Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 218Get this manual
10Place small amount of Qui cks il ver 2-4-C Marine ubricant on flat side of im peller drive key, and install key on flat sid drive shaft11 .Slide impeller down rive shaft to impeller dri ve keyAlign drive key with keyway in th center hub of impellerand slide impeller over drive key A visual Inspection of Impeller drive key MUST BE made to determine that drive key Is on flat of drive shaft after Impeller is InstalledIf key has moved off flat of drive shaft, repeat Steps and 10IMPORTANT: When completing gear housing repair, that requires removal of water pump Impeller, It is recommended that the Impeller be replacedIf it Is necessary, however, to re- use the impeller, DO NOT Install In reverse to original rotation, or premature impeller failure will occurOriginal rotation Is clockwiseabcdWater Pump Body Bushings, Nylon Bolls Waler Pump Alignment Pin (2)