I have the same engine
(which is really a Perkins) my water pump started leaking and I replaced it at a cost of $500+ for the part.bought in FL I'll look for the details and advise if you still need them.
When I bought this engine
in 2003 I asked the location of the zincs and was told it didn't have any. So far corrosion
ruined the oil
cooler and now the heat exchager has a hole eated by corrosion
. Volvo charge an arm and a leg for all parts
I'm telling you this so you can check around your engine for possible problems.
s/v Gentle Rain II