Stuffing box problem

[Martin Sigge]

Good Day fellow Sailors,

my prop shaft stuffing box is leaking. When I took off the hose that should bring oil for lubrication, water came up there too and increased the leakage.

Does anybody have any experience of this?

Can I do something when she's in the water, or must it be done on the hard?

All comments are most welcome

[Ballsnall]

Originally Posted by Martin Sigge

Good Day fellow Sailors,

my prop shaft stuffing box is leaking. When I took off the hose that should bring oil for lubrication, water came up there too and increased the leakage.

Does anybody have any experience of this?

Can I do something when she's in the water, or must it be done on the hard?

All comments are most welcome

That looks more like a lip seal than gland packing so I don't think it's a stuffing box. Do you have any info on the type/brand?
Is it a high speed shaft?

[Martin Sigge]

No, I don't know the type/brand. I'm sure you are right about the lip seal, I just didn't know the correct term. The shaft is very low speed. It's driven by a Volvo Penta MD2B via a reduction gear. The diameter is 25 mm.

[Ballsnall]

Ok, its very unusual to have an oil feed to a low speed shaft seal, they usually have water feed for high speed due to heat but on low speed shafts like you have it is just to bleed the air out on installation.

It is possible to replace the shaft seal in water. Just tape a plastic bag around the shaft and stern tube behind the prop to slow down the water ingress.

You might be better of just buying a new dripless style shaft seals and just doing a quick change out.

[Martin Sigge]

Massive thanks, Ballsnall :-)
Do you know of any special brand or model that you could recommend?

[Martin Sigge]

About the warped seal in the picture; I wonder if I dare try to push it back in position again, or if that could potentially make the leakage worse? I think the reason for the seal having moved could be water that froze in the winter when she was on the hard.

[Ballsnall]

There are quite a few on the market these days, PSS & Lasdrop also the Tides Marine SureSeal. I don't have any direct experience with the difference brands but they are all very similar in design and all work very well.

I think the PSS might be the most popular.

[Searles]

Looks like a water cooled lip seal ,there should be a C clip holding the seal in place ,these were commonly used in speed boats in an outher era ,a pss will solv the problem ,plus can still use the water feed .⛵️⚓️

[Ballsnall]

Originally Posted by Martin Sigge

About the warped seal in the picture; I wonder if I dare try to push it back in position again, or if that could potentially make the leakage worse? I think the reason for the seal having moved could be water that froze in the winter when she was on the hard.

It might work but being a lip seal they usually wear a groove in the shaft especially when used in water with high sediment and the seal will most certainly be worn but if your correct about the freezing then probably worth a try.

If it was on the hard he could pull the unit and replace the seal then change the bellows length to relocate the sealing area on the shaft or sleeve the shaft, but lip seals are so yesterday, for a couple hundred bucks I'd go with the drip seals carbon face seal.

[bil56]

I have got a PSS for many years, very satisfied
(shaft 25mm, Yanmar 3YM20)

[Jamme]

You may want to give a read to this thread. It’s Beneteau specific, but your setting appears similar. If indeed it is similar, you may need to ensure continuous flow of water to ensure lubrication.
Good luck.

https://www.cruisersforum.com/forums...ff-274050.html

[SVQuestOfPaget]

I dealt with this same lip seal arrangement on a folkboat last year - had been completely dripless for years, then one day I found the bilge scarily full of water. I tried several short-term fixes while on the water that didn't work, and replacement while in the water wasn't going to be an option.

The day we hauled the boat, I carefully loosened the hose clamps and gently slid the entire unit up the shaft 1/8", and the leaking stopped entirely. I think the lip seal found "fresh" propeller shaft to seal against - maybe it would have kept sealing for another few years?? Given how difficult it was to access in this particular boat, I opted for a traditional stuffing box replacement. I use a PSS shaft seal on our bigger boat, where access and inspection is easier.

[jordanbigel]

This does look like the same shaft seal I use - it's an oil filled system with 3 lip seals (2 in back, one in the front) - https://norscotshaftseal.com.

If you have water coming in when you remove the hose from the nipple, then the rear seals are shot and are leaking badly. In the photo, the front seal also looks distended as well, it should be flush not sticking up on one side like in the photo.

The hose from the nipple goes to an oil reservoir with about 1pint transmission oil (ATF type F or Dexron).

I choose this seal because when my boat was being refit in Seattle, I was unable to find any other dripless seal which fit in my shaft tunnel which is very very narrow. Norscott is made in WA state and is very popular in that area so the guys at the yard suggested it to me, and since it fit, I went with it. I've had it for over 20 years and I find I have to change the lip seals every 6-8 years.

I don't think this can be fixed without hauling the boat and replacing all 3 lip seals. The seals are easily available (made by Parker) and the Norscott web site has all the info on sizes, etc, (if it is a Norscott).

[Martin Sigge]

Thanks jordanbigel, that's very good info :-) The day before yesterday I refitted the oil hose, and water immediately rose to the boat's water level. I filled the hose with engine oil, which is all that I had available, and the oil pushed the water back into the seal box, and back to the sea, I suppose (where else?). The leaking stopped (more or less) almost instantly. There is no container at the top, the hose ends without anything connected, just naked, so the quantity of oil was only a few cl.

Yesterday morning I started 6 hours of motoring. A small leakage is still there when moving. I could not measure it underway, but I estimate it to be 0,5 - 1 L totally over the 6 hours. The leakage when I stopped was very small.

This morning I took a closer look and found that the level in the hose was back to the outside water level, and it looks as if what's left in it is a water/oil emulsion. I filled the hose again, and the water/oil slurry moves very slowly downwards. So I conclude that what leaks out of the oilfilled hose enters the sea, but not the bilge. At the same time something like a teaspoon of clear water has entered the bilge (over 30 minutes or so) This surprises me a little, but since DAX gets up on the hard within a few weeks, I feel that can live with the problem until then.

So, many thanks to all of you guys who have contributed with valuable advice. This is a great forum!!

/Martin

[jordanbigel]

Originally Posted by Martin Sigge

Thanks jordanbigel, that's very good info :-) The day before yesterday I refitted the oil hose, and water immediately rose to the boat's water level. I filled the hose with engine oil, which is all that I had available, and the oil pushed the water back into the seal box, and back to the sea, I suppose (where else?). The leaking stopped (more or less) almost instantly. There is no container at the top, the hose ends without anything connected, just naked, so the quantity of oil was only a few cl.

Yesterday morning I started 6 hours of motoring. A small leakage is still there when moving. I could not measure it underway, but I estimate it to be 0,5 - 1 L totally over the 6 hours. The leakage when I stopped was very small.

This morning I took a closer look and found that the level in the hose was back to the outside water level, and it looks as if what's left in it is a water/oil emulsion. I filled the hose again, and the water/oil slurry moves very slowly downwards. So I conclude that what leaks out of the oilfilled hose enters the sea, but not the bilge. At the same time something like a teaspoon of clear water has entered the bilge (over 30 minutes or so) This surprises me a little, but since DAX gets up on the hard within a few weeks, I feel that can live with the problem until then.

So, many thanks to all of you guys who have contributed with valuable advice. This is a great forum!!

/Martin

I think your analysis is correct. I have had the outer seals fail before also and the symptoms you describe are the same as what I saw. I think you can go a few weeks before addressing this as long as you try to keep the system full of oil.

I don't understand why the hose is not connected to a reservoir, like the one in the photo - you should fit one when you replace the lip seals.