2000 Yamaha YFM400FWA(M) Factory Service workshop Manual, Page 221Get this manual
WATER PUMP
WATER PUMP ASSEMBLY 1.Install: Oil seal New (into the water pump housing 2) NOTE: Before installing the oil seal, apply tap water or coolant onto its outer surfaceInstall the oil seal with socket that matches its outside diameter2.Install: Water pump seal New (into the water pump housing 2)