PSS Shaft Seal problems

[Robin]

Is it fed with pumped water or does it just have a tube as an air bleed ( which will have water visible in it) taken above the waterline? If the airbleed type it will not get filled with antifreeze mix. Anyway, IMO there is nothing in the PSS by way of hose materials or 'O' rings that are any different from anything you might find on a freshwater + antifreeze cooled engine?

 

[Simondjuk]

There's a list of chemicals which PSS seals don't like on their website somewhere.

Incidentally, pumping anti-freeze into the sea, whether it be via the exhaust, the PSS seal or both, isn't a great idea. It's rather toxic to marine life.

 

[vyv_cox]

If your name is anything to go by you have a yacht with a relatively small auxiliary engine. As Robin has said it is only necessary to have a pressurised supply to a PSS if you have a powerful mobo capable of high speeds. Those of us with boats used to more modest speeds need only have a tube from the seal to above the water line so that air does not remain in the seal after drying out, i.e. no need for burping.

 

[charles_reed]

the only leakage problems I've had with my PSS seal have been the aftermath of a prop-wrap pulling the shaft out and moving the rotor up the shaft.

Fitting a jubilee clip is a help, but not an answer.

Adjusting the seal, in the water, can be performed with impunity, providing you have the shaft held and reasonable access to the seal. All too often the latter is not attainable.

As to the suggestion that one replaces the PSS with a Volvo seal, could only be made by a highly prejudiced user of the Volvo seal. Having had both, I can assure people that the seals are little different, the Volvo one just costs more and one lives in constant apprehension that the Volvo "deliberate design mistake" will make itself apparent.

 

[Tranona]

the Volvo one just costs more and one lives in constant apprehension that the Volvo "deliberate design mistake" will make itself apparent.

Not sure this is true on the cost front - rather the opposite.

Can you expand on the "deliberate design mistake"?

 

[contessaman]

If your name is anything to go by you have a yacht with a relatively small auxiliary engine. As Robin has said it is only necessary to have a pressurised supply to a PSS if you have a powerful mobo capable of high speeds. Those of us with boats used to more modest speeds need only have a tube from the seal to above the water line so that air does not remain in the seal after drying out, i.e. no need for burping.

hiya,

no sadly no longer in possetion of namesake - its a motor sailer with quite a powerfull perkins. this keeps catching me out. I need to change my user i.d. to used to have a contessa now have a motorsailer man.

looks like it does take a pressure feed from the jabsco pump.

in answer to somebody else's comment I wouldn't dream of blowing the antifreeze out into the sea while winterising, it is possible to rig a poly container under the exhaust to catch the mixture and then feed it back in.

looks like the general consensus is the antifreeze is bad for the PSS.
so what if I blank of that hose while running engine for winterisation? presumably if im not running the engine in gear the shaft will be barely turning and it will not need this pressurised water feed?

 

[Simondjuk]

When you take the hose off, as well as blanking off the tee from the water pump, remember to also make sure the end of the pipe to the seal is secured above the waterline. Running without the pressurised feed is fine. It's only there to make sure the seal stays wet when high boat speeds could otherwise lead to the vacuum created at the aft end of the stern tube sucking the water out of the seal. When stationary or at low speeds the seal will stay full of water from the bottom up without the need to feed any in.

I'm sure you wouldn't chuck anti-freeze out intentionally (although I have seen people do it) but was concerned about the possibility of it happening accidentally and invisibly via the stern tube if the raw water connection to the shaft seal were left in place while the solution is run through (which you've decided against doing now, so it's not an issue anyway).

 

[charles_reed]

Well make sure that you put it in with locktite

Beware the grub-screws are NOT a metric thread or sized socket.

I got my bellows, O-rings and grub-screws direct from PSS in the US, and they provided the correct Allen Key.

Conversely I've always found Aquafax most helpful and reasonably priced (for UK marine suppliers)

 

[charles_reed]

Not sure this is true on the cost front - rather the opposite.

Can you expand on the "deliberate design mistake"?

Cost - I buy in the country of origin, my PSS seal cost $85 in 2002.

The Volvo seal is a paradigm shift away from that price.

