PSS shaft seal

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Siriussl23

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Thought this information may be useful to anyone with a PSS shaft seal.

About 5 weeks ago the I developed a serious leak between the graphite ring and the stainless steel rotor of the seal. Closer inspection revealed that the there was only two of the grub screws that are supposed to lock the rotor in place and these were loose. There should be four in total - two locking down the first set.

This allowed the rotor to back away from the graphite ring which broke the seal. The rotor should compress the bellows of the seal.

I probably should have this on my pre-sail ceck list. I've learned now that it's worth checking that the screws are in place and that the second set of screws are in place to lock them in. Having water coming in is scary.
 
The standard safety device is to put 2 stainless pipe clamps at 180 degrees on the shaft just behind the rotor with a little gap.

Firstly it saves massive failures and secondly it serves as a reference to check for movement. Even if you can only touch it, and not see it, your finger can tell if the gap has disappeared.
 
I'm afraid it's a constant source of leakage - the heating cooling of the shaft causes an inevitable movement.

Mine have a small dimple in the shaft and I use cyanoacrilic Loctite, rather than the twin grubscrews which I've found pretty useless.

Apart from that, and a habit of overheating after about 12 hours running, the PSS has been trouble & leak-free in about 3500 hours of use.

I now check mine as part of my standard servicing, every 100-120 hours.
 
Ours doesn't leak a drop - but it gets a bit warm and squeaks sometimes. I don't count this as a fault. I keep meaning to check the compression of the bellows - I might have been a bit enthusiastic when I fitted it. At the moment, I just press the bellows back and allow a little water through to lubricate it occasionally.
 
A few comments that relate to your post and to some other replies. I fitted a PSS 2 years ago to replace a 'Deep Sea' Seal, the PSS is infinitely better engineered and IMO much more reliable. Being ultra cautious about the possibility of big holes in the boat we had fitted 2 jubilee clips to back up the older DSS and so did the same with the PSS. I would have one of these even with a conventional seal to avoid the shaft vanishing out astern if a coupling failed which it did once on a delivery trip I did on a friends boat.

As to the rare occurence of an overheating problem I think that may now have changed with newer advice from the makers or distributors. There are or were 2 types of PSS, one for normal shaft speeds and one for higher speeds which has a water cooling injection point added and for high shaft speeds sea water is fed to this connection on the PSS from the engine circuit. I was advised by PSS who I contacted by e-mail and Lake Engineering in Poole to fit this type of seal anyway even with a normal shaft speed and to simply take a hose from this to above the waterline because this would 'self-burp' and ensure no entrapped air after a relaunch or drying out. It would also give a small head of water to counter any tendency at high boat speeds for a venturi effect to suck water out from the stern tube. We have had no need to burp our seal ever, nor have we had any sign of overheating and haven't had a drop of water pass the seal.
 
I've also had a Deep Sea seal (on my previous boat) and now have a PSS seal and would echo your comments about the relative quality. My PSS has the injection point but I don't have a 'breather' tube connected to it. I just 'burp' the seal when the boat is re-launched and that's it for the season. So far (4 seasons) it's been faultless.

If I had a bilge keeler or regularly dried out I would want to fit the tube but as it stands it seems to me an unnecessary bit of kit that might fail for whatever reason and leak!
 
You would'nt be the boat that was in trouble mid Solent approx NW of Wotton Creek a month or so back would you? I was in the area and was listening in during the Pan Pan. It would appear that a PSS type seal had failed and although the skipper was getting the situ under control a lot of Solent was coming in through the damaged/displaced seal.

I will stick with my sticky old 1 drip per minute job, ta very much..

Regds Nick
 
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