Saildrive Diaphragm Replacement Schedule

[ggray]

Originally Posted by out42

A tiny crack. The sensor was removed and left out for a while, the chamber dried but the ingress continued, so had to be done.

How did it dry out while there was still ingress? Or where you hauled when it dried out, and on launching, the seepage continued?

I'm with Mark, water can easily get there from above. I suspect around the sail drive leak sensor. I have a bit of oil that got in there years ago from being forced out of the sail drive, and I couldn't get it all out.

Hopefully you are one of the few with the serious water intrusion.

[dansand]

We recently had external seals fail on both Yanmar 2009 saildrives (4jh4-TE's but not sure of the SD #) after replacing our motor mounts. Attached is a picture of one of the failed seals. I was not aware of an internal sensor - is it possible this was not wired up on my installation?

[valhalla360]

We just bought a boat and the survey wanted them changed as the previous owner had the boat for 12yrs and had never changed them (not sure how old they were).


The mechanic tried to talk us out of it. We now have nice new seals and after looking at the old ones, we saved them as emergency backups. If we do have a failure and can't get new ones, we can put those on temporarily. I think they were $300 each which is pretty offensive for a rubber donut.


I think part of the issue is rubber fails typically thru UV degradation but down in the engine room under the outdrive, there is no UV. My understanding is the double seal effectively stops growth between the seals because most of the time there is almost no water flow. With no oxygenated water flowing thru, barnacles can't survive. Other than a bit of anaerobic slime, I don't think much could grow in there.


This is our first saildrive boat. We'll have to report back after we've gotten some more use out of her.

[ggray]

There is supposed to be NO water between the two seals.

I have had a small amount of water and/oil that seeped through from the top side, most likely around the water intrusion sensor. I think I will replace the plastic washer there with an O ring.

[valhalla360]

Originally Posted by ggray

There is supposed to be NO water between the two seals.

I have had a small amount of water and/oil that seeped through from the top side, most likely around the water intrusion sensor. I think I will replace the plastic washer there with an O ring.

Sorry, I forget what it's called but there is an outer rubber boot that isn't water tight. That's what I was talking about.

[ggray]

Originally Posted by dansand

We recently had external seals fail on both Yanmar 2009 saildrives (4jh4-TE's but not sure of the SD #) after replacing our motor mounts. Attached is a picture of one of the failed seals. I was not aware of an internal sensor - is it possible this was not wired up on my installation?

Are you saying that the seals failed as a result of the motor mount failing?

Or that they failed while the mounts were being replaced (perhaps motor was shifted too much in the process)?

Or that they failed as a separate event?

Rather surprising that they would fail together, unless there was a disrupting force.

[ggray]

Originally Posted by valhalla360

Sorry, I forget what it's called but there is an outer rubber boot that isn't water tight. That's what I was talking about.

Understood!

[dansand]

They failed the week after the motor mounts were replaced. I suspect they were rather brittle & about 8 years old which was the main issue. I am looking into improving the second seal using the approach in this article - Sail Drives . Concerning not only that both seals failed but that it also led to a small amount of water in the engine room.

[Sonosailor]

If they failed a week after the motor mounts being replaced, then the mechanic was a little rough getting the mounts changed. Definitely, the engine and the diaphragm have to be manipulated to get the mounts out and in. I replaced my motor mounts years ago, and didn't know what I was doing - I deserved to have a leak, but didn't.

[Sonosailor]

I may have messed up, but here are two threads I started on this topic:

1. Why change the diaphragms?:

http://www.cruisersforum.com/forums/...ve-166035.html

2. How I changed mine out:

http://www.cruisersforum.com/forums/...es-166584.html

I hope this is helpful, and that I have referenced them properly. (Nothing in FAQ on how to refer to another thread.) You can also see I had trouble with an attachment.