How long will this stern gland keep going.

[Moodysailor]

I replaced the 'Cuff' between the stern tube and the seal when I fitted our 'Orbitrade' version of the Volvo seal. It was still in very good condition, internally as well as externally. It was kept as a spare. I also moved the Orbitrade seal some eight inches further forward to improve access. Even Clyde the UrangUtang from 'Any Which Way But Loose' could not have reached the OE 'Squeeze a bit of string around the shaft' seal. Tools could not be placed on the adjusting nuts and turned either. I draw the line a knocking the bronze nuts round with a screwdriver!

Bringing it forward also allowed a fresh bit of unworn shaft to be the sealing area, and made it very easy for the annual lube injection. That should make rogerthebodger happy!

I recently successfully fitted a 70 year old master cylinder repair kit to a Land Rover. The rubber bits were fine, wrapped in special protective paper and in a cardboard box they were just as I remember getting them from the stores when an apprentice.

I obviously made sure of their condition before installing.

I have a 70 year old competition motorcycle. It uses bands cut from old inner tubes as 'bungys' fitted about 25 years ago. They are still fine. Some red rubber Czech 'Barum' Speedway inner tube bands, made from natural rubber, not synthetic rubber, fitted at around the same time are crumbling.

I agree, one must be prudent, but as one of the 20th centuries origonal recyclers in my long time business as a Veteran, Vintage and Classic Motorcycle restorer I have considerable direct experience of rubber and synthetic rubber bits.

Pic shows the extended seal. Note how tight access was before it was moved-and the rusty splash marks where the OE Bronze seal was leaking.

I get your point, and it sounds like you have good reason and experience to trust your own judgement. Also, I completely get your sentiment about the OE seal you replaced - one of the same reasons ours is now on the boat jumble pile. Nice job on your replacement.

I have worked in the marine industry over 30 yrs, and the last decade plus in the large commercial, offshore and defence side (prior to that in small commercial & leisure). In my job I deal with shelf-life issues on rubber components more than I should, and more than I want to - having generated what I feel is an unhealthy level of knowledge (gven my role) about a niche subject!

In my world, "fine" and "still working" are purely subjective and impossible to quantify, and therefore have no place. It's my own opinion, but I don't think that it is worth hanging on to a 17 yr old shaft seal when there is a new one ready to go. This is our hobby, where we spend our free time. It doesn't need to be, and shouldn't be a stressful experience, and I could not justify the peace of mind 'cost' for not replacing an old seal. A landrover, motorbike or something above the waterline is a different matter - if I can get out and walk home, or it isn't going to sink my boat or leave me needing to bail and get a tow then my advice leans much more towards "whatever works for you".

 

[Tranona]

I get your point, and it sounds like you have good reason and experience to trust your own judgement. Also, I completely get your sentiment about the OE seal you replaced - one of the same reasons ours is now on the boat jumble pile. Nice job on your replacement.

I have worked in the marine industry over 30 yrs, and the last decade plus in the large commercial, offshore and defence side (prior to that in small commercial & leisure). In my job I deal with shelf-life issues on rubber components more than I should, and more than I want to - having generated what I feel is an unhealthy level of knowledge (gven my role) about a niche subject!

In my world, "fine" and "still working" are purely subjective and impossible to quantify, and therefore have no place. It's my own opinion, but I don't think that it is worth hanging on to a 17 yr old shaft seal when there is a new one ready to go. This is our hobby, where we spend our free time. It doesn't need to be, and shouldn't be a stressful experience, and I could not justify the peace of mind 'cost' for not replacing an old seal. A landrover, motorbike or something above the waterline is a different matter - if I can get out and walk home, or it isn't going to sink my boat or leave me needing to bail and get a tow then my advice leans much more towards "whatever works for you".

In all your years of experience, have you ever seen a Volvo type seal fail catastrophically because of splitting or degradation of the rubber? The design has been in extensive use for over 40 years and I have never seen a report of failure in this way - only wear of the lip seals or grooving of the shaft. This is almost always due to lack of regular lubrication (once a year).

 

[Moodysailor]

In all your years of experience, have you ever seen a Volvo type seal fail catastrophically because of splitting or degradation of the rubber? The design has been in extensive use for over 40 years and I have never seen a report of failure in this way - only wear of the lip seals or grooving of the shaft. This is almost always due to lack of regular lubrication (once a year).

No, but I know well enough not to fall into the confirmation bias trap. I have changed plenty, and it's easy enough to tell the difference between a new one and one that is 10+ years old (aside from the grease and dirt ). Almost all of the VP seals I saw were changed frequently enough - the cost point has always been low enough that it works out to a quid-fifty per year or something over a 10yr period, so why would you risk it and not do it...?

If the question is "how many stern seals of all types have you seen split at the rubber" then the answer is, unfortunatly, too many, aside from a couple of isolated cases, all were aged. As above, one of the great advantages of the VP seal (and version of) is that they are affordable and easy to change (relatively speaking) and therefore tended to get changed before there is breakdown of the material.

