Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 126Get this manual
Reed Block Housing Check rubber bleed hosesReplace any hose that is cracked, cut or deterioratingCheck operation of bleed system check valves in reed block housing If valves are working properly, air can be drawn thru check valves "one way" on lyIf air can pass thru check va lve both ways, valve is not working properly and must be replaced Check that bleed system check valves are threaded tight into reed housing Tighten check valves as necessaryInspect passages in reed block housing to be sure that they are not obstructed Lower Ball Bearing
3Th oroug hly clean (with solvent) and dry crankshaft centermai roller bearings Lubricate bearings with light oi l
ACAUTION
DO NOT Intermix halvelof upper and lowercrankl haft centermaln roUer bearlnglReplace bearlngl In pairs only4Tho roughly inspect centermain rol ler bearings Replace bearings if they are rustedfractured, worn, galled or badly discolored