912S coolant leak

[David DeFord <davedeford@attbi.com>]

Our 912S has developed a slow coolant leak (a few drops per day) between
the water pump housing and the engine block.  All of the attachment
bolts feel tight.  Has anyone else experienced this?  I don't suppose
there is an approved automotive-type sealant for the Rotax, that can be
added to the coolant (like Bars Leaks or Alumiseal).  Has anyone been
able to remove the water pump to change the gasket without removing the
engine?

Dave DeFord
N135TD