When a stern seal fails, it's a huge pain. Assuming it's identified quickly enough and there is enough stuff on board to stem the leak, the shaft cannot be turned, meaning it's difficult if not impossible to get into a safe port unassisted. In almost every case i've seen, the failure has happened when the engine was running, and the resultant centrifugal waterfall has had various impacts from a huge mess to a new engine due to water ingestion. I have, sadly, seen boats that have come in on lift bags after sinking as a result of stern seal failure that wasn't able to be stopped or was already too far gone and the bilge pump couldn't keep up.

As I said, it's a personal choice. Just not one I would risk, or advise risking for £1.50 per year.

 

[snowbird30ds]

or advise risking for £1.50 per year.

So as mine cost £175 each I should be OK for 116 years, result!

 

[Plum]

In all your years of experience, have you ever seen a Volvo type seal fail catastrophically because of splitting or degradation of the rubber? The design has been in extensive use for over 40 years and I have never seen a report of failure in this way - only wear of the lip seals or grooving of the shaft. This is almost always due to lack of regular lubrication (once a year).

Completely agree, very durable and no evidence of catastrophic failure because of splitting or degradation. Others who mention failures appear to be referring to prop-shaft seals in general.

 

[Tranona]

If the question is "how many stern seals of all types have you seen split at the rubber" then the answer is, unfortunatly, too many, aside from a couple of isolated cases, all were aged. As above, one of the great advantages of the VP seal (and version of) is that they are affordable and easy to change (relatively speaking) and therefore tended to get changed before there is breakdown of the material.

You are changing the question - and you are right, other types of seals fail BECAUSE the rubber they use does degrade - but it is completely different from the Volvo type, not only the material but the function it fulfils.

The beauty of the Volvo seal is that the rubber does not degrade and fail. The failure is due to wear of the lip seals which is normally very slow and obvious allowing plenty of time for safe replacement.

 

[dgadee]

Am I right in thinking that, long before the rubber is ready to fail, it will change texture, becoming stiff? If so, I'd keep an eye on it, and change it at the next lift-out if that happens.

Because we're on a drying mooring, I'd fit the Obitrade version, as it has a vent, so doesn't have to be burped when it dries out.

Problem with those is when you go into reverse (setting an anchor, e.g.) water floods up the pipe. It took me a while to work out where the salt water in the compartment was coming from - I was always at the helm rather than looking at the engine.

 

[Tranona]

Problem with those is when you go into reverse (setting an anchor, e.g.) water floods up the pipe. It took me a while to work out where the salt water in the compartment was coming from - I was always at the helm rather than looking at the engine.

The pipe should go well above the waterline to prevent that. Never had that problem with the 2 boats I had with the vented seal.

 

[dgadee]

The pipe should go well above the waterline to prevent that. Never had that problem with the 2 boats I had with the vented seal.

Yes, my pipes went above the waterline but maybe not enough.

 

[snowbird30ds]

Tee into the raw water pipework and use it as a water feed instead of a vent, still best to burp them after drying though as air can be trapped depending on shaft angle.

 

[Moodysailor]

You are changing the question - and you are right, other types of seals fail BECAUSE the rubber they use does degrade - but it is completely different from the Volvo type, not only the material but the function it fulfils.

The beauty of the Volvo seal is that the rubber does not degrade and fail. The failure is due to wear of the lip seals which is normally very slow and obvious allowing plenty of time for safe replacement.

Yes I changed the question, to highlight the point I was trying to make. You are incorrect in your comment, all rubber degrades and fails, there is none that doesn't. It's an inherent reality with the material.

My point was that, if Volvo type seals were left as long as other rubber components, they would fail - it's inevitable. My opinion as to why I haven't seen any fail is that I have never seen one in service for 20+ years. Manufacturere advice, the advice of trustworthy engineers in the industry, and the price point means they are often changed long before the rubber fails. It seems to be the preserve of a view on this forum to ignore facts and and pick fights from an anecdotal position.

I am fully aware that the shaft contact areas are the high wear point, this is no different with any seal.

 

[Moodysailor]

Completely agree, very durable and no evidence of catastrophic failure because of splitting or degradation. Others who mention failures appear to be referring to prop-shaft seals in general.

Correleation is not causation. All rubber degrades eventually, there is none that doesn't.

I would suggest the reason that there isn't evidence of faliure is that they are well made and durable, and are replaced before failure. Other stern seal types rarely, if ever have the rubber elements replaced.

 

[rotrax]

Problem with those is when you go into reverse (setting an anchor, e.g.) water floods up the pipe. It took me a while to work out where the salt water in the compartment was coming from - I was always at the helm rather than looking at the engine.

Your pipe was too short perhaps?

Our vent pipe-see pic in post#20- is at least a metre above the waterline and is 3/16" I/D.

Our engine is a Yanmar 4JH4-HTE 110HP Turbo Diesel swinging a 21x17 R/H Prop. It is a heavy boat, needs lots of astern power to stop it. Also needs a bit of grunt to dig the hook in.

Our bilge-apart from the bilge sump, which gets rainwater from the keel stepped mast-is as dry as a Nuns Crutch.

