How to Take Out an Inboard Marine Drive Shaft

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Inboard motor drive shafts are subjected to heavy loads. The thrust from the propeller is transmitted through the shaft into the transmission thrust bearings. Whip loads are exerted on the shaft if it is bent or misaligned. This causes heavy vibration which can damage the cutless bearing and the stuffing in the stuffing box and cause the box to leak excessive amounts of water, possibly flooding the engine compartment. Shafts in this condition must be removed. This is best done on a boatyard with the boat up on blocks.

Things You'll Need

  • 2 pipe wrenches (4-inch opening)
  • 1/2-inch ratchet
  • Socket set
  • Hammer
  • Remove the rudder. The rudder post is usually mounted in line with the drive shaft and it must be removed to gain access to the shaft. Remove the rudder post flange bolts with the ratchet and sockets. Release the clamp bolt on the rudder post flange and tap it up and off of the shaft with a hammer.

  • Lift the rudder from below and swing it clear of the rudder shoe. Slide the rudder post down and out of the rudder post stuffing box.

  • Remove the cotter pin from the drive shaft. Remove the lock-nuts from the drive shaft with a large pipe wrench. Lock the shaft inside the engine room with the other pipe wrench to prevent the shaft from rotating.

  • Remove the propeller. Pull or gently tap the hub of the propeller with a hammer to break it loose from the shaft. Slide the propeller all the way off and put it aside.

  • Remove the drive shaft/transmission flange bolts. Release the flange clamp bolt. Slide the shaft down far enough to allow the flange to be tapped off of the shaft with a hammer. The shaft is now bare and may be removed. Slide the shaft down and out of the boat.

Tips & Warnings

  • Check the cutless bearing and intermediate shaft bearings and replace if needed. This is a great time to change them once you have the boat out of the water and the shaft is out.

References

  • Capt. TJ Hinton; commercial fishing vessel captain; Gulf Coast, Miss.
  • Photo Credit Hemera Technologies/AbleStock.com/Getty Images
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