Hi Mike,
My
Yanmar 2QM15 engine has a
water pump">raw
water pump which leaked as you describe. I'm not sure if your
3YM30 "freshwater"
pump is the same deal as mine but water leaking from the breather hole underneath indicates the
shaft seal is knackered.
A new Yanmar pump is an expensive option but I easily repaired mine after
purchasing a
water pump repair kit and found it fairly easy to do myself. The kit contains a new seal,
gasket and impeller. You should look up a 3YM30
parts catalogue for the appropriate part numbers and go from there.
Parts can be found on Ebay and online dealers.
bony