PSS prop shaft seal

[uxb]

I've bought one..

I wish I'd read into them a lot more before it arrived- otherwise I'd never have ordered it.

They get good write ups. Plenty people have fitted them. It looks well made.

But the thought of all that's between my boat and the bottom is a bit of carbon being pushed onto a stainless steel plate will keep me awake at night worrying.

Logically a bit of rubber against the shaft is the same but somehow I think it'd sleep better with that.....

What to do?

 

[Tranona]

While you are right, there are more secure designs around the PSS has a good reputation if it is set up and operated according to the instructions.

 

[davidej]

I've bought one..

I wish I'd read into them a lot more before it arrived- otherwise I'd never have ordered it.

They get good write ups. Plenty people have fitted them. It looks well made.

But the thought of all that's between my boat and the bottom is a bit of carbon being pushed onto a stainless steel plate will keep me awake at night worrying.

Logically a bit of rubber against the shaft is the same but somehow I think it'd sleep better with that.....

What to do?

The answer is in your signature

"add alcohol"

Me -I'd never sleep thinking that there is only 1/2 inch of fibreglass in the bottom of my boat to save me from drowning

 

[pvb]

What to do?

If you bought on t'interweb or by phone, you have a couple of weeks to return it for refund under distance selling regulations. Otherwise, sell it on eBay.

 

[Houleaux]

There does appear to be some prejudice around the PSS type seal. There was one fitted to my boat when I bought it (I don't know if it was a genuine one or not) and the engineer who replaced the cutlass bearing recommended replacing it because of his concerns about the design.

He's since fitted a Volvo seal, a Tides Marine seal and a replacement Tides Marine seal. Of all four, the only one that didn't leak within a short time was the original PSS type one!

My experience is certainly not typical - many people are very happy with the lip seals I've mentioned and a Volvo one gave good service on my previous boat - but in my efforts to identify a solution to my own problem I've read a fair bit on here (and elsewhere) about the available options. It seems that PSS seals actually have a very good reputation, but some other face seals have a less enviable record.

If boats were sinking because of them, PSS seals would not still be in production.

What to do? Only you can decide but, if it was me, I'd fit it (or have it fitted) in accordance with the instructions; carry out whatever checks the manufacturer recommends at the intervals they recommend and then sleep easy - knowing I'd bought a quality bit of kit with an excellent track record!

 

[PeterWright]

Route to relaxation

1. Take a large tot of single malt
1. Flog the PSS on e-bay
2. Buy and install a Volvo Penta rubber stuffing box, the only good value component sold unfer that brand name.
3. Burp it by squeezing every time when refloating after drying out.
4. Squeeze a tiny amount of grease in once per year.
5.Settle down and open a good bottle of wine, secure in the knowledge that your sern gland is good for a minimum of 5 years, even if the vessel is used daily (more like 20 years with normal recreational use)

 

[ghostlymoron]

1. Take a large tot of single malt
1. Flog the PSS on e-bay
2. Buy and install a Volvo Penta rubber stuffing box, the only good value component sold unfer that brand name.
3. Burp it by squeezing every time when refloating after drying out.
4. Squeeze a tiny amount of grease in once per year.
5.Settle down and open a good bottle of wine, secure in the knowledge that your sern gland is good for a minimum of 5 years, even if the vessel is used daily (more like 20 years with normal recreational use)

I had a conversation with the guys on the Volvo stand at Southampton boat show re-burping. I can't see how it's done! The rubber is so stiff. I must admit that I've never been on a boat fitted with one and it wouldn't suit me anyway being on a drying mooring. They have the advantage of being simple and cheap and I prefer a lip seal to a face seal as it's more positive but for the moment I'm sticking with the old packed gland.

 

[chewi]

1. Take a large tot of single malt
1. Flog the PSS on e-bay
2. Buy and install a Volvo Penta rubber stuffing box, the only good value component sold unfer that brand name.
3. Burp it by squeezing every time when refloating after drying out.
4. Squeeze a tiny amount of grease in once per year.
5.Settle down and open a good bottle of wine, secure in the knowledge that your sern gland is good for a minimum of 5 years, even if the vessel is used daily (more like 20 years with normal recreational use)

Route to relaxation?
I have to hang upside down in my bilges to get to the stern gland, so wouldn't fancy that after every tide on a drying mooring.

Different situations, different solutions.

btw the radice version of the volvo seal doesn't need burping

I'm happer with my venting PSS and no dependence on a moving O ring seal.

 

[Tranona]

I had a conversation with the guys on the Volvo stand at Southampton boat show re-burping. I can't see how it's done! The rubber is so stiff. I must admit that I've never been on a boat fitted with one and it wouldn't suit me anyway being on a drying mooring. They have the advantage of being simple and cheap and I prefer a lip seal to a face seal as it's more positive but for the moment I'm sticking with the old packed gland.

Nothing difficult at all. You only need to distort the tapered end where the seals are by a very small amount and the air followed by a dribble of water comes rushing out. Just as the instructions claim.

