Advice requested: PSS bellows loose and leaking

[Bigsfish]

I’ve been using dripless seals for years and do the maintenance on them with my haul out and have never had a problem, so my question is how many of us have had a catastrophic problem if you had done the maintenance? Compared to a wet bilge and the constant adjusting of the two nuts that are never easy to get to I much prefer dripless.

[cappy208]

This has been my first PSS seal I’ve owned. Been a charm. Replaced bellows and orings while changing shaft last winter. Replaced because when I bought the boat 3 years ago there was no indication of age. Now I know I have 5 more years until it needs anything.

One other comment rings true. If the dss seal is leaking it is likely from debris, seaweed or other physical junk in between the seal face and the stainless ring. A quick dislodge and flush into the bilge is all it takes to clear it up.

I have found that a rubber bellows will allow much more give with shaft whip than a packing gland. (Thus the new shaft last winter).

[Group9]

Originally Posted by aboatman

Since when is a dripless seal "dangerous"? Thousands of boats are using them including mine.

We had a sportfish sink within sight of our boat a couple of months ago. PSS shaft seal was the culprit. I don't know the age or anything. But, it was sad to see..

We have them on our boat, too. We have hose clamps on the shafts to keep the disc from migrating forward (we learned that trick on our sailboat with a PSS after the disc pulled that trick on us one day).

[dhmeissner]

Here’s a little reading:

https://www.passagemaker.com/technic...ss-shaft-seals

Dripless Shaft Seals – May be Dripless, But Not Maintenance Free

http://www.pyiinc.com/downloads/pss-...structions.pdf

The Promise is having one installed. I’m looking forward to a dry bilge.

[Ski in NC]

I have personally been involved in investigations of a few sinkings and floodings related to dripless seals. On some models the seal housing has a plastic bushing that keeps the shaft centered for the lip type seal to work. If cooling water is not flowing for some reason, the bushing heats up and melts, seizing to the shaft. Then shaft rotation rips the hose from the shaft log. Can be from towing or if the cooling line gets clogged.

Another casualty refers to a cooling water cross-over line which cools both seals even if running one engine. The problem was the boat used water lift mufflers which had the outlet higher than the turbo. So the guy fried a starter and had to come in on one engine. Got to the dock and a week later found the engine was completely full of water and needed an overhaul.

I have not been involved in investigating any PSS boot failures, but have seen many leak at the actual seal interface. Many times no leak dockside or at slow speed, but up at fast cruise, it was spraying. Cost one boat a gennie as it was mounted between the shaft seals and ingested the salt spray. Locally we fab spray deflectors on these if there is any critical equipment nearby. Spray deflectors kind of defeat the purpose!!

So when I built my boat, it was classic bronze packing gland with teflon coated packing. I can handle drips (almost none) but can not handle a large ingress from a ripped seal hose or boot. Not likely to get a gross failure of a bronze packing gland.

Be careful with these type seals!!

[rking]

Have had both PSS and Tide. Replaced current boat with Tide marine System Three years ago, not one drop I know of sense and can replace in water with extra seals already installed on shaft , although I have not had to change the original seals ( twin screw, with two spares on each shaft) yet. PSS was always a constant maintenance trying to stop leaks with Salt water sling. One boat was brand new and the other one used when I purchase them. Much prefer tide system over PSS, although Traditional
Stuffing box with the new packing materials, such as Gore-Tex or Tefpack would be considered.

[sunchaser]

[mahal]

Thanks for your input Ski.

Is your stuffing box water cooled? Is water cooling needed if Gore or similar packing is used. BTW, the cost of a water cooled unit is around $600 vs. $140 for the non water cooled.

[Ski in NC]

Regarding water cooling- I did not install a water tap on my ride, and I cruise 18-23kts when in the fast mode. Packing gland stays cool at that speed. I did make sure I could drill and tap the gland for cooling if it ran hot. But it runs cool.

When I first splashed it, it did get hot. Was getting all ready to drill and tap it, but magically it on a single day started running cool. I guess it was break-in. Took about 5hrs running time I guess. Been cool since and I have adjusted it like twice in the last 1000hrs or so.

If you are an 8kt boat, I can not see the need for cooling water on a standard packing gland.

[mahal]

Thanks Ski. I appreciate the help. Good to know that water cooling can be added to a non water cooled unit just in case.

[Ken E.]

Originally Posted by sunchaser

+1. Mine work fine.

[angus99]

Originally Posted by Ski in NC

Regarding water cooling- I did not install a water tap on my ride, and I cruise 18-23kts when in the fast mode. Packing gland stays cool at that speed. I did make sure I could drill and tap the gland for cooling if it ran hot. But it runs cool.

When I first splashed it, it did get hot. Was getting all ready to drill and tap it, but magically it on a single day started running cool. I guess it was break-in. Took about 5hrs running time I guess. Been cool since and I have adjusted it like twice in the last 1000hrs or so.

If you are an 8kt boat, I can not see the need for cooling water on a standard packing gland.

