Yanmar SD20 saildrive diaphragm

Advanced search->All Forums->Any Date->"diaphragm"............................gives 73 results.

The fairytale about the rubber diaphragm is that the service life is > 25 years. In real life a little shorter. As I remember, Volvo used to recommend 15 years between renewal, but in later years both Volvo and Yanmar are advocating for 5-10 years. Read the search results and be wiser.

Due to Hanse-Werfts faulty placement of the nuts on the engine mounts, my mounts broke in bad weather in 2012. (Metal-fatigue). The mounts were renewed, but while broken, the engine possibly had put extra stress on the diaphragm. Therefore I had it changed in 2014, when my boat was 8 years old.

The workshop manual for Yanmar tells to check the diaphragm(s) for hairline cracks every 1000 hours or 4 years. In my SD50 there are diaphragms A and B with a water sensor between, so if the outer diaphragm is leaking, an alarm sounds.

This is from the abovementioned search on myhanse:

"On Marco's wesailhanse page you can find a manual for Yanmar SD 20-50
Try to read page 49: Every 2000 motor-hours, replace engine mounts, and cone clutch!Or at page 48: Replace rubber diaphragm seal ring every 2 years!
Every year inspect and/or replace flexible engine mounts.Clearance between metal parts minimum 1 mm.
This and much more is found at wesailhanse.se"

Talking to a friend in the marine insurance business, he has never had an incident of a yacht sinking because of a saildrive seal failure, but there are obviously 2 conclusions, either everybody changes them in time, or they never fail.

Mark