PSS shaft seal bellows age

[North Baltic sea]

To see whether there is one experience or knowledge?

My NT 37 have shaft line is PSS seals, how often you have exchanged the bellows rubber, the recommendation is for six years. PSS bellow just had a birthday party for 7 years, it looks like new outsides, is it worth the change or wait?

 

[Irish Rambler]

All I can say is that I have exactly the same on my boat and fitted it 12 years ago and still looks perfect and has never given any problems.
The carbon face is only slightly worn and the bellows look and feel still perfect.
Brilliant piece if kit.

 

[psneeld]

I have seen one 14 years old on a 26 foot Shamrock in the assistance towing business and still going.....with only carbon seal replacement....

Not sure I would let it go that long on my personal boat.

If flexible and looking good.....it's a calculated risk to keep going on it.

 

[jleonard]

A few years ago a friend who was on a mooring, had one fail due to age. I'm guessing it was at least 10 years old.
His bilge flooded, eventually ruining his tranny, alternator, starter. I say eventually because it took a few years for the effects of the salt water to do it's damage.
Prevention is your friend here.

 

[O C Diver]

I did mine on the charter boat after 10 years and around 3,500 hours. Compared to the new one, it had lost some of its spring but the material was still strong. No signs of cracking.

Ted

 

[Gordon J]

I am sure that mine are original to my 2003 Ocean Alexander 456. The Bellows are still flexible with no cracks. The carbon face is a quarter to three-eighths inch thick. I can still tighten in the Bellows enough to keep the water out.

I am guessing that I am good for at least another 2 to 3 years.

Gordon

 

[sunchaser]

Mine came out after 12 years looking near new according to the yard that replaced them. A shaft zinc collar is in place to prevent any movement.

On a separate note, thoughts on Tides seal for leaky rudder packing would be appreciated.

 

[psneeld]

Jay Leonard shows that while failure might not happen when expected, but if it does....the outcome is not usually good.

 

[twistedtree]

Is there any sort of test or inspection that could be applied? For example, I'm wondering if some shoving and flexing of the bellows while watching for drips might not be a way to detect cracks that are starting to develop? The risk of course is that your shoving actually stimulates a problem, but if it does, at least you are there to see it and take action. But I generally lean towards trying to stimulate problems rather than letting them creep up on me.

 

[Bruce B]

I believe that PSS has used a couple of different materials for their bellows.
I may remember this incorrectly but I think the early bellows material had problems with taking a set and loosing tension on the seal face.
I remember talking to their rep at the time during a boat show who recommended replacement regularly for this reason. Had to be 10 or 12 years ago...
Bruce

 

[Mach_cat]

Pss in the installation says not to ozone generators on board with their seals. Just a warning there.

 

[sunchaser]

Jay Leonard shows that while failure might not happen when expected, but if it does....the outcome is not usually good.

Yup, $hit happens.

Not knowing any details in Jay's case but generally an untended moored vessel can have all sorts of problems possibly leading to a gotcha. The thread a few weeks ago on hoses is a good starting point for incipient failure awareness. My insurer has some interesting stories on moored vessels. Surprisingly to me, rain water and plugged deck drains lead to lots of damage. Even on the hard where leveling is not done correctly.

Yes boats can make water, for oh so many reasons. The trick is to catch it early as Tree says.

 

[Jeff F]

I asked a manufacturer's rep at a boat show this year about the six year replacement recommendation. Mine is seven and looks to be in perfect shape. His advice was to leave it alone for a few more years with periodic inspection.

 

[Ski in NC]

Go wrestle it a little bit, flexing it. If the material is deteriorated, it will show cracks, feel stiff, feel mushy, etc. If it feels good, I'd probably roll with it. If it falls apart and starts leaking, it is time to change it!!!

Lifespan of elastomers is a crapshoot.

 

[twistedtree]

Speaking of maintaining seal pressure, another thing to check are the set screws that lock the rotor to the shaft. The should be installed with blue loctite. Then a second set screw should be installed on top of the first to lock it in place, much like stacked nuts on a bolt.

I discovered that mine not only were missing the stacked lock screw, but that no loctite was used and the set screws were only finger tight.

 

[dhays]

The PSS on my sailboat is 11 years old and looks great. The one on my NP is 6 years and also looks great. When/if I have to haul the boat for some other I will likely change out the PSS seals just as a preventative measure.

 

[Carolena]

We have the same set up on our Nordic Tug. We replaced it the first year we owned the boat, and it was about 10 years old at that point. The rubber was OK, no cracks, but had lost some of its flex. It is the flex in the rubber that keeps the carbon and steel collars together. BTW, make sure to check the large hose clamp that attaches the bellows to the shaft log. It had loosened on our boat, which caused the belows to rotate, resulting in the cooling water hose being crimped. With no cooling water, we overheated the shaft, bearings, etc. We got lucky and were able to do the repairs in the water, but the overheating experience while underway is not something I'd want to go through again (think smoke and lots of really noxious fumes).

 

[Chrisjs]

Our experience is similar to others. Our PSS was 9 years old when replaced on a Selene 47. It looked perfect when removed. I think they last a good long time on slow turning trawlers, not so sure about go-fast boats!

 

[psneeld]

Sand and silt environment as well as misaligned engines probably do more damage than just faster turning engings, but that too will influence lifespan.

 

[Nomad Willy]

I replaced my bellows after 8 years.
Just because.

 

[North Baltic sea]

Thanks for all the replies.


It would appear that the bellows may take a few more yars, my Nt is only about 600 hours running, the risk is, of course, mine.


A nice cruise for everyone!

 

[stone beach]

Thanks for all the replies.

It would appear that the bellows may take a few more yars, my Nt is only about 600 hours running, the risk is, of course, mine.

This issue is more related to age than operating hours.
Agree with Ski, if its still flexible its probably ok

 

[garrobito]

After read this post went down the engine room to check mine.. seems stiff to me.. another thing to replace on the next haul out...

 

[Chrisjs]

Hard durometer, thick "rubber", and compression make it difficult to determine whether bellows is hardened because of deterioration. Look for micro-cracks. Might be easier to tell if compression is released next time out of water.

 

[sunchaser]

A good bright LED light will illuminate the PSS quite nicely for a visual. Yes, the bellows will be "stiff" since the material is designed for below the waterline use. Even when new they will appear stiff to some.