Mercury Mariner 4, 5, and 6HP 4-Stroke Factory Service Manual, Page 29Get this manual
GENERAL INFORMATION
Following Complete Submersion
Submerged While Running (Special Instructions)
When an engine is submerged while running, the possibility of internal engine damage is greatly increasedIf, after engine is recovered and with spark plugs removed, engine fails to turn over freely when turning flywheel, the possibility of internal damage (bent connecting rod andor bent crankshaft) existsIf this is the case, the powerhead must be disassembled