Here is a Water Pump Replacement for a 2006-2012 Lexus IS 250. This may also work for the 2006-2012 Lexus IS 350.

Works For:
2006 Lexus IS 250
2007 Lexus IS 250
2008 Lexus IS 250
2009 Lexus IS 250
2010 Lexus IS 250
2011 Lexus IS 250
2012 Lexus IS 250

Source: piercedasian on YouTube

Source: ClubLexus