1972 Johnson 4HP Outboard Motor Service Manual, Page 13Get this manual
TROUBLECAUSE INCORRECT PROPELLER Incorrect tilt ang1e Poor too 1ubricant(smoking) Propeller slipping Bent or worn propeller Exhaust outlet damaged or c10gged Bent gear housing or exhaust housing (broken driveshafts) A1titude horsepower 10ss Exhaust leaks Overheating CAVIT ATION Protruding attachments too 10ng Bent propeller (vibration) Transom too high Improper 10ad distribution Marine growth bottom Added weight (water absorption) Hook in bottom
PERFORMANCE ON
SUBMERGED MOTORS
motor is 10st overboard whi1e it shou1d a1ways disassembled before any attempt is made to start itOften interna1 parts are damaged, and attempts at starting or running under these conditions resu1t in further damagemotor 10st overboard in salt water shou1d a1ways disassembled and c1eaned before starting is attemptedSome materia1s used in modern engines are subject to very rapid corrosion in the presence salt water and shou1d inspected to determine if rep1acements are required