The Volvo "deliberate design mistake" only partly in joke as my experience (thankfully not large) is that nearly all Volvo designs have a simple design contra-indication, mainly to do with dissimilar-metal electrocouples. One only has to look at their saildrive designs to see that.

 

[vyv_cox]

Beware the grub-screws are NOT a metric thread or sized socket.

Along with many of the grub screws on the connectors for inch tubing, of which I have many on hood frame, bimini, solar panel arch. I now carry sets of both metric and imperial Allen keys, as using the wrong one invariably rounds the hexagon.

 

[rotrax]

Cost - I buy in the country of origin, my PSS seal cost $85 in 2002.

The Volvo seal is a paradigm shift away from that price.

The Volvo "deliberate design mistake" only partly in joke as my experience (thankfully not large) is that nearly all Volvo designs have a simple design contra-indication, mainly to do with dissimilar-metal electrocouples. One only has to look at their saildrive designs to see that.

I wonder if you could expand on the Volvo saildrive design-is it different to other saildrive designs in the respect that concerns you?

 

[maxi]

Ignore 30boat's advice at all costs. Whilst the PSS seal will cope very well with vibrational forces, the Volvo Seal has, by it's own literature, very little tolerance to vibration or movement of the shaft.

Probably the solution lies in the compresssion of the bellows but, there could be some mechanical damage to the sealing faces, perhaps by some piece of hard debris getting into the sealing gap and creating scoring, or is there any chance that the seal has been subjected to contamination by oils etc.?

 

[charles_reed]

If your name is anything to go by you have a yacht with a relatively small auxiliary engine. As Robin has said it is only necessary to have a pressurised supply to a PSS if you have a powerful mobo capable of high speeds. Those of us with boats used to more modest speeds need only have a tube from the seal to above the water line so that air does not remain in the seal after drying out, i.e. no need for burping.

PSS no longer supply seals without a feed into the carbon block.

Sometimes this has positive pressure for high-speed running, but more usually it is merely to act as an air-bleed to avoid having to "burp" the seal.

 

[Tranona]

Cost - I buy in the country of origin, my PSS seal cost $85 in 2002.

The Volvo seal is a paradigm shift away from that price.

The Volvo "deliberate design mistake" only partly in joke as my experience (thankfully not large) is that nearly all Volvo designs have a simple design contra-indication, mainly to do with dissimilar-metal electrocouples. One only has to look at their saildrive designs to see that.

Guess just shows how removed you are from the real world. The Volvo seal is about half the price of the other major lip seal on the market (Tides Marine). Apart from the purpose (to keep water out of the boat) neither of these have any design feature in common with the PSS seal you compare with. It works on different design principles - and is also substantially more expensive than the Volvo seal.

There are no dissimilar metals in a Volvo seal as it is all rubber apart from the stainless steel clamp to hold it on to the stern tube.

Perhaps if you got your facts right you would not need to try and make a joke (even partly)!

 

[charles_reed]

Guess just shows how removed you are from the real world. The Volvo seal is about half the price of the other major lip seal on the market (Tides Marine). Apart from the purpose (to keep water out of the boat) neither of these have any design feature in common with the PSS seal you compare with. It works on different design principles - and is also substantially more expensive than the Volvo seal.

There are no dissimilar metals in a Volvo seal as it is all rubber apart from the stainless steel clamp to hold it on to the stern tube.

Perhaps if you got your facts right you would not need to try and make a joke (even partly)!

I'm sorry to have misled you, I did not refer to the Volvo seal as having dissimilar metals in it.
Perhaps it would be a good idea to re-read my post and clear up your confusion.

PS I did say similar principles - but I'd agree that hair-splitting could lead your re-action.

 

[Tranona]

I'm sorry to have misled you, I did not refer to the Volvo seal as having dissimilar metals in it.
Perhaps it would be a good idea to re-read my post and clear up your confusion.

PS I did say similar principles - but I'd agree that hair-splitting could lead your re-action.

No, you did not say that it had dissimilar metals. I asked you to expand on the "deliberate design mistake" on Volvo seals and you replied with a load of rubbish about saildrives and dissimilar metals, which is completely irrelevant.

It is clear from what you say that you do not seem to know a lot about the subject as you seem unable to see the difference in different designs (which is much more than "hair splitting") and your information about relative prices of products is way out of date.

