For the Volvo Penta Saildrive (S 120), the prescribed maintenance cycle for changing the diaphragm is 7 years. In regard to the diaphragm, which is made of more than 5 mm thick special rubber and should not be exposed to any significant mechanical or chemical stress under normal circumstances, this is quite a sporty rhythm..
I have owned my boat for over 10 years without ever having replaced the diaphragm and assume that the previous owner never did either in the years before. As far as can be seen from the engine room, the old diaphragm was in excellent condition, only in the front hard-to-reach area under the engine was a yellowish coating visible, which I can not assess or explain.
If it were only a matter of the diaphragm, I would take my chances and continue to drive with the old diaphragm until there are serious signs of wear or leaks. Then there would still be enough time to react. If it wasn’t for the seacock for the cooling water supply at the saildrive. It is extremely sluggish and can hardly be operated properly. The plastic washer originally intended for the closing is no longer usable at all, because it has a much too small lever. The plastic square for the lock, on which the disc once sat, can still somehow be gripped and operated with aids, but it is not safe to handle and it is only a matter of time before the square will be round. An unfortunately well-known and safety-relevant problem.
Since the seacock can not be managed without the removal of the Saildrive, I decide to make nails with heads and replace the diaphragm and valve on this occasion. The exchange is a complex and also somewhat more demanding work, which can quickly cost up to 2,000 €, if a commercial service provider takes over. For this reason, I consider doing it myself and look on the Internet, what I can find so DIY instructions and experience reports.
By far the most detailed and instructive report I could find is from Chris, who runs the vlog “Sailing Britaly”. He describes the individual steps and also the unexpected challenges so detailed and clear that even I as a layman get the courage to try it on my own. I can only recommend to anyone who wants to do this work themselves to take a close look at Chris’ report: you can’t show it any smarter than this.
Find here how I did it: