My dripless shaft is leaking

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larman

Senior Member
Joined
Nov 29, 2017
Messages
228
Location
United States
Vessel Name
Livin The Dream
Vessel Make
Sea Ray
We discovered our dripless shaft is leaking while underway. Looks like it was not installed with enough pressure on the bellows. Is there a way to adjust this while in the water?
 

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I assume this is a PSS? Yes, you remove the little set screws, push it tighter, and then put in new set screws and tighten them down. You can’t reuse the set screws — need to use new ones, and two go in each hole, one on top of the other. It takes some force to push the ring tighter while you tighten the screws, so this is a two person job.

You should first try pulling the bellows back and let some water flow through, it could just be gunk in the seal causing the leak.
 
How old is the seal? I believe that PSS recommends replacing/rebuilding it every 6 years or so. The bellows looses strength I guess.
 
If you do decide to add tension, keep this in mind. There are two o rings inside the stainless rotor. The set screws will upset the metal of the shaft when tightened. If you move the rotor enough to drag the o rings across the screw damaged shaft area you can end up with a leak there.
Usually, when those are installed, you put a mark on the shaft when the bellows is under no pressure, then slide the rotor up a prescribed amount and tighten. I have had them last for 20 years without intervention. (Don’t recommend going that long though)
As mentioned, try flushing some water through it. Many times that will cure the drip.
 
PSS offers a couple of videos

suggest to look at them, BUT, do not assume is the bellows pressure, could also be dirt on the surfaces and even a misalignment on the shaft.

Recently have to do go over because of dripping,I think fixed it except the misalignment on the shaft, but that is another story




"The stainless steel rotor of the PSS Shaft Seal is secured using set screws. It is important to NEVER re-use and ALWAYS double stack the set screws. In this video we'll show you how to properly change out the set screws on a PSS Shaft Seal."
 
On not using the old screws.
If you are lucky, the installer used two sets on each thread, remove them and change the order until you get a new set ordered.
 
Further compressing the bellows may not be the solution. If the rotor and or stator are dirty or worn it will still leak. A mechanic I trust once told me to try toothpaste between the rotor and stator. Toothpaste is a mild abrasive that is water soluble. It will self flush as you run. I've never tried it so can't speak to the effectiveness of the technique.
 
Thanks this is less than a year old, installed by a marine mechanic. Thanks all for the tips and I have watched the video. Looks real easy on a work bench out of the water. We are in Block Island heading back to Long Island. It’s not that bad will keep an eye on it and fix when we are back on the slip with new set screws.
 
It already looks pretty compressed to me, but it's a bit hard to tell from that angle. As Comodave said, they can lose elasticity and then will need to be replaced. Other things noted which cause leaks are dirt on the faces, sometimes it's a simple as pulling the bellows back and flushing it out, or you can sneak in a bit of 600 wet or dry and rotate that around and see if that improves things. If the surfaces are pitted or damaged, it will need to come out and both the stainless ring and carbon stator will need to be surfaced on a glass plate or granite block.
The other think to consider is shaft alignment, if it's off appreciably this can cause leaks, especially if the shaft is not perfectly true or you have a bit of imbalance in the rotating assembly.
These PSS seals can be a bit fussy...
 
Well thought we had it fixed, but it started to spray again after we flushed it out.
 
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Add a back-up to the set screws-either a hose clamp or shaft zinc (or similar in stainless). My set screws failed when I was crossing the straight of Juan de Fuca. My bilge alarm saved me.
 
We discovered our dripless shaft is leaking while underway. Looks like it was not installed with enough pressure on the bellows. Is there a way to adjust this while in the water?
You also need the safety collar, put it in place right tight to the working collar and you can then move working collar it so that the bellows are more tight and yes let some water flow incase there are dirt in the seal surface.
Anything for further info call PYI PYI Inc. | PSS Shaft Seal
 
In my experience, adding compression to the bellows does not resolve the problem. PYI is very specific in the installation instructions about how much the bellows should be compressed. Unless that was not done initially, it should not be further compressed. Check this first, often the installer will make a mark on the shaft with a Sharpie showing how far they were to move the stainless rotor for the proper compression, it may still be there.