Ski, is the cooling water always to cool a packing gland? Mine has a cutless bearing just outboard of the pg—tight up against a cavity in the hull—that looks like it wouldn’t get much raw water flow without a water line feeding it. I don’t know if Mahal’s is built the same way or if, in fact, I’m citing the actual purpose of the water line.

[Ski in NC]

"Cooling" tap can also be an advantage as described above if there is a lot of dead volume between the gland and the hull exit. Flushes water that might otherwise become oxygen deprived and thus create corrosion issues with the shaft. Depends on the boat. If a long tube, then I would put in a tap. Short tube, probably no need. Water is moving around in there and will exchange. On mine I have about a 4' FG tube with gland on one end and cutlass on the other. But bottom of tube has a few angle drilled flush ports exposed to water flow underside. So it flushes naturally.

[mattkab]

Didn't mean to start a debate on whether dripless or packing gland is the right choice, but this conversation has been interesting regardless.

I ordered new set screws and o-rings from PYI, and will replace those next weekend, but will do the complete rebuild kit on the next haulout (this spring).

Keep going with this thread, this is informative!

[mahal]

Originally Posted by angus99

Ski, is the cooling water always to cool a packing gland? Mine has a cutless bearing just outboard of the pg—tight up against a cavity in the hull—that looks like it wouldn’t get much raw water flow without a water line feeding it. I don’t know if Mahal’s is built the same way or if, in fact, I’m citing the actual purpose of the water line.

Thanks Angus. I'll look into how mine is set up.

[AusCan]

Originally Posted by Bigsfish

I’ve been using dripless seals for years and do the maintenance on them with my haul out and have never had a problem, so my question is how many of us have had a catastrophic problem if you had done the maintenance? Compared to a wet bilge and the constant adjusting of the two nuts that are never easy to get to I much prefer dripless.

Constant adjusting?
You do maintenance on your dripless seal every haulout. I tightened my packing gland twice in 1000 hours. It was a two minute job each time. No dripping. What's not to like?

Its not that dripless seals are dangerous. Its just that a (rare) catastrophic failure results in lots of water inflow; enough to sink a boat. Properly maintained the chance is almost zero, but equipment is not always properly maintained (even when it has been "serviced")

That potential for a catastrophic failure on a traditional stuffing box is almost zero. At worst, perhaps a loose packing nut could unscrew completely, (extremely doubtful) but it could then be screws back on.

[angus99]

Originally Posted by Ski in NC

"Cooling" tap can also be an advantage as described above if there is a lot of dead volume between the gland and the hull exit. Flushes water that might otherwise become oxygen deprived and thus create corrosion issues with the shaft. Depends on the boat. If a long tube, then I would put in a tap. Short tube, probably no need. Water is moving around in there and will exchange. On mine I have about a 4' FG tube with gland on one end and cutlass on the other. But bottom of tube has a few angle drilled flush ports exposed to water flow underside. So it flushes naturally.

Thanks, Ski. Makes all kinds of sense.

[dhmeissner]

Originally Posted by angus99

Thanks, Ski. Makes all kinds of sense.

That sounds like a similar setup to my boat. My shipwright wants to have water flow to the forward cutlass bearing as well as the PSS.

[Maerin]

Maerin is fitted with a PSS seal, and like many others I was long overdue for bellows replacement. The recommended 6 yr. replacement stretched out to more like 9, and that was from the time I acquired the boat. The PO had NO records, so who knows how long? A new bellows, new O-rings in 2015. I was diligent in facing the surface of the stainless collar, polished it on a platen and lapped the surface with compound.

Subsequent to that service, I was plagued with some irritating leakage. Nothing of consequence, just a few drops that it would sling out while underway. As some point I considered that I may have had the surface TOO polished, so I took a long strip of 600 wet/dry and slid it between the graphite collar and the stainless, grit side to the stainless. I kept it in place while the shaft ran a dozen or so rotations in idle, holding the end of the strip. Flushed it, and hasn't spit a drop since. Just FWIW for those servicing theirs.

And... a +1 regarding water flow. There have been cases of other Selene's that are very low hours/use with shaft crevice corrosion, so there is likely merit in water flow as relates to corrosion rather than strictly cooling.

[Puffin_NT32]

After 13 seasons, 2,000 engine hours, I'll be installing a PSS maintenance kit on my seal before launch next month. Over the years, I've keep exterior of seal clean, wiped a little olive oil or 303 Protectant on bellows, and tightened clamps. Looks brand new. No spray, but I've seen some slight leaks (no more than 1/4 cup) over the last several years. I know that some of the water under the seal is from my hot water tank pressure valve hose carried into the bilge.

PSS rep at boat show says to periodically "burp" the seal, by rocking the carbon stator forward to flush any debris between stator and SS rotor. A "catastrophic failure" is usually a tear or split in the bellows, and I've placed a 4" x 5' roll of Flex Seal rescue tape near the seal in event of a failure. Wrapping the bellows in tape should get you back to port. Hope I never have to use it.