How to Replace the Prop Seal on a Johnson Outboard

by Will Charpentier

Every time you go boating where people fish, you're taking a chance on running over a piece of fishing line that someone threw over the side of a boat or from shore. Fishing line that casually wraps itself your Johnson outboard's propeller shaft behind the propeller destroys the prop seal. That lets water into your motor's lower unit. When water in your lower unit dilutes the gear lubricant, your gears start grinding each other down.

Remove the two screws that hold the bearing carrier around the propeller shaft using a screwdriver. Pull the bearing carrier with a flywheel puller.

Peel the O-ring out of the groove on the end of the bearing carrier opposite the propeller end and remove the seal from the propeller end of the bearing carrier with an internal-jawed puller. Clean the sealant from the bearing carrier flange and O-ring groove.

Coat the outer surface of the new propeller shaft seal with a light dusting of spray penetrating lubricant. Use a shouldered bearing driver that only contacts the seal around the exposed set of the bearing's lips to install the seal into the bearing carrier, so that the the set of lips with the larger outer diameter faces inward toward the rear of the carrier.

Apply a coating of waterproof marine grease to the lips of the new seal and to the new O-ring. Install the O-ring to the carrier groove and wipe the carrier surface clean on either side of the groove. Apply a bit of gasket sealant on the threads of the bearing carrier screws and the rear support flange of the bearing carrier housing.

Slide the carrier over the propeller shaft and into the gearcase so the carrier's mounting holes align with those of the gearcase. Thread the mounting screws through the holes and tighten to 70 inch-pounds with a torque driver.

Items you will need

  • Screwdriver
  • Flywheel puller
  • Propeller seal replacement kit
  • Waterproof marine grease
  • Gasket sealant
  • Torque driver

References

  • "Johnson Repair Manual -- 2.5 to 250 HP Models, 2002-2007"; Seloc Marine; 2007

About the Author

Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.