Gone Outdoors

How to Disassemble Outboard Lower Units

by Will Charpentier

From the moment you slide the lower unit away from the exhaust housing of your motor until you pull the final seals and O-rings, you will wonder why you thought the lower unit of your outboard was a mysterious "thing" that you couldn't disassemble. It's a piece of machinery, delicate in some spots and rugged in other, just like a watch. Whether you're overhauling the unit or just replacing parts, if you exercise the right amount of care, everything will fall into place.

Wrap the jaws of a bench vise with thick cloth, for padding. Position the lower unit upright in the vise. Remove the water pump bolts with a wrench and remove the water pump from the lower unit.

Clean the shift rod and driveshaft with a degreaser and coat them with machine oil to aid in removing the gear case cover. Remove the bolts securing the gear case cover with a socket wrench and slide the cover up and free of the shift rod and driveshaft. Lift both the shift rod and driveshaft free of the lower unit.

Remove the screws securing the bearing carrier in the lower unit with a standard slotted screwdriver. Tap the bearing carrier in either direction with a rubber mallet to turn the bearing carrier in the housing exposing the ears of the bearing carrier. Free the bearing carrier from the gear case and pull out the propeller shaft assembly. Remove the seal saver and O-ring from the bearing carrier.

Release the shifter clutch dog from the propeller shaft by pulling the pin with needle nose pliers. Remove the two seals from the bearing carrier with a jawed puller. Remove the driveshaft seals from the gear case cover.

Work the shift rod into the seal and push outward so the seal will pop out of the gear case cover. After the seal has been removed, remove the O-ring.

Items you will need
  • Bench vise
  • Thick cloth
  • Degreaser
  • Machine oil
  • Socket wrench
  • Standard slotted screwdriver
  • Rubber mallet
  • Needle nose pliers
  • Jawed puller

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.