Dripless shaft seal owners beware.

[Wotname]

^^ Crikey, that's scary yet I have often had these seals sit for many many months without this issue - I can only think the problem has been solved. I've never seen that warning but then again, I have never looked!

[pbmaise]

PYI PSS owner here

I operated with it ten years no maintenance and previous owner for eight.

When I first purchased vessel "grub" screws slipped on shaft on very first trip and required retightening. And yes that was a flood of water. Therefore, if you purchase a vessel with one recommend checking if these screws are tightened correctly.

For several years it had very slow drop whenever running engine which got progressively worse at one point. About one bucket of water every five hours.

One year rate got pretty bad and I discovered very fine fishing line sticking from my cutlass bearing. I pulled it out and it appears to have been keeping seals open. Rate slowed.

Once in a while it spits some black water that leaves a stain sprayed in a pattern thrown by the momentum of the shaft. I believe this is to be carbon and the seals are self-polishing themselves after something separated them.

On last trip rate was very pleasantly zero and it was actually dripless as advertised.

This product reminds me own people say stainless steel just stains less and isn't stain free.

Bellows still worked well and looked great after 18 years. Further other than one slip product never needed maintenance or repair. It just leaked.

[pbmaise]

Originally Posted by Dev0n60

I have been the very unlucky person to have the PSS nitrile bellows literally disintegrate. It was completely my fault..... at the time (1993-4) there was no concerted effort by PYI (the vendor) to tell people they sold the units to, how to maintain them.... I replaced the original Hypalon bellows in 1999 because the Hypalon developed what the manufacturer called 'memory' and no longer kept adequate pressure against the rotor.... leaking....
The newer Nitrile bellows was fine until one day after coming back to the boat after being away for a few months, I started the engine and put it in gear in the berth to charge the batts and load up the engine. Almost immediately my bilge alarm started shouting at me!
Inspection revealed that the nitrile bellows was shredded. Water was pouring in thru the stern tube! The one hole in a boat that one cannot stick a bung into.
Trying to not panic, I quickly grabbed some material I use for creating moulds: 'Poly Vinyl Siloxane Putty'..... I mixed the part A & part B together, grabbed my mask, hopped over the side and stuffed the putty around the shaft at the point where it entered the stern tube. Viola! The in rush of water completely stopped.
This worked so well that we motored across Auckland Harbour to Orams and hauled the boat without a drop coming through. It took a good 45minutes to dig the putty out once hauled. This putty comes in various consistencies and once set, is quite hard/robust.

So.... the problem I now understand and which PYI now clearly warns people of: after sitting for a prolonged period of time (???) the rotor and carbon ring will form a tight bond to each other. So tight that the action of putting the boat in gear without first breaking the bond can cause the nitrile to sustain a significant amount of torque and fall apart. DO NOT DO THIS!!! These days, if I do not run the engine for more than a week, I simply take a mallet and LIGHTLY tap the meeting point of the Rotor and the Carbon. This has always been enough to break the two apart from each other.

I have also noted the PYI have significantly 'beefed' up the spec/gauge on the nitrile they supply these days compared to earlier versions

Very interesting. This post may explain why on my very first trip the set screws failed. The previous owner had not engaged forward for potential months. I am not entirely clear where this tap is performed. I understand it to be different than burping.

Further isn't this seal surface contained within the bellows?

Note: In previous post I forgot when I said no maintenance about the stainless steel hose clamps. These had to be replaced about every two years.

I am also wondering now if I had so many years of dripping because after the bellows slipped the guys that came to my rescue and retightened the screws did so incorrectly.

I heard of the. Sand paper solutions however my PSS only dripped when engine was running or under sails.

I guess fear of causing a greater problem held me back from trying. Improper pressure never occurred to me.

[geoleo]

Originally Posted by Scaramanga F25

I just do not trust this type of seal. I never have had a problem with the traditional stuffing box type in 41 years. You can even repack in the water.

AMEN!

[MicHughV]

my Beneteau 432 comes standard with a shaft seal.
It is not a standard stuffing box nor is it a PSS shaft seal, but some other kind, difficult to describe here, but it has a very stiff solid rubber outer sleeve with some kind of inner sleeve and has a water injection tube about halfway along it's length.
I believe that tube assists in keeping the ring around the prop shaft cool.
It's some kind of French design.
Whatever it is, it works just fine.

[GILow]

Originally Posted by pbmaise

I am also wondering now if I had so many years of dripping because after the bellows slipped the guys that came to my rescue and retightened the screws did so incorrectly.

The manufacturer is absolutely emphatic on this point. Do NOT re-tighten the grub screws. Throw them out and start again.

Secondly, these seals should not drip. There are VERY explicit instructions for setting the compression on the bellows.

Finally, ten years is the recommended maximum age for these seals. By your description you had a seal that was 18 years old. That's just plain crazy.

To be blunt, you really should read the instructions.

[Wotname]

Originally Posted by GILow

The manufacturer is absolutely emphatic on this point. Do NOT re-tighten the grub screws. Throw them out and start again.

Secondly, these seals should not drip. There are VERY explicit instructions for setting the compression on the bellows.

Finally, ten years is the recommended maximum age for these seals. By your description you had a seal that was 18 years old. That's just plain crazy.

To be blunt, you really should read the instructions.

Additionally, you need two sets of new grub screws. One set goes in "normally" and the next set goes in on top of the first set. Sorta double decker style!

[GILow]

Originally Posted by Wotname

Additionally, you need two sets of new grub screws. One set goes in "normally" and the next set goes in on top of the first set. Sorta double decker style!

And then, if you are paranoid about it like me, you add a shaft anode as a backup. [emoji846]

[Wotname]

Originally Posted by GILow

And then, if you are paranoid about it like me, you add a shaft anode as a backup. [emoji846]

You're not Robinson Crusoe

[wyeiwyr]

My PSS had a vent line. I always pumped dish soap down the line before putting her back in the water, then burped it (even tho that is not necessary). My thinking was it would lube the seal at start up. Never had trouble with that seal in the 6 years we had the boat.