S2 11.0A S-drive seal leak

[RumRonrrr]

Hello Everyone,

I have an 1981 S2 11.0A, and the oil bilge enclosure is exhibiting multiple leaks. My understanding is there is not supposed to be water in this enclosure (it supports the engine mounts and creates an "Oil Bilge" below the engine.

Does anyone know how water can be getting into this area?

Thanks,
Ron

[DougR]

There are three basic ways water can be leaking into the "oil bilge" area.

1. The engine has a water leak somewhere in its cooling system, and the water is dripping into the oil bilge. If this is the case, careful observation will find it.

2. The saildrive leg sticks down thru the engine bed and out the bottom of the hull, and the area surrounding the leg inside the hull is filled with water. This area is sealed from the interior of the hull with a heavy diaphragm which is clamped down onto the engine bed with a metal clamp ring. If the hold down action of the ring has failed, or the diaphragm has started to leak, water can leak in and run into the bilge. Again this should be visible by careful examination around the seal, particularly in the area of the flywheel housing.

3. When the engine bed is shaped and glassed to the hull, the bed is glassed to the hull around the exterior perimeter of the bed, around the interior perimeter of the oil bilge, and around the interior perimeter
of the cylinder thru which the saildrive leg protrudes. If a crack or de-lamination of the glass around the cylinder occurs, this will allow water to enter into the area below the bed, and this water might be working its way into the oil bilge.

My feeling is that the order of probability of one of these problems occurring is highest for #1, and lowest for #3. But, never say never.....

Attached are a couple of pages from a Volvo installation manual which might make my description of the glass work more understandable.

DougR

[RumRonrrr]

This is great info DougR! Thanks for the explanations and diagrams.
The water is getting into the enclosure and then from there leaking into the oil bilge, so your "#3" looks like the option that is currently happening.
Water is also dribbling up through one of the 2 missing bolts in the ring compressing the diaphragm seal.
Questions:
1) Are these 2 bolts supposed to be not installed?
2) Should I use a torque wrench to make sure the rest of the bolts are the correct tightness?
3) Do you suggest removing the water per your diagram (drill into the cavity) now while the boat is in the water and then finding the leak in the s-drive cylinder when on the hard?

Thanks again for your comprehensive response!!!
Ron


Sent from my iPhone using Cruisers Sailing Forum

[DougR]

Hi Ron,

The engine bed that is installed in your boat might be a factory VP bed, or it could be something that was made by S2. Many builders make their own engine beds and glass them into the hull, or sometimes they incorporate the bed into an inner liner, and things like that. I'll comment as though your bed is a factory VP piece......


1. When VP makes the engine bed, they glass a small metal insert (2" X 2") into the bed in the area where the clamp ring bolts are, and they drill and tap into this plate to act as a nut for the bolt. Sometimes these drilled holes penetrate all the way into the cavity beneath, and normally that is not a problem. In any event, all of the bolts should be used, and I recommend installing bolts in the empty holes. Of course you might find that someone in the past has stripped the threads, and that's something to deal with at a later time.

2. Before I would torque the remaining bolts, I would try to fit new bolts into the currently empty holes and see what the threads in those holes feel like. If they are stripped, who knows the condition of the remaining holes. As the boat is in the water it might not be wise to
tempt fate. As I recall, the currently used bolts are 8mm X 1.25 thread, but I'm not sure what they used in the MD11 and MD17 days.

3. I don't think I would be drilling that ventilation hole now while the boat is in the water. Doing so might allow a larger direct leak into the boat. In fact, I'm not so sure that the hole is required at all. Plenty of beds have been installed without one.

DougR

[RumRonrrr]

This makes sense DougR, thanks again.

So my plan while on the water is to:
1. Fit bolts into the two missing holes in the ring
2. Stop the leaks in the enclosure with Marine Tex for now

Once on the hard:
1. check out where the leak is in the S-drive well and repair
2. Drain the water out of the oil bilge enclosure (there are currently 3 patched holes in the enclosure as shown in the diagram, from past owners)

Does this make sense and do you know the type of glue used to hold the "cloth" barrier over the opening to the well, onto the hull?

Ron


Sent from my iPhone using Cruisers Sailing Forum

[DougR]

Ron, Your plan sounds good to me.

For info on bonding the fairing strip to the hull check out the thread " S drive rubber collar".....its in the propellers and drive systems area.

DougR

[RumRonrrr]

I'll check out that link. I was going nuts trying to find info on what was going on with the S-drive/oil bilge housing. I really appreciate all the help you have provided!!!

Thanks a lot DougR


Sent from my iPhone using Cruisers Sailing Forum