2009 Saildrive Diaphragm Failure

[dansand]

We have a pair of 2009 4JH4-TE (75 HP) Yanmars with about 1800 hours that recently had both Saildrive Diaphragm's start leaking (pic attached). We replaced both set of motor mounts recently and started noticing water in the engine room. Is there guidance on how often these should be replaced? Is this an anomaly or has anyone else experienced something similar. It is quite concerning as we had to get the boat out of the water to repair and could have been quite an issue had we not been close to a travel lift.

[DotDun]

Mine are 12+ years old and still good.

Your motor mount project is curious. It almost looks like the diaphragm was torn, I wonder if the engines were lifted/jacked up changing the motor mounts causing the saildrive to tilt enough to tear them?

[AD28]

I see yours is Yanmar. What I can tell you is that Volvo recommends a 7-year saildrive boot replacement schedule.

Now I'm sure you can push it, but we are talking about a rather large hole in your boat...

[Captain Bill]

I wonder if your engine mount issue did not contribute to the failure. I replaced my 13 y/o sd40s last summer. One of them had the original seal in it and it looked brand new. I had the other drive out in 2008 and replaced the seal in it. It also looked brand new. I kept it as a spare, but never needed it. If you had excessive vibration from a bad engine mount it might have caused a fatigue failure between the part of the seal held tightly against the drive and the more flexible part in the disc. It looks like that is where it failed in your photo.

[aluijten]

Originally Posted by dansand

We have a pair of 2009 4JH4-TE (75 HP) Yanmars with about 1800 hours that recently had both Saildrive Diaphragm's start leaking (pic attached). We replaced both set of motor mounts recently and started noticing water in the engine room. Is there guidance on how often these should be replaced? Is this an anomaly or has anyone else experienced something similar. It is quite concerning as we had to get the boat out of the water to repair and could have been quite an issue had we not been close to a travel lift.

You may need to check the height level of the engine/transmission in relation to the the hull. Normally that should be a given with the standard engine foundation supplied by the engine mfgr. but it could be differnent for your situation. Rule of thumb is that the seal has no "positional force" applied to it when bolted down to the hull.

[ggray]

My seals are 16 years old...I've got to think the engine mount replacement contributed to the seals' demise.
At least, I hope that's what did it.

[Dulcesuenos]

Just wondering how bad was the job? Any tips or learnings for others who may need to do the same in the future?

Sent from my PLT1077G using Cruisers Sailing Forum mobile app

[Privilege]

I suspect that Dotdun has hit the nail on the head. These diaphragms rarely fail without some extreme external force. I suspect that whoever replaced the engine feet, forced the saildrive gearbox backwards in order to lift the engine out rather than lifting the engine forwards to disengage the pinion shaft. Either that, or the saildrive was forced to one side when reinstalling the engine.

[ggray]

Those seals are pretty tough.

I had part of a 3GM30 piston break off at about 4 yr. I pulled the engine and took it to Mack Boring.

While waiting for the engine to be rebuilt, I went off for a short cruise, probably just a weekend. At speed under sail, that sail drive moved around quite a bit! I don't think I would do that again, but the seals for both engines are still going strong starting the 16th year.