Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 234Get this manual
CLEANING AND INSPECTION 12Clean all water pump parts with solvent and dry with
compressed airInspect plate and water pump body for grooves andlor
rough surfacesIMPORTANT: When performing gear housing repai rs,
that require removal of water pump impeller, It is recommended that the Impeller be replacedIf it is nec essary, however, to re-use impeller, DO NOT in stall in re-
verseta original rotation, or premature impeller failure will occurOriginal rotation Is clockwise3Inspect impellerReplace impeller if any of the follow-
ing conditions exist:
Impeller blade(s) are cracked, tom or worn
Impeller is glazed or melted (caused by operation
without sufficient water supply Rubber portion of impeller is not bonded to