Leaking shaft seal - anything more I can do?

[Poey50]

I had some 'professional' work done 15 months ago when we first bought our Sadler 32. This included a new Volvo-type shaft seal being fitted and the boat then relaunched by the yard. I don't think the seal was burped on relaunch and, knowing nothing about diesels, shafts and the like, it was a few months before I realised that needed to be done. During last season I had a dripping raw water pump (now fixed) so thought that was entirely responsible for salt water in the bilge but now I think the seal was probably beginning to drip when the engine was used. Having fixed the pump I then worked out early this season that there was dripping from the seal when the shaft rotated at usual running speed but not when the engine was running slowly. After a four week summer cruise the problem has worsened and today I found a steady drip with the engine off. Eek! I added some more Volvo grease but that made no difference so I've tightened the seal around the shaft with a jubilee clip. That stopped the dripping so I could leave the boat and sleep at night.

Obviously I'd prefer to avoid having to lift the boat until the end of the season. I'm a bit concerned that my temporary fix may make matters worse when I loosen the jubilee to run the engine. If not then I'll try to get through the next two months mopping up after running the engine and then replacing the jubilee when leaving the boat.

Two questions:
1. Do you think the compression of the seal by the jubilee will cause trouble by permanently distorting it?
2. Is there anything else I might do as a temporary fix?

The seal is a Sole Diesel Volvo-type rubber stuffing box Type A

 

[Tranona]

Nothing more you can do. If it is leaking it is because the lip seals have worn or are damaged. Doubt it is anything to do with not burping as if you don't burp it your ears will tell you in no uncertain terms. The purpose of burping is to expel air and let water flow through the fluted rubber bearing behind the seals, which in turn are lubricated by grease.

Sounds like you have a poor quality seal or the shaft is damaged. Suggest when you do replace it you use a genuine Volvo seal or a Radice, which is better as it has an air vent and a lubrication nipple. Both are made by the same company.

 

[MoodySabre]

It is possible for these to be changed whilst afloat. Not a job for the faint hearted but I know people who have done it more than once.
You could do it scrubbing posts for a safer option that avoids a lift out.
You will soon find out if distortion makes it worse. That might focus your mind.

 

[Poey50]

Doubt it is anything to do with not burping as if you don't burp it you ears will tell you in no uncertain terms.

That's useful to know ...

Sounds like you have a poor quality seal or the shaft is damaged. Suggest when you do replace it you use a genuine Volvo seal or a Radice, which is better as it has an air vent and a lubrication nipple. Both are made by the same company.

I've had my eye on a Radice. Unfortunately my stern tube may be too wide although it is possible that it tapers down a bit but I can't properly check until I've got the existing seal off.

 

[Poey50]

It is possible for these to be changed whilst afloat. Not a job for the faint hearted but I know people who have done it more than once.
You could do it scrubbing posts for a safer option that avoids a lift out.
You will soon find out if distortion makes it worse. That might focus your mind.

I've seen a video ... gulp.

I might consider the scrubbing post option to at least have a good look and inspect the shaft and properly measure the stern tube. Then I could put it back together, order a new seal and replace on another drying out. As you say I'll soon find out if the jubilee clip has bad side-effects and that may determine a course of action.

 

[Champagne Murphy]

What type did you have before the Volvo seal? I had the older stuffing type and over the years there had been some wear so the new Volvo seal is a tiny bit looser than it could be. If its too bad they only solution is a new shaft.

 

[Poey50]

What type did you have before the Volvo seal? I had the older stuffing type and over the years there had been some wear so the new Volvo seal is a tiny bit looser than it could be. If its too bad they only solution is a new shaft.

I believe it was a genuine Volvo seal (rather than this Volvo-type). The surveyor thought there were signs that it had been leaking so recommended it be changed. Definitely worth checking the shaft for wear though ...