 

[dgadee]

Tee into the raw water pipework and use it as a water feed instead of a vent, still best to burp them after drying though as air can be trapped depending on shaft angle.

On a drying mooring? Not feasible.

 

[Tranona]

Yes I changed the question, to highlight the point I was trying to make. You are incorrect in your comment, all rubber degrades and fails, there is none that doesn't. It's an inherent reality with the material.

My point was that, if Volvo type seals were left as long as other rubber components, they would fail - it's inevitable. My opinion as to why I haven't seen any fail is that I have never seen one in service for 20+ years. Manufacturere advice, the advice of trustworthy engineers in the industry, and the price point means they are often changed long before the rubber fails. It seems to be the preserve of a view on this forum to ignore facts and and pick fights from an anecdotal position.

I am fully aware that the shaft contact areas are the high wear point, this is no different with any seal.

You are still missing the point. The rubber used in bellows is very different from that in the seals. It is also under stress and failure can be catastrophic. Plenty of reports here of Volvo seals 15-20 years old with no sign of degradation and never seen any reports of failure due to degradation. Of course the rubber may eventually degrade, but there is no data (only guesswork) on time scales.

Few are likely to be in service for really long periods (30+ years) because either the lip seals will wear, or they will be replaced during an engine change for example.

Remember the OPs question was should he replace his unit. No sign of leaking, from the photo properly installed in a clean dry environment. Absolutely no danger of it failing therefore no need to replace. Just as many have said, keep it lubricated and inspect periodically for signs of leaks.

 

[Dogone]

My PSS failed at 8 years due to stiffening of the bellows and nearly sank the boat. The manufacturer recommends changing at 7/8 I think. Maybe this doesn't apply to a Volvo gland, but be sure about that as this is a failure that can do a bit more than ruin your day.

 

[dgadee]

My PSS failed at 8 years due to stiffening of the bellows and nearly sank the boat. The manufacturer recommends changing at 7/8 I think. Maybe this doesn't apply to a Volvo gland, but be sure about that as this is a failure that can do a bit more than ruin your day.

I don't like those fancy, expensive ones at all. Volvo seals are simple and will drip to tell you there is a problem. On my Dehler, 1200 hours of engine in 10 years and still fine.

 

[rotrax]

You are still missing the point. The rubber used in bellows is very different from that in the seals. It is also under stress and failure can be catastrophic. Plenty of reports here of Volvo seals 15-20 years old with no sign of degradation and never seen any reports of failure due to degradation. Of course the rubber may eventually degrade, but there is no data (only guesswork) on time scales.

Few are likely to be in service for really long periods (30+ years) because either the lip seals will wear, or they will be replaced during an engine change for example.

Remember the OPs question was should he replace his unit. No sign of leaking, from the photo properly installed in a clean dry environment. Absolutely no danger of it failing therefore no need to replace. Just as many have said, keep it lubricated and inspect periodically for signs of leaks.

Exactly. A truism I like and abide by is 'True Knowlege is the Product of Direct Experience'.

Many on here do not know how these Volvo type seals work. They are so simple and work on the laws of Physics. The two lips are quite long-about 10mm-and are very soft and flexible.

The seal is purely from water pressure pressing the rearmost seal into contact with the shaft. The front seal is the 'Belt and Braces' fallback should the rear seal fail.

Put your arm in a poly bag, stick it two feet into the oggin-you will get the idea! Very simple, no mechanical stuff involved.

Vyv Cox website has a full breakdown and an exploded diagram showing the integral bearing area too.

I for one shall continue to use them within the sizing/availability constraints.

The first one I fitted, on a GibSea 96, required an alloy sleeve epoxied to the stern tube to bring the diameter up to what was available. I knocked one up from an alloy scaffold tube. Still in place and working well today, over 20 years later. It HAS had a new seal!

 

[Moodysailor]

You are still missing the point. The rubber used in bellows is very different from that in the seals. It is also under stress and failure can be catastrophic. Plenty of reports here of Volvo seals 15-20 years old with no sign of degradation and never seen any reports of failure due to degradation. Of course the rubber may eventually degrade, but there is no data (only guesswork) on time scales.

Few are likely to be in service for really long periods (30+ years) because either the lip seals will wear, or they will be replaced during an engine change for example.

Remember the OPs question was should he replace his unit. No sign of leaking, from the photo properly installed in a clean dry environment. Absolutely no danger of it failing therefore no need to replace. Just as many have said, keep it lubricated and inspect periodically for signs of leaks.

I'm not missing the point, you made an assumption. I have seen failures from straight rubber connectors, not just bellows types. Rubber will degrade in time, there is no "may"

You continue to use anecdotes to argue against knowledge. That's fine, but don't call for help if you ignore good wisdom and later have a problem.

 

[dgadee]

With Volvo seals you need to be really careful inserting the shaft - use the bit which comes with the seal. Club member had a new engine put in and the nit who was paid to do it obviously didn't take care. Seal dripped soon after. I was shown the old one and the seal bearing parts were clearly damaged.