PSS Seal - How Do I Correct This?

[markpj23]

One of the few (yay) items noted on our survey was the shaft seals showing some corrosion / salt / verdigris on them. Of course they're a bit hard to reach but .....


Is this just a simple wipe-it-down and keep an eye on it item, or is something more advisable? I note that there is no sign of a drip or active leak, just the carbon dust stripe below the shaft.


So what's the best way to clean this up? Forgive the picture - it's the best I could extract from a pdf...

 

[AnsleyS]

The surface corrosion is not a problem but...


The PSS company suggests replacing the bellows every six years and let me tell you (from experience) that a ripped bellows lets in a LOT of water FAST.


If this is a new to you boat, I would pull the shaft back and replace the whole thing. It will be one of those things that you will feel good about doing.

 

[Hippocampus]

The surface corrosion is not a problem but...


The PSS company suggests replacing the bellows every six years and let me tell you (from experience) that a ripped bellows lets in a LOT of water FAST.


If this is a new to you boat, I would pull the shaft back and replace the whole thing. It will be one of those things that you will feel good about doing.

+1. It’s on the list to be totally anal about as you could lose the boat. Also put on a retaining ring.

 

[markpj23]

+1. It’s on the list to be totally anal about as you could lose the boat. Also put on a retaining ring.

By retaining ring I assume you mean something other than the hose clamp around the shaft inboard of the SS collar? If not a clamp then a shaft zinc perhaps?

 

[DDW]

One thing that often is missed on the PSS type seal: if the boat is left for more than a few weeks without the shaft turning, the carbon surface can stick to the stainless surface. When you first start the shaft, it torques the bellows before breaking free. You can see this turning it by hand. That is why they used to say (maybe still do) that you should break this stiction by hand prior to putting the transmission in gear, if the boat has been sitting awhile. This is a pain if the access isn't good, though it can even be done with a stick from a distance.

 

[firehoser75]

Mark,
As has been stated by a couple of other posters, I STRONGLY ADVISE you to conduct a "full maintenance" of your dripless seals. PSS states that the unit should be serviced every 6 years for the standard bellows, and every 10 years for the "upgraded" bellows. For the slight extra cost, I recommend the 10 year unit.

The rubber (like) bellows maintains a spring like pressure that forces the carbon rotor and the SS disc together (keeping the seal intact). The only thing keeping the bellows under compression is the 2 grub screws that are used to hold the SS disc in place on the prop shaft. PSS sells a "retaining collar" that is added as an extra precaution forward of the SS disc to "hold it" in place should the grub screws loosen their grip on the shaft. Cheap insurance in my opinion!! but I guess you could rely on a good quality hose clamp instead. Personally, I would go for the PSS part that is designed for that purpose.
When I bought my boat, the surveyor stated that he recommended replacing the PSS seal as he did not know it's age. It looked in far better condition that your photos show. My insurance company REQUIRED that I replace it as a condition of insurance. I am not an insurance expert, (Pau Hana is), but I suggest don't risk possible issues with your insurer should you need to make a claim, to say nothing about risking your boat and maybe even your lives if you ignore this basically "routine" maintenance?
Good luck.

 

[RickyD]

The surface corrosion is not a problem but...


The PSS company suggests replacing the bellows every six years and let me tell you (from experience) that a ripped bellows lets in a LOT of water FAST.


If this is a new to you boat, I would pull the shaft back and replace the whole thing. It will be one of those things that you will feel good about doing.

I'm a plus one on this response. I see the beginnings of the dreaded "black line" under the seal showing that it is beginning to leak and shed carbon. I just had to replace mine for the same reason.

 

[Hippocampus]

They sell a add on for short money. Two pieces that bolt together around the shaft proximal toward the transmission. It prevents the shaft from falling out. It not part of the pss device. It’s balanced and has no effect on the shaft alignment or balance.

 

[DonW28]

The surface corrosion is not a problem but...


The PSS company suggests replacing the bellows every six years and let me tell you (from experience) that a ripped bellows lets in a LOT of water FAST.


If this is a new to you boat, I would pull the shaft back and replace the whole thing. It will be one of those things that you will feel good about doing.

Having just went through the costly experience of having to change ours out over the holidays in Key West a new one is cheap insurance. It sure would have been easier and much cheaper to have changed it last June when the boat was on the hard for bottom paint. Hindsight right? If I was a long term boat owner I'd probably change the entire assembly every 5-6 years. Not that expensive to keep from sinking.



Don

 

[jimdavi]

You should be fine to wipe salt and Re-check. You can also clean the mating surface. I think PYI has some YT videos on this.

 

[markpj23]

You should be fine to wipe salt and Re-check. You can also clean the mating surface. I think PYI has some YT videos on this.

Thanks Jim. I did see the video on cleaning the carbon seal surface.


I assume the salt buildup is from the mist that they say may be present at speed. Won't kill me to get an evaluation from a mechanic who knows these things.



Planning to haulout next year for bottom paint and I'll do the maintenance kit then.

 

[RT Firefly]

Greetings,
For the life of me, I have no idea why a simple, traditional stuffing box which took little to no maintenance was ever replaced with a device that seems to cause so many problems and has the real potential, with possibly no warning, to sink your boat if it ever fails.



New and improved? Hmmm....

 

[jimdavi]

Yes, I get a very small amount of salt crust, but zero water. Do you know how old the seal is?

 

[markpj23]

Yes, I get a very small amount of salt crust, but zero water. Do you know how old the seal is?

