Advice on a PSS dripless. Its leaking!

[jack boats]

I have a 2001 420CC with a PSS dripless packless stuffing box. The weekend before last I was out on SD BAY under power. After setting sails and killing the motor I heard water flowing unusually. I went below and saw water pouring through the space between the steel rotor and the graphite flange. That secures the bellows housing to the shaft. I tightened the screws on the hose clamps until the water stopped rushing in, Got the boat to a dock and read my manual which isn't giving me much info. I thought I might have overtightened the clamps so I backed off those until I got water leaking in and then retightened enough to stop it.

Skip to 2 weeks later and I get a call from the marina saying someone noticed my bilge running. I immediately went to the boat and saw that water was again leaking in through the same place. I tried tightening the clamps more but didn't stop it. I then placed a spare clamp around the belows towards the middle and tightened it just enough to force more pressure on the flange and rotor faces which stopped the leak.

So what I'm wondering is, Is this a common part that needs replacing every 8 years or is there something I can do to fix this or maintain it so that I'm safe at least until I get the boat hauled for a bottom paint?

I gotta say I'm really surprised that this is the best system out there. It seems like the whole ship rests on this one piece of rubber doing its job and if it gives out theres no way to stop the leak! hope your bilge pumps are working and get to shallow water, wow!

 

[Rick D]

Hose Clamps?

Jack: the usual reason the shaft seal leaks is that the collar slides up the shaft because: 1. The installer or subsequent mechanic failed to use two sets of piggy-backed set screws, 2. The set screws were re-used, 3. No lock tight was used, 4. the shaft has moved (check your motor mounts), or 5. improper torque was applied.

It is also possible the carbon was scored, but not likely.

In my case, I replaced the bellows at 1000 hours and ten years, per their recommendation upon my asking. The bellows appears perfect and I used it as a back up.

I would recommend you review the manual ( http://www.shaftseal.com/about/installation_instructions/ )
and re-install using new set screws. I would put an appropriately-sized shaft zinc in front of the collar as a back-up. Most certainly, I would take off that clamp you put on the bellows. Best of luck to you. Of course, you may want to call their customer service line tomorrow.

 

[walmsleyc]

It's important to ensure that the stainless rotor on the shaft is secure, and hasn't moved. It sounds like your issue might be that there isn't enough pressure, from the bellows, pushing the graphite bushing onto the stainless rotor on the shaft. As long as nothing else in the your drive train has moved (shaft sliding into the coupling I suppose?), then you should check to see if the rotor has moved. To allow easy checking of this on my PSS, I place a tape mark on the shaft exactly 1" forward of the PSS. If the PSS were ever to slip, I would easily be able to see.

If nothing has moved or shifted, then the system is improperly adjusted or the bellows are losing their elasticity.

Maybe the graphite collar is not properly aligned?

It seems a bit strange that adjusting the clamps that hold the bellows to the graphite collar affects a water leak between the graphite collar and the stainless rotor. Sounds like something is not aligned correctly, or the bellows are no pushing hard enough on the rotor to ensure a seal.

Are the double sets of allen screws in the rotor tight and secure?

Chris

 

[jack boats]

Leaky shaft seal

I thought that the rotor may have shifted creating a looser seal or that the bellows was just not as resillient as original. by tightening the screws on the clamps I think I was just forcing the bellows to elongate and give me enough pressure to stop the leak. I'm hoping my temporary fix will keep me floating until I can fix it properly. speaking of which, is repositioning that rotor something you guys have done? and with what difficulty. I'll probably give this a shot myself this weekend if I can safely reposition the rotor without hauling the boat or being too concerned that by loosening the rotor to reposition will result in a flood of water coming in.

Also if I'm succesfull with repositioning the rotor, do you guys feel like this is a reliable fix or is this something I really should have a pro do?

 

[duality]

per their website they recommend changing the bellows every 6 years, they have a rebuild kit available.

this is from their site;

As with any rubber hose below waterline, the PSS bellows must be inspected on a regular basis for any sign of wear, aging or chemical deterioration. PYI suggests preventative maintenance. The PSS bellow should be replaced in six year intervals. During bellows replacement it is recommended the o-rings & set screws in the stainless steel rotor also be replaced.
Bellows may need to be more frequently inspected in an environment where non-sealed batteries emit sulfuric acid. Sulfuric acid vapor will accelerate rubber deterioration, as will an ozonater.

 

[walmsleyc]

Repositioning the rotor should be fairly easy, but you should have on hand a replacement allen screw set so you don't have to reuse the old ones. There are two "o"-rings inside the rotor that make a water tight seal to the shaft. Personally, if adjusting the rotor aft to solve your problem, I would have a slight concern that the "forward" o-ring might get slightly damaged as it passed over the dimple left by the set screw. Maybe it's not that much of a problem.

Otherwise, you should just mark on the shaft the current position, loosen the set screws, and twist the rotor on the shaft while pushing it forward. I can't remember the exact instructions for adjusting the pressure of the bellows, but something like 1/2-3/4 of an inch should be sufficient.

Chris

 

[Rick D]

Easy to Reposition

As walmsleyc said, it is a quick fix and it should be adequate. Get new set screws though. A hardware store should have them. I doubt they are stainless but that's easy to check. You also need to add some locktite. I would put a zinc on before it when you are done just for added protection. I have repositioned them many a time.

PS: if they now recommend a rebuild kit in eight years, I'd get one and install it your next haul IMHO.

 

[Don12364]

How a PSS can leak

On a different, but similar type, of seal (Deep Sea Seals) I was aground in my berth and went astern violently and at full power to extricate myself. Unknown to me the engine moved so far backwards on its flexible mounts - say 1/2" - that it caused the seal bellows to fully collapse and then the only thing to give was to slide the bellows up the prop shaft. As soon as I engaged forward gear the engine resumed its normal position but left a 1/8" gap between the two faces of the seal.
Motoring single handed for half an hour and the boat felt 'funny'. The first I knew was, when looking down into the cabin, I saw my best sailing shoes come floating towards me. I had no idea where the leak was and, because it was now underwater, it was impossible to see. Result I pumped furiously until I arrived in harbour.

Nonetheless I fitted a PSS to my latest boat because it had a stainless collar to limit the above problem - and I made darned sure that I drilled decent holes in the propshaft to receive the grub screws in the sliding collar.

Am now 15 years older, a good deal wiser and no trouble whatsoever with the PSS.