Yamaha Marine Outboards Factory Service / Repair/ Workshop Manual 225G 250B L250B, Page 150Get this manual
WATER PUMP (REGULAR ROTATION MODELS)
INSPECTING THE IMPELLER HOUSING
Inspect: Impeller housing Cracksdamage Replace
INSPECTING THE IMPELLER AND IMPELLER HOUSING CUP
Inspect: Impeller Impeller housing cup Cracksdamage Replace any defective parts
INSPECTING THE WOODRUFF KEY
Inspect: Woodruff key Damagewear Replace