I believe 4 years but need to verify with PO.

 

[Flatswing]

I replaced mine 3 yrs ago - still get a slight salt mist & crusting - slightly less than your pics, not much speed from my old bus.

 

[Bmarler]

it's completely normal to get a little salty buildup on those pss seals. i use my little spray bottle of water that i keep at the bbq grill and give it a few squirts. all that just runs off.
i love pss seals, i get great performance and service life from them. i've never had one slip, but a two piece stainless shaft collar is pretty cheap insurance if you're worried about it.

 

[bglad]

I suggest a spray shield over the rotating collar. Even when they don't leak, they seem to put out a little corrosive mist. Spray shield keeps it from drifting around onto metal and wood around them. Not unusual to find them with a 360 degree ring a fair distance away...

 

[C lectric]

I have dealt with seals like this in my work and they are not dry. They do reduce leakage a lot but not entirely. That crustiness is salt carried by seawater entering past the seal. THe amount is very tiny so the water dries away fairly quickly but it is still present and that fine spray can travel which can cause rusting of steel components nearby that it lands on. Salt will literally absorb moisture from high humidity air.

Rig a cover with an old fender cut to suit with a split down the length facing down. Leave a small gap in that split so collected water will drop out. Use a worm gear clamp to lightly secure the cover over the interface between the stationary ceramic and the rotating carbon part. That way the water spray will be caught on the fender inside, collect and drop in to the bilge and not spray around.
Of course old hoses can also be modified for the same effect. I just had a fender which had no other use for me, was ugly, and was easily cut & trimmed for the purpose.

The worm gear clamp takes 30 seconds to remove for any adjustments needed. I made a holder for the nut driver to be easily accessible so no digging through tool boxes.

Of course for the PSS seal this does not eliminate the need for maintenance. But it will reduce mtce. for other equipment nearby.

 

[dannc]

...
The rubber (like) bellows maintains a spring like pressure that forces the carbon rotor and the SS disc together (keeping the seal intact). The only thing keeping the bellows under compression is the 2 grub screws that are used to hold the SS disc in place on the prop shaft.....

I don't have a boat. We rent. The boats we rents do not use a PSS.

Having said, that I have read quite a bit about PSS, and from the deep recesses of my memory banks, I remember that the set screws were to be used only once and needed to be replaced if the old ones were removed.

Some one who actually has a PSS can fact check me on this one.

I did find the replacement set screws, https://store.pyiinc.com/products/pss-set-screw-kit.

Later,
Dan

 

[captmikem]

A bit of vinegar and an old toothbrush will clean up the outside, occasionally I will take a piece of 400 sandpaper and slip it in between the seal while it is turning to polish up the surface.

M

 

[Southern Boater]

Greetings,
For the life of me, I have no idea why a simple, traditional stuffing box which took little to no maintenance was ever replaced with a device that seems to cause so many problems and has the real potential, with possibly no warning, to sink your boat if it ever fails.



New and improved? Hmmm....

I wonder the same thing RTF, hardly seems big progress.
Reading how others are covering their seals with an external device to prevent misting in the engine room, that’s what I do with our gland packing seals.

 

[Steve DAntonio]

From the photos the seal's stator and rotor do not look concentric. This is a common problem when the shaft is not parallel with and centered in the shaft log. If that's the case, the two seal faces will not be parallel and they will leak. You can try adjusting the position of the bellows (or when you change it, as others have noted it has a 6 year interval) to improve concentricity, but I have rarely had success with this. A Tides lip seal does not have this issue as it is self-centering. More on the subject here https://stevedmarineconsulting.com/keeping-your-bilge-dry-with-dripless-stuffing-boxes/

Set screws, which should be double stacked, and are cupped, should only be used once, that is detailed on the PSS website. Dannc you are correct.

 

[rgano]

I have run dripless packings for many trouble-free years including Lasdrops and PYIs and now Tides. NEVER had any crust buildup like you have nor misting issues either. Something is misaligned. It's not old enough to need bellows replacement, but I wonder about the carbon face.

 

[Frank60]

From the photos the seal's stator and rotor do not look concentric. This is a common problem when the shaft is not parallel with and centered in the shaft log. If that's the case, the two seal faces will not be parallel and they will leak. You can try adjusting the position of the bellows (or when you change it, as others have noted it has a 6 year interval) to improve concentricity, but I have rarely had success with this. A Tides lip seal does not have this issue as it is self-centering. More on the subject here https://stevedmarineconsulting.com/keeping-your-bilge-dry-with-dripless-stuffing-boxes/

Set screws, which should be double stacked, and are cupped, should only be used once, that is detailed on the PSS website. Dannc you are correct.

My shafts are off center and was having trouble with proper seals. Investigated Tides, but Tides recommends that your shaft be within 1/8 inch of center to use their lip seal. After consulting with PYI, I switched instead to oversize carbons and the PSS Pro bellows. This solved the problem for me. If you're going to install new seals, spend a little more for the Pro seals and get the oversize carbons if you have an off center issue.

 

[markpj23]

Thanks for all the replies. Will be investigating this further once aboard - hopefully next week!

 

[steved59]

I had my PSS seal changed a couple of years ago, fitted by a reputable marine engineering company, since the change I've had a continual black carbon 'ring' completely around the the surrounding area. Is it possible that the bellow can be compressed too much, and therefore have too much pressure between the collar and carbon bit?

Thanks