 

[john_morris_uk]

I've no experience of the Radice but I've fitted PSS shaft seals to our current and previous boats and been entirely satisfied with them. Maintenance free too. Our boat had exactly the same problem as you describe when we bought her. Volvo seal but the shaft was worn and dripped. The PSS uses a S/S collar on the shaft pressing against a composite block to effect a seal so the previous wear on the shaft didn't matter. (The stainless collar is slid on the shaft and fixed in place with Allen key grub screws and has two 'O' rings inside it to seal.). Very easy to fit and I've always fitted them myself.

 

[skip50]

I've no experience of the Radice but I've fitted PSS shaft seals to our current and previous boats and been entirely satisfied with them. Maintenance free too. Our boat had exactly the same problem as you describe when we bought her. Volvo seal but the shaft was worn and dripped. The PSS uses a S/S collar on the shaft pressing against a composite block to effect a seal so the previous wear on the shaft didn't matter. (The stainless collar is slid on the shaft and fixed in place with Allen key grub screws and has two 'O' rings inside it to seal.). Very easy to fit and I've always fitted them myself.

Another vote for PSS.

 

[Gwylan]

A familiar story.

Bite the bullet and change to a Radice seal. One of the best things we ever did.
Had a succession of Volvo seals, installed by professionals, their term not mine, and a succession of sleepless nights over the ingress of water.

New Radice, I fitted myself and we have not looked back. Do not dread looking in the bilges and having to mop up the accumulated water.

 

[reeac]

Our Volvo seal lasted 11 years and I only got it changed because it was past it's stated lifetime. When it came out there were signs of slight wear on the lips but it never leaked. Now have a Radice which seems fine so far and the need no longer to burp is a small bonus.

 

[Pye_End]

Might be worth checking engine alignment. It is possible for a Volvo type seal to peg out in a season if the shaft is not centered on the stern tube.

If the shaft is worn, I wonder if it is possible to move the seal or the shaft a few mm to give it a chance on a different part of the shaft?

 

[Poey50]

I've no experience of the Radice but I've fitted PSS shaft seals to our current and previous boats and been entirely satisfied with them. Maintenance free too ...

I've thought about the PSS and I like the idea of not having to replace a damaged shaft (now or in the future) but not even the manufacturer claims they are maintenance free. There's also the possible problem of crevice corrosion and if they do fail they can do so catastrophically unlike the simpler lip seal types which slowly dribble to death. I understand they are very widely fitted and if properly done so and well looked after are, no doubt excellent pieces of kit, but ... Googling "problems with PSS shaft seals" is not a good thing to do before attempting a night's sleep. (Just tried it.)

This from a rescue and tow boat operator is interesting ... https://www.passagemaker.com/technical/dripless-shaft-seals

... and this gives a balanced summary of maintenance issues ... http://www.mysailing.com.au/news/the-care-and-feeding-of-dripless-shaft-seals

 

[Poey50]

Might be worth checking engine alignment. It is possible for a Volvo type seal to peg out in a season if the shaft is not centered on the stern tube.

If the shaft is worn, I wonder if it is possible to move the seal or the shaft a few mm to give it a chance on a different part of the shaft?

I did check engine alignment after fitting a new cutlass bearing over winter. I didn't take the shaft seal off though so it wasn't clear to me if it was central in the stern tube. I'll check for that and for the possibility of moving the wear point. Thanks for the suggestions.

 

[john_morris_uk]

I've thought about the PSS and I like the idea of not having to replace a damaged shaft (now or in the future) but not even the manufacturer claims they are maintenance free. There's also the possible problem of crevice corrosion and if they do fail they can do so catastrophically unlike the simpler lip seal types which slowly dribble to death. I understand they are very widely fitted and if properly done so and well looked after are, no doubt excellent pieces of kit, but ... Googling "problems with PSS shaft seals" is not a good thing to do before attempting a night's sleep. (Just tried it.)

This from a rescue and tow boat operator is interesting ... https://www.passagemaker.com/technical/dripless-shaft-seals

... and this gives a balanced summary of maintenance issues ... http://www.mysailing.com.au/news/the-care-and-feeding-of-dripless-shaft-seals

Any ill maintained item can give nightmares for a boat owner.