More here Keeping Your Bilge Dry with Dripless Stuffing Boxes | Steve D'Antonio Marine Consulting
 
Sorry that I cannot resist this one.. PSS "the solution to a problem that never existed". and an expensive gadget to add a means of sinking your boat in minutes. And a boon to yard service managers.. replace the boots every 6 years or when your boat sinks from a leak, the insurance company will reject your claim.
I am going to replace my two PSS "dripless" gadgets with old fashioned Goretex
stuffing boxes next time around. I will sleep better.
 
See the attached file. Beware, this can happen when the seals are aging!
 

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I am going to replace my two PSS "dripless" gadgets with old fashioned Goretex
stuffing boxes next time around. I will sleep better.
That's what I have and no way I'm changing them. They don't drip if adjusted properly, and I have pans under them in case they do.
 
Not to mention that if they do leak it will be drips and not a flood.
 
How old is the seal? I believe that PSS recommends replacing/rebuilding it every 6 years or so. The bellows looses strength I guess.
If lightly damaged/leaking, the carbon fiber tube (stationary) and stainless tensioning ring (spinning) can be pulled in drydock and faces polished with 600 -1500 grit wet sand paper on a piece of window glass.
Buying just the bellows is a lot less expensive.

I’ve done it twice with good success.

I did bridge the water feed/cooling lines so both sides are cooled when operating on one engine (Twin engines).
 
Sorry that I cannot resist this one.. PSS "the solution to a problem that never existed". and an expensive gadget to add a means of sinking your boat in minutes. And a boon to yard service managers.. replace the boots every 6 years or when your boat sinks from a leak, the insurance company will reject your claim.
I am going to replace my two PSS "dripless" gadgets with old fashioned Goretex
stuffing boxes next time around. I will sleep better.
I've taken that approach on some projects, installing a sump with a dedicated pump under the stuffing box, to achieve the desired dry bilge.
 
[QUOTE="adornato, post: 1236343, member: I am going to replace my two PSS "dripless" gadgets with old fashioned Goretex
stuffing boxes next time around. I will sleep better.
[/QUOTE]

I have never understood the logic of using unfiltered raw water to cool and lubricate a shaft seal. Too much can go wrong, set screws, (stacked no less) bellows compression, alignment, water flow and it’s contents.

Provided the finish on the shaft is right, we have figured out long ago that a lip seal, bathed in oil is pretty reliable, just like your crankshaft.

Norscot has been making this type of shaft seal for over 30 years, mine are now 28 years old. I’ve replaced the lips seals twice at a material cost of about $40 for two, 3” shafts.
Neither leak a drop and if the port shaft starts again it will be one drop of ATF a day.
 
A couple of responses have mentioned shaft alignment. If the shafts thru the tunnel are not evenly centered, it’s probable that the shafts are not aligned correctly. This alignment angle results in the bellows/graphite seal having uneven pressure around the ring causing leaks/spraying particularly at higher speeds.

My bellows were way past their use by date, and needed replacement. A shaft shop changed them and resurfaced the seal and ring faces. Thereafter I had a couple of years of leaking “hell”, lifting the boat several times, adjusting the rings with more and more pressure, replacing bellows, fitting slightly oversized graphite seals, until a smart young shipwright identified an angle issue caused by an incorrect shaft alignment.

After inserting 5/16” spacers under the 4 engine mounts (raising the height of each engine) the leaking issue was eliminated. Pic attached after the engine height was adjusted.

I trust this assists others. Cheers
 

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[QUOTE="adornato, post: 1236343, member: I am going to replace my two PSS "dripless" gadgets with old fashioned Goretex
stuffing boxes next time around. I will sleep better.

I have never understood the logic of using unfiltered raw water to cool and lubricate a shaft seal. Too much can go wrong, set screws, (stacked no less) bellows compression, alignment, water flow and it’s contents.

Provided the finish on the shaft is right, we have figured out long ago that a lip seal, bathed in oil is pretty reliable, just like your crankshaft.

Norscot has been making this type of shaft seal for over 30 years, mine are now 28 years old. I’ve replaced the lips seals twice at a material cost of about $40 for two, 3” shafts.
Neither leak a drop and if the port shaft starts again it will be one drop of ATF a day.
[/QUOTE]



I have Norscot shaft logs on our current boat. I really like them too.
 
If you get to the point of replacing them, go with Tides lip seals. I had PSS on my current boat and they were both “painting that black line” of carbon in the spray path of the water. I messed with it. Increased bellow pressure. Still leaking. Boat was out for other service so I said, EFF it….replace them. Tides….never an issue again.
 
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