Changing the seal on a SD20 Yanmar saildrive

It has been said (often) that cruising is working on your boat in exotic locations. And while that is an overly pessimistic assessment, certainly cruising cannot be entirely a vacation from maintenance.  While Valerie is away, Laurent on s/v Letitgo gets busy on one of those necessary tasks...

Some amazing photos will be present in this post but maybe not for all public; once the Vahine has left the surrounding of the boat, well in my dream… With that said I was left to ponder on what could be done during this sunny day. so let’s “dive” in one of the most interesting subject of all: oil and seals on a SD20 Yanmar saildrive. Please stop all the applause, I know you are excited but one day somebody will do a Google search and will find the solution to a problem a few years ago we couldn’t!

Another highlight of my day is that this yard is on the flight path of the Faa Airport it is not often you have a 340 Airbus doing a rather drastic turn overhead on takeoff with full load! I will spare you the 2am landing of the same bird.

Now let’s go to our interesting subject of the day. Remove the propeller, allen key for the screw at the end. Then remove the cone with a good size screwdriver inserted in the holes present in it, hold the prop, then turn.

Remove your oil or it’s going to be messy.

Remove the zinc then, the two screws holding the full assembly. A bit of persuasion will be needed to get it in your hand. Read hammer and a screwdriver… “easy cowboy!” aluminium is soft.

With a flat #10 wrench remove the five screws but first mark the position. If you didn’t, the hole that doesn’t have one, goes at the bottom.

Now everything should come out very easily.

With the help of a screwdriver, remove the two split seals.

Spend the next two hours cleaning polishing, once that is done re-insert the new internal seal flat surfaced on the inside. And generously coat them with grease.

For the rest it’s just a reverse job and 5 liters of gear oil to complete the job.