 

[PeterWright]

Burping is simple

No hassle to burp a Volvo seal - all you have to do is get a hand to it, and squeeze gently. After drying out, you will first hear a gentle hiss of air coming out, then bubbling of air / water mixture then silence as just a small dribble of water passes. At this stage , let go and back to the bottle of wine - job done. No need to be able to eveb see the seal while you are doing the job, although that helps the first time, so you can learn what's happening.

If you fail to burp it the seals run a bit hotter - no water cooling - and you might therefore expect a bit shorter life, but not catastrophic failure. The grease aplied once per year will still be providing lubrication.

This seal involves no O-rings. The moulding contains 2 lip seals in series, either of which is sufficient to seal the shaft. In that these seals are integral with the body moulding, there is no possibility of the seal coming unseated in its housing. The rigidity of the moulding provides the pressure to hold the seal onto the shaft, removing the need for steel coil springs normally found in shaft lip seals (e.g. crankshaft oil seals).

Potential problems:

If the shaft has poor finish or damage where the seal runs on it, the seal will wear and fail (but again not dramatically) quite rapidly. The remedy in this case is probably a shaft saver - see your local bearing supplier.

If your shaft is bent, a new shaft is likely to be the cheapest solution, for any type of shaft seal.

If your shaft is poorly aligned, the seal is likely to leak and wear faster, as is any other seal design.

If your shaft has an unsupported length >1.5m between bearings, you will need an extra bearing to eliminate shaft wobble and ensure effective operation of the seal. Volvo are upfront about this in their data sheet, the same is generally true for all other types of seal, but not all suppliers come clean on this. It's not a problem to install a second cutless bearing in the forward end of the stern tube if the P bracket is a long way aft of the gearbox bearing. If you do this, locating the prop shaft positively in two bearings, you need to be particularly careful in aligning the engine to the shaft.

I can see why the Volvo seal would be less appropriate for a boat on a drying mooring. I know the Radice version, it is similar tothe Volvo seal, but, in my mind less well engineered in the moulding. However, it does include a permanent air vent, precluding the need for burping, and so may be more appropriate for a boat that resides on a drying mooring.

Peter

 

[Pye_End]

Volvo burping issue - if it is a pain, then you can buy the Radice seal. It is the same design as the Volvo, except it has a vent pipe.

 

[ghostlymoron]

I agree, Peter wright, the radice one doesn't look as well finished also it doesn't fit imperial sized shafts.

 

[rwoofer]

I had a PSS for 3 years on a Moody 44. Not a drop of water passed through the seal. If you are nervous you can put two opposing (so they balance out) jubillee clips to stop the collar sliding. Double belt and braces then.

 

[uxb]

1. Take a large tot of single malt
1. Flog the PSS on e-bay
2. Buy and install a Volvo Penta rubber stuffing box, the only good value component sold unfer that brand name.

The Volvo seal was my first choice but they don't make one that will fit.

My previous boat had a Halyard seal and it was my first choice but its sadly no longer made.

I am tempted by the Radice though....

 

[Tranona]

The Volvo seal was my first choice but they don't make one that will fit.

My previous boat had a Halyard seal and it was my first choice but its sadly no longer made.

I am tempted by the Radice though....

If you like the idea of lip seals then the Tides Marine seal may be just what you want.

 

[maej]

+1 for PSS

I fitted a PSS to my Sadler 34 replacing a worn out stuffing box. I was after a lip seal but couldn't find one I liked that 'officially' fit a 1" shaft and did not need a pressurised feed from the engine cooling. The PSS 'officially' fitted and could be used with just a vent pipe.

It's only been 6 months but with regular use and quite a bit of motoring it's been fine, nothing but oil in my bilges now.

I was concerned about this type of seal as well at first, but fitting it I was surprised just how strong the seal is. That rubber bellows exerts a good amount of force on the rotor to make the seal, and with the addition of 2 jubillee clips as mentioned by rb_stretch previously it does add that extra failsafe.

When this one wears out I will be replacing with another PSS.

 

[vyv_cox]

My PSS, also on a Sadler 34, has been installed for about eight years now, I think. It has seen a good deal of service, about 2000 engine hours, many thousand miles of sailing and motoring, six months use per year. It has never given any trouble whatsoever, except that the stainless face once became pitted over winter ashore. I'm now careful to flush it thoroughly before leaving it. I turned the stainless face around to use the other side, bought a spare which remains in its wrapping.

A year or two ago, during the course of discussions about the relative merits of different seal types, I managed to find a list of builders who fitted PSS as original equipment. The list was more than an A4 page long, thirty or forty builders from memory, some of them very up-market.

 

[uxb]

Thank you all for your replies.

I will fit the PSS and see how well I will sleep.

 

[DickB]

I have a PSS seal and it is excellent. Great technology and never failed. I fitted it 3 years ago. Much better than splitting grease all over the place. No maintenance as well!!! Excellent bit of kit!

 

[Simondjuk]

Don't panic about it. It's a sound bit of kit.

It takes only a tiny fraction of the specified compression of the bellows to make the seal watertight. Just a few wraps of insulation tape will happily hold the rotor close enough to the carbon to prevent any leaks, even for hours of running. If that works, tightening the grub screws and sticking a couple of jubilee clips on the shaft should be enough for all but the most neurotic.