I have had a PSS drippless shaft seal now for 5 years and am quite happy with it. My question is the life expectancy of the bellows and other hardware. The truth be told, other than the annual burp, I have done nothing to the thing. Does the bellows degrade over time? if so what do I look for as an indicator? What other parts can I expect to wear out and again how do I know? Thanks Dave
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Compression Set
Like most anything elastic that sets in one position for a long time it ages and takes on a "set" and the bellows is no exception. After a few years the bellows pressure on the donut decreases and the donut has to be pushed aft a tad. When this needs to be done becomes evident when the signs of water leaks increases. When the dognut is moved aft it is highly recommended to replace the set screws in order to get a good set. The set screws must seat in the hard stainless steel shaft so the business end of the set screw needs to be good and sharp for a good set. I keep spare set screws right beside the coupling so I don't have to go looking. PYI Inc. (Kevin) told me they recommend bellows replacement after something like something like seven years (memory test here) but mine is 14 years old and still going strong. An inspection of it last month at haulout time revealed it still has elasticity, the clamps are in good shape, no visual problems with bellows and it feels strong, so I don't see any need to change it. I'm guessing that their recommended life-cycle of the bellows part may be more a result of our litigious society but then they talk to a lot of people about their products and there are wierd things that no one ever would think of that happen. I'm not connected in any way to PYI other than being a customer of some of their products (PSS, Max-Prop, and last month I installed a R&D Coupling with really good results so far) but I think if you sent your questions to them they'd be happy to provide answers. Check out their web site and the "contact pyi" link.
Like most anything elastic that sets in one position for a long time it ages and takes on a "set" and the bellows is no exception. After a few years the bellows pressure on the donut decreases and the donut has to be pushed aft a tad. When this needs to be done becomes evident when the signs of water leaks increases. When the dognut is moved aft it is highly recommended to replace the set screws in order to get a good set. The set screws must seat in the hard stainless steel shaft so the business end of the set screw needs to be good and sharp for a good set. I keep spare set screws right beside the coupling so I don't have to go looking. PYI Inc. (Kevin) told me they recommend bellows replacement after something like something like seven years (memory test here) but mine is 14 years old and still going strong. An inspection of it last month at haulout time revealed it still has elasticity, the clamps are in good shape, no visual problems with bellows and it feels strong, so I don't see any need to change it. I'm guessing that their recommended life-cycle of the bellows part may be more a result of our litigious society but then they talk to a lot of people about their products and there are wierd things that no one ever would think of that happen. I'm not connected in any way to PYI other than being a customer of some of their products (PSS, Max-Prop, and last month I installed a R&D Coupling with really good results so far) but I think if you sent your questions to them they'd be happy to provide answers. Check out their web site and the "contact pyi" link.
Catastrophe
Some gloom-and-doomers are apprehensive that if the PSS fails it will be a catastrophe. You can see several postings on this in the Archives by typing in "PSS" or "stuffing box." I myself use regular flax and have no opinion on the matter.
Some gloom-and-doomers are apprehensive that if the PSS fails it will be a catastrophe. You can see several postings on this in the Archives by typing in "PSS" or "stuffing box." I myself use regular flax and have no opinion on the matter.
Always will be doom and gloomers
I've read the posts myself. As I stated in my original post, I've had it for over 5 years with no issues at all. I won't discount the Doomers because they have a valid point. I just don't rate the risk as high as they do. I feel that the back-siphing of the head is a greater risk of sinking than the PSS bellows failing. Dave
I've read the posts myself. As I stated in my original post, I've had it for over 5 years with no issues at all. I won't discount the Doomers because they have a valid point. I just don't rate the risk as high as they do. I feel that the back-siphing of the head is a greater risk of sinking than the PSS bellows failing. Dave
7-10 years
Hello Dave, The bellow material itself, being made of Nitral rubber, could last longer then the boat. The thing that causes us to recommend replacement is a compression set. When the PSS was installed it was placed under compression by the rotor being attached to the shaft. This compression over time will cause the rubber to eventually take on a set, thus reducing its ability of pushing the carbon towards the rotor. In order to insure a good backpressure and seal, we recommend that you replace the bellows apx. every 7 to 10 years. I have not read the dome and gloom reports that are being talked about with the others but I can insure you that we see very few if any problems with the bellows. I hear of urban legends from hear say boaters, but we get very few who call with problems. Hope this helps and please let me know if you have any other questions. Kevin L. Woody
Hello Dave, The bellow material itself, being made of Nitral rubber, could last longer then the boat. The thing that causes us to recommend replacement is a compression set. When the PSS was installed it was placed under compression by the rotor being attached to the shaft. This compression over time will cause the rubber to eventually take on a set, thus reducing its ability of pushing the carbon towards the rotor. In order to insure a good backpressure and seal, we recommend that you replace the bellows apx. every 7 to 10 years. I have not read the dome and gloom reports that are being talked about with the others but I can insure you that we see very few if any problems with the bellows. I hear of urban legends from hear say boaters, but we get very few who call with problems. Hope this helps and please let me know if you have any other questions. Kevin L. Woody
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