series). They are top-flight Japanese motors. Another good motor is the Perkins, or the British-built Lister Petter. A manifold for the Lister Petter 40 hp was about £185 back then, I remember.
I have no interest in the sale of any of these motors. I just don't want you to learn the Volvo parts lesson they way I have.