1971 Johnson 40HP outboards Service Manual, Page 14Get this manual
SUBMERGED MOTORS If motor is lost overboard while running, it should always be disassembled before any attempt is made to start itOften internal parts are sprung and running under thes conditions can result in permanent damage
A motor lost overboard in salt water should always be disassembled and cleaned before starting is attemptedSome materials used in modern engines are subject to very rapid corrosion in the presence of salt water and should be inspected to determine if replacements are requiredA motor lost overboard in fresh water can usually be safely started
if recovered within twelve hours providing no sand or silt is present