Hi,
It is probably just the front seal leaking. You can prise this out carefully after removing the impeller but leaving the shaft in situ. When you push the new one in, use a socket or something simiar to drift it in square. The seals are avalable from bearing services or whatever they are called these days, but I do not have the part No. anymore. Take your old one in and get few for the price of one from Volvo. Just make sure it is a SS spring inside. By the way, I have actually done this myself ( volvo 2020)
Here is a link to a schematic of the parts
http://www.jabscoshop.com/marine/jabscoshop-spare-parts/29350-1101-pump-19mm-brz-10-flange.htm
Graham
