Yanmar Saildrive Leak

[captjohn360]

yo i eeehave a leak in my saildrive boot how do i fix it ....jt

[Lucky]

Lift the boat onto the hard immediately if the alarm for water ingress has sounded! Can only be fixed by replacing the booth.

Happy lead ree sailin

[Capt. Ray]

Originally Posted by Lucky

Lift the boat onto the hard immediately if the alarm for water ingress has sounded! Can only be fixed by replacing the booth.

Happy lead ree sailin

Immediately? If there isn't much water getting into the engine room through the boot then personally I would schedule the next haulout for a boot replacement. The warning is an indication that it's time to replace the boot, not some dire prognostication that the boat is about to sink.

Check the boot for cracking, perished rubber etc. then make your decision.

[rabbi]

If the alarm goes off I would look for a nearby yard capable to lift out my cat. Its not an mayday type emergency but also not something I would wait for weeks / months to take care of.
More so if you already have a leak into the engine room.


The upper seal of the Yanmar SD is not meant to be a permanent reliable seal. Its much thinner compared to the main seal, and its attached to the SD with two simple (but ridiculously expensive) steel bands holding it in place. Its just a last resort that can easily fail.


Replacement of the seal is expensive, around 500 in parts plus several hours of work (per engine). Its a good time to overhaul the SD, replace shaft seals, maybe bearings, have it sanded down and freshly coated, etc

EDIT: I have the service manual for the SD20 in case that is your SD model

[Capt. Ray]

Let's get some feedback from others then, I'll be curious. Our SD30s have huge thick diaphragm "boot" seals. We had a water alarm that had been going off for a year over 6,000 miles of sailing but little water intrusion into the engine room and when the saildrive was out it looked solid. I've read many discussions about this and the vast majority report the same.

Originally Posted by rabbi

If the alarm goes off I would look for a nearby yard capable to lift out my cat. Its not an mayday type emergency but also not something I would wait for weeks / months to take care of.
More so if you already have a leak into the engine room.


The upper seal of the Yanmar SD is not meant to be a permanent reliable seal. Its much thinner compared to the main seal, and its attached to the SD with two simple (but ridiculously expensive) steel bands holding it in place. Its just a last resort that can easily fail.


Replacement of the seal is expensive, around 500 in parts plus several hours of work (per engine). Its a good time to overhaul the SD, replace shaft seals, maybe bearings, have it sanded down and freshly coated, etc

[rabbi]

It depends...
If the leak comes from a failed main diaphragm its time to get worried in my view. As soon as it starts to crack it is likely to develop more cracks or fail badly.
Just like my exhaust hose: I fixed a small leak on passage, and just moving this brittle hose caused new leaks to pop up faster than I cold fix.


But of course there is the possibility to develop a leak without a cracking diaphragm. It could be a leak at the sealing joints between hull / seal / SD. In that case I would not be worried too much.

In fact we once experienced this after running into a huge pile (size of a house) of abandoned fishing net floating just under the surface. That incident slightly dislocated the SD and cracked the fibreglass under the SD and around the bolts. We had a smallish leak.
And this happened just weeks after replacing the main diaphragm, so the diaphragm was certainly OK.

[arsenelupiga]

would suggest to make engine room watertight. Especially if not changing seal immediately and even if you do.

Extra insurance.

[chris in SG]

Strange coincidence..

My yanmar SD20 saildrives were overhauled professionally one year ago and all the seals/boots were renewed. A few weeks ago, one alarm started sounding, at first intermittently and then continuously. I removed the alarm sensor cautiously and, sure enough, there was water in the chamber between the two seals, but no immediate flow. I sucked out the water with a thin tube and then used several wicks of twisted paper towel to remove the remaining water. Since then the alarm has not sounded again. It's clearly not a case of brittle rubber, and there has been no collision or rope around the prop, so it can only be either careless sealing around the lower boot on assembly or possibly some defect in the GRP hull itself which is allowing minor inflow around the saildrive aperture. Either way, it cannot lead to any catastrophic inflow and I'm reluctant to remove the saildrive to check, even though a haul-out is due soon..

[Ram]

I have the Sd20 sail drive and my boats in the water 6 months every year,the alarm went off about 5years ago and have still had no leaks, the boat was built in 2006.
Still looks excellent
Anyway I'm thinking about replacing it before I cross the Atlantic ...

[Perfect Ride]

When first looking at sail drives in 2014 I ran across a add-on that involved having a reserve oil tank high enough above the sail drive so the partial pressure forced oil OUT rather than let water in. Leaks were detected by watching the levels on the reserve. We ended-up sticking with shaft drives so I never further designed a solution, but might be an option if you had the parts to put one together and the leak was small.
I would call someone at Yanmar as a first step in any case.

[ggray]

Yes, I installed a header/expansion tank maybe 15 years ago, and think it's a very good thing to do. I wouldn't do without.

But the problem here is water leaking through the thick rubber sealing ring between the leg and the hull and entering the engine compartment.

I believe Yanmar recommends replacement every 7 years. I'm at 18 years now on two sail drives, and think my time may have finally come to replace one. There is no big leak, for sure, but I think there may be a small seepage.

The top rubber diaphragm, thin as it is, is little comfort, but the engine is behind a fairly watertight bulkhead, along with an upgraded bilge pump.

[Lucky]

Originally Posted by Perfect Ride

When first looking at sail drives in 2014 I ran across a add-on that involved having a reserve oil tank high enough above the sail drive so the partial pressure forced oil OUT rather than let water in. Leaks were detected by watching the levels on the reserve. We ended-up sticking with shaft drives so I never further designed a solution, but might be an option if you had the parts to put one together and the leak was small.
I would call someone at Yanmar as a first step in any case.

Do notdo this as you will get too high oil level in the saildrive. This is detrimental to the internals and the natural expansion of the gear oil during operation will have nowhere to expand but out through the seals!
Replace the seals is the only option!
Happy lead free sailing from Lucky

[ggray]

Originally Posted by Lucky

Do notdo this as you will get too high oil level in the saildrive. This is detrimental to the internals and the natural expansion of the gear oil during operation will have nowhere to expand but out through the seals!
Replace the seals is the only option!
Happy lead free sailing from Lucky

The oil will expand into the expansion tank, so I see no problem. The closed, unvented system repeatedly subjects itself to internal pressure or vacuum. Asking for trouble, IMO.

I installed these tanks about 15 years ago, and had no problems with the sail drives since.

I wish I hadn't said that!