PSS Shaft Seal

S

SteveIOW

Well-Known Member
Joined
3 Oct 2008
Messages
157
Location
Isle of Wight
Visit site
I'm in the process of the replacing my old, worn, Deep Sea Seal with a PSS Seal. The prop shaft is 1.0 inches diameter and the stern tube spigot 1.5 inches outside diameter. The PSS seal ordered and supplied is designed for these two dimensions.
The first problem was getting the rotor to slide down the shaft. The ID of the rotor is 1.003" and the OD of my 1.0" shaft actually measures as 1.003". The rotor was tight on the shaft even without the two O rings fitted in the rotor. Anyway after hours of rubbing away at the shaft with emery cloth the rotor is now on the shaft complete with O rings so that problem's solved (eventually).

The PSS bellows are secured to the stern tube with two jubilee clips. The installation instructions say to secure the bellows such that the graphite flange is concentric with the shaft. The ID of the graphite flange is about 4 mm larger than the shaft. However the graphite flange is about 5 inches away from the jubilee clips so the bellows just sag and the graphite flange rests on the top of the shaft. Has anyone else found this? Solution??

I thought the nitrile bellows were one piece but it turns out the aft end has a nitrile insert tube to bring the ID down to 1.5" to match my stern tube. The instructions only show one item number for the bellows. Should the inset tube have been bonded into the bellows. If so the bonding has failed on mine. Am tempted to use a little super glue but should not need to on a new item. Suggestions please.
 
Last edited:
SteveIOW said:
The prop shaft is 1.0 inches diameter and the stern tube spigot 1.5 inches outside diameter. The PSS seal ordered and supplied is designed for these two dimensions.
........

I thought the nitrile bellows were one piece but it turns out the aft end has a nitrile insert tube to bring the ID down to 1.25" to match my stern tube.
Click to expand...

I'm confused.:confused:
 
Sorry to confuse. The stern tube spigot is 1.5" OD and the nitrile insert in the bellows "brings the ID down to 1.5" to match my stern tube". Don't know why I typed 1.25". - Must be my age. Will try to correct my original post.
 
Sounds fishy. Why would an American company need to fanny about with spacers for a 1.5in dia sterntube? There is no mention in the fitting instructions or component list.
One forum member had two problem units sold to him as PSS and there was some suggestion that they were counterfeit. I recall that one odd thing was that they were supplied with some sort of spacer.
I should waste no more time and get on to your supplier and photograph the thing as well, as a record.
 
I have vague memories of my (genuine) PSS shaft sea bellows having the insert collar.

Don't worry about it.

Regarding square to the shaft, just lift the graphic based ring until it's concentric and check its square. Alternatively lift until it's square and then check its concentric. It's not that critical either way, but I've only ever fitted two so no vast numbers to go on. Neither have leaked though and the second one is still going strong after 11 years.
 
KREW2 said:
Is the PSS shaft seal that much better than a Radice seal to justify the vast difference in price?
Click to expand...

No (in my opinion - for what it is worth). They work on different principles and the PSS is much more complex in both concept and execution, but there are many applications where a Volvo/Radice type will not fit.

Personally I like the simplicity of a one piece moulding with lip seals as to my mind it is both more robust and not prone to failure, although the lips may eventually wear and leak.
 
I don't quite understand the 'drooping graphite' part. Once the stainless steel collar is moved aft to compress the bellows the graphite will self-centre.

The rubber insert is a standard arrangement, although it doesn't seem to be listed. No need to glue it, the hose clips will hold both it and the bellows perfectly well.

The difference between the PSS and the Radice, for practical purposes, is that whereas the Radice seals against the shaft the PSS seals against itself. If the shaft is marked, damaged or, as in the OP's case, he has needed to abrade it, the Radice may not seal perfectly and in the worst case might be destroyed quickly be wearing against shaft scratches, nicks, etc. The PSS will seal on a worn or damaged shaft provided the O-rings will slide along without being cut.
 