As the first article said, "However, from my perspective as a trawler owner and towboat operator, a brand new dripless shaft seal, properly installed, will do exactly what the manufacturer claims it will do: provide a vibration-tolerant, drip-free stuffing box. "

Perhaps I over egged it when I said, "maintenance free". I think that when compared with all the regreasing and adjusting of a traditional stuffing box, our PSS seal feels like it's maintenance free.

 

[Poey50]

Perhaps I over egged it when I said, "maintenance free". I think that when compared with all the regreasing and adjusting of a traditional stuffing box, our PSS seal feels like it's maintenance free.

That sounds fair.

 

[Heckler]

I had some 'professional' work done 15 months ago when we first bought our Sadler 32. This included a new Volvo-type shaft seal being fitted and the boat then relaunched by the yard. I don't think the seal was burped on relaunch and, knowing nothing about diesels, shafts and the like, it was a few months before I realised that needed to be done. During last season I had a dripping raw water pump (now fixed) so thought that was entirely responsible for salt water in the bilge but now I think the seal was probably beginning to drip when the engine was used. Having fixed the pump I then worked out early this season that there was dripping from the seal when the shaft rotated at usual running speed but not when the engine was running slowly. After a four week summer cruise the problem has worsened and today I found a steady drip with the engine off. Eek! I added some more Volvo grease but that made no difference so I've tightened the seal around the shaft with a jubilee clip. That stopped the dripping so I could leave the boat and sleep at night.

Obviously I'd prefer to avoid having to lift the boat until the end of the season. I'm a bit concerned that my temporary fix may make matters worse when I loosen the jubilee to run the engine. If not then I'll try to get through the next two months mopping up after running the engine and then replacing the jubilee when leaving the boat.

Two questions:
1. Do you think the compression of the seal by the jubilee will cause trouble by permanently distorting it?
2. Is there anything else I might do as a temporary fix?

The seal is a Sole Diesel Volvo-type rubber stuffing box Type A

Sounds like the seal is goosed. As T says, the fluted bearing part is lubed by water and the lip seals by grease. However, they can be fitted badly and the lip or lips inverted allowing leaks. There should have been a split plastic doofer with it that is placed over the shaft and inside the seal to protect the seal and hold the lips in place as it is slid down the shaft. I would grease that up and slide it in to the seal to assure that the lips are not inverted. I would then split the shaft coupling and check that the shaft is somewhere near lined up. Use a 6" rule as a straight edge. If it is way out of line then there is an answer to why it is now leaking. To the others who belittle the design, as others have said, they last for years without giving any problems.
As to professionals doing jobs on boats? Hah, I am a cynic and some of the jobs done by "professionals" hmm!
As to the now? Get it checked and fixed asap!
Stu

 

[Norman_E]

I think that if a Volvo seal has failed so new, either it was not greased and burped on installation, or more likely the shaft is scored from a previous seal so that it wears the new one quickly. If that is the case fitting a new seal is a waste of money unless either the shaft is replaced, or polished to remove any roughness. I changed my old Volvo seal for a Radice one and consider the latter to be a much better design because of its vent and greasing point.

 

[Poey50]

I think that if a Volvo seal has failed so new, either it was not greased and burped on installation, or more likely the shaft is scored from a previous seal so that it wears the new one quickly ...

I'll add to those a third possibility which is that the shaft is not central enough in the stern tube and there is too much concentric displacement. Although the engine alignment was good when I changed the cutlass bearing over the winter I didn't remove the seal (cutlass bearing was done with the shaft in situ) so didn't check on how well it was centred.

Thanks to all for the replies and suggestions - I feel ready for the challenge ahead. :nonchalance:

 

[superheat6k]

The Volvo 'Blackjack' seal has labia like lips the must face outwards, which is opposite to the orientation caused when sliding a shaft in, and if the lips are inverted inwards they will drip a lot. However VP provide a small split orange fitting sleeve. The idea of this is after the seal is fitted to grease it lightly then push / slide it into the end of the seal from inboard, which pushes the lips over to their correct orientation.

Using a slightly flattened MacDoanlds straw is very useful for getting the grease into the sealing lips.

BTW my preference is also PSS.