 

[Old Troll]

Old Troll

A PSS shaft seal cost Ye Old Troll the sum of £193 50 in Jan 2010. So far it has worked well.

 

[ismith]

Please be aware that one should always use new set screws (grub screws) on the shaft whenever they are loosened and re-tightened. The cupped end is designed to compress onto the shaft one time, and should be replaced with a new set screw after adjusting the compression in the bellows. Please also note that there are two set screws in each hole, for a total of four set screws per unit. Two compress onto the shaft, and two follow those to lock them in place.

Another thing to try is cleaning up the sealing faces with 600 grit wet/dry sand paper. Fold the sand paper in half so the abrasive side is exposed on both sides of the paper. Place the paper between the stainless steel rotor and the carbon graphite flange. Work the paper around the sealing face about twenty times. This will remove any foreign bodies or debris that could be between the faces. Thanks.

Ian Smith
PYI Inc.

 

[Squeaky]

2nd damaged PSS seal

Good afternoon:

I found this old thread and have decided to resurrect it as it deals with my problem - PSS shaft seals.

I re-engined my boat in Aug 2010 and after some research elected to use the PSS seal to replace my old fashioned packing gland however two months later with less than 20 hours on the engine the PSS seal failed which involved a quick lift and replacement. The part of the bellows which fits over the round block against which the rotor rotates was split and it appeared as the jubilee clip had "scissored" it against the edge/end of block around which the clip was tightened. After some discussion the supplier/installed replaced it with a new one which I installed myself assisted by a friend. The replacement did not cost anything but the lift and launch certainly did.

On 9 Aug 2012 while watching the Olympics on TV with my feet up on the salon table I noticed a small amount of water on the shower grate which I decided that my over enthusiastic deck washing friend had sprayed in through the dorade vent and went back to watching TV. After a few minutes I decided to wipe up the water and stood up only to discover the floor boards were afloat.

Panic set in and I tried the electric bilge pump which ran but did not throw out any water so I used the manual bilge pump until the floor board were no longer afloat when I investigated the electric pump and discovered that a join in the pipes had separated. Once this was re-joined the pump made short work of clearing the bilge. One of my first worries was that I might be pumping oily water into the marina however fortunately there was only a slight amount of oil which was soon dispersed with a few drop of dish washing liquid.

Once the bilge was empty I began checking for a leak and discovered water running from aft - from under the drip tray so after a few more Olympic events I got up the courage to empty the starboard locker to check the shaft seal which I decided could be the only source for the water.

A quick check indicated that the seal had failed in exactly the same manner as the previous seal - see photos below.

I can confirm that local TV is total **** during the night as I sat up, watched TV and pumped the bilge every 20-30 minutes until the marina staff arrived at 0900 hrs when my yacht was lifted and held in slings while I rushed around to the marina workshops trying to locate a new seal.

The Volvo workshop had a seal on hand that would fit and as I was in no position to argue or debate the matter asked him to install it quickly before the marina charged me full price for the lift..

I only used the Volvo seal under duress because of my previous experience with a Volvo 2B engine but as the seal is black, not green, I might get used to it and forget that it is supplied by Volvo.

Needless to say I will NEVER touch another PSS shaft seal because, if for no other reason, when they fail they fail big time.

The first photo indicates a knick/hole in material which would have been under the forward edge of the clip - why? It could have been damaged by what I describe as "scissoring" action against the underlying block of material as the clip seemed to have been half on and half off the aft end/edge of this material - see photo four.

The second photo shows how long and jagged the split was.

The third photo shows the length of the material against which the clip is supposed to be clamped - why is the piece so short - there is no obvious reason why it could not have been made long enough to protrude back under the forward end of the bellows giving the aft clip some real meat against which it can be clamped. Is the material so expensive they tried to save cost in making this piece??? I doubt it.

The fourth photos shows the aft end of the piece to which the bellows are clamped. Those are pretty strange marking, in my opinion, for a professionally manufactured piece. Why the curved hollowed out grooves?

The last photo shows the maker name.

All in all, not a happy experience in addition to being an expensive test of the PPS shaft seal.

Cheers

Squeaky

 

[doug748]

A disturbing tale, have you got in touch with the manufacturers?