The oil seal, mechanical (ceramic) water pump seal and sealing washer for the water pump are a pain in the a$% to change. Use ONLY new Yamaha parts unless you want to get alot of practice changing these parts. The liquid paths from the coolant side to the weep hole are: 1. leaking past the sealing washer under the impeller bolt, 2. leaking past the metal portion of the ceramic seal which is pressed into the crankcase, 3. leaking through the ceramic to ceramic mating surfaces or 4. leaking past the impeller half of the ceramic seal, between the seal and the impeller.