These engines don't use liners. Each cylinder sits on top of the crankcase
opening with a shims between the cylinder base. There is a machine cylinder
skirt that fits into the machined opening in the crankcase for a registered
fit. The shims are inserted or removed to adjust piston top
clearance/compression ratio. Other wise this is a metal to metal fit up.

The water jacket in only in the cylinder casting and there is at least a
half inch of metal in the bottom of this water jacket.

The cylinder are held in place by the four long head studs that thread into
the crankcase. The passage for these four bolt does not pass through the
water jacket.

The oil passage from the crankcase gallery goes up to the head/rockers via
an independant passage in the cylinder casting. Oil runs back via the push
rod opening in the head and cylinder casting.

So there is only one mechanical joint in this whole assembly that could let
cooling water get into the crankcase and that is the head gasket.. It's been
5 years since I had a Volvo MD cylinder head off and I'm not sure there is
an O ring in this location.. However it this O ring were missing, IMHO there
would be evidence of oil leaking from the head/cylinder joint.

--
My opinion and experience. FWIW

Steve
s/v Good Intentions