SteveIOW: a tip: once the bellows are compressed and clamped, fit a hose clip around the shaft so the bellows cannot expand if at some future time you forget to retighten the bellows hose clips. Please don't ask how I know this to be prudent ;)
 
Any spacer is one more thing to go wrong, there is no reason for one, it is not described in any of the specifications. The manufacturer supplies your exact size.

I would fire it back for a refund even if it meant fitting some other inconvenient alternative
 
Fitted mine over winter. I endorse all of vyv's comments. Yes the 'graphite part' will droop by its weight but becomes square on when the SS collar is pushed against it. Mine had an insert but the jubilee clips will compress both bellows and insert to make the seal, no need for super glue!
I fitted mine due to 'crevice corrosion' under the lip seal.
I also use a jubilee clip as belt and braces and another one a few millimetres back from that so I can see if there has been any movement.
Remember to check that the seals faces turn easily by hand if the boat has not been used for some time ( in case the faces have become gummed together a bit)
 
doug748 said:
Any spacer is one more thing to go wrong, there is no reason for one, it is not described in any of the specifications. The manufacturer supplies your exact size.

I would fire it back for a refund even if it meant fitting some other inconvenient alternative
Click to expand...

To get a refund you would have to persuade them that it's not fit for purpose.

Just because you have a dislike of the design is almost irrelevant.

As I and several others have said, the PSS works very well and is more or less maintenance free.

Other shaft seals available but I can only speak as I find.
 
doug748 said:
I have had a PSS seal for fifteen years, I think it would be worth re-reading my posts.
Click to expand...

And we've had PSS seals on our boats for a similar period.

I didn't understand your outright condemnation of the collar that they add to fit odd sized stern tubes.

I seem to recall we've got a collar on our present version of the PSS seal on Serendipity. Its been on for 11 years and had never given us any trouble. (Actually that's a lie, it took to squeaking at certain shaft revolution speeds for a while as there's very little water that gets up our stern tube.)

I note others have admitted theirs have come with a collar as well. I suppose that its the way PSS make sure that they can supply a variety of rubber bellows to fit a variety of stern tube sizes without having dozens of different rubber bellows sizes.
 
There is as much tub thumping on stern seals as anchors or boat types but they all have their plus and minus points.

I don't want to repeat stuff to the point of boring everyone but given that 1" - 1 1/2" is one of the most common sizes and the manufacturers make an exact match, that is what I think the OP should have been supplied with.
 
doug748 said:
There is as much tub thumping on stern seals as anchors or boat types but they all have their plus and minus points.

I don't want to repeat stuff to the point of boring everyone but given that 1" - 1 1/2" is one of the most common sizes and the manufacturers make an exact match, that is what I think the OP should have been supplied with.
Click to expand...

Thats an interesting comment "that 1 1/2" 38mm is the most common size of stern tube"

Looking at PBO's guide to dripless seals

http://www.pbo.co.uk/gear/dripless-shaft-seals-pbo-buyers-guide-17357

Shows that only 2 suppliers will supply for 38mm stern tube that is Tides marine and PSS.

Now using a spacer is to allow for more sizes of stern tube to be cater for without having very complicated tooling to mold the bellows and as others have said and from my engineering point of view not a problem.

The forum member who had a problem with 2 PSS seals. I determined from his pics and a spare I had on my desk the PSS seal was fitted incorrectly as it happened that his stern tube O/D was the same as the carbon spigot diameter and the clamping clamps fitted so the clamps cut into the rubber as the clamps were fitted over the end of the stern tube so IMHO it was a fitting problem and not a product problem hence the apparent non response from the suppliers.

Yes this could become like an anchor discussion if you wish.

My PSS seal fitted for coming up to 7 years now with out a problem.
 
Would just endorse the point about checking the graphite ring has not "stuck" to the stainless ring if you leave the boat for a while. For me it is quick job to check they are free when setting up the boat. Other than this maintenance free and no drips.
 
Another Hint not in the instructions

If you have to re align the Engine/shaft ALWAYS recheck the seal is still correct

On our project boat we found the alignment was way out so we sorted this out but we subsequently discovered that around 2200 RPM or more the water gusted in because the 2 surfaces were no longer close enough together
 
You must log in or register to reply here.

Share this page

Top