Mercury Mariner 4 and 5HP 4-Stroke Outboards Service Shop Manual 1999, Page 28Get this manual
GENERAL INFORMATION
Following Complete Submersion
Submerged While Running (Special Instructions)
When an engine is submerged while running, the possibility of internal engi ne damage is greatly increasedIf, after engine is recovered and with spark plugs removed, engine fails to turn over freely when turning flywheelthe possibility of internal damage (bent connecting rod andor bent crankshaft) existsIf th is is the case, the powerhead mu st be disassembled