A common boating mishap is getting fishing line wrapped around the prop shaft behind the propeller of an outboard or sterndrive. Left unattended, the line will melt into a solid blob and can cut into the seals around the shaft, allowing water to leak in and gear lube to leak out. So it’s important to replace bad seals immediately.
This project focuses on a MerCruiser Alpha One drive. You’ll need to source the equivalent specialty tools mentioned and torque specifications appropriate to your lower unit. To prep, put the boat on a trailer, drain the gear lube, remove the propeller and its hardware, and pull the gear case from the drive shaft housing. Now let’s get started.