PSS shaft stuffing box

uncledom · Feb 21, 2017

Watch the video and read the FAQ.
http://www.shaftseal.com/en/about/faqs
On high revolution shafts, and high speed boats engine water is pumped out through the seal not sucked in.

dlochner · Feb 22, 2017

Back in the day, there were 2 versions of the PSS Shaft Seal, a ventilated seal for use on power boats and an unventilated version for sailboats. The unventilated version required burping the seal at launch as an air bubble would form at the inboard end of the shaftlog. Water is necessary to cool the bearings surfaces, the bubble would prevent water from reaching the carbon bearing and it would overheat.

The solution was to stop selling the unventilated version. The vent tube allows air to escape at launch and facilitates water circulation in the shaft log thus cooling the bearings.

The vent tube should be a high quality hose suitable for use below the water line and should end well above the waterline near the center of the boat. The inboard end of the tube is open to allow air to escape. One minor drawback to this arraignments is back flow throw the vent tube in reverse. When the boat is put hard into reverse, water can back up through the vent tube. So long as the open end of the tube does not allow water to spray onto sensitive parts this is a inconvenience and not a significant issue. Maine Sail has describes a way to capture any back flow, the article is on his website, Welcome To MarineHowTo.com Photo Gallery by Compass Marine How To at pbase.com.

Anyway, when installed on a sailboat there is more than adequate water flow to cool the bearing surfaces if the PSS is properly ventilated, no need for positive ventilation.

Maine Sail · Feb 22, 2017

RAD88 said:
I have been thinking about upgrading to a PSS seal and started to wonder. How does it actually work? I understand it has a water hose attached to the raw water in that feeds the engine water pump.
So .. if the water pump is drawing water in thru the sea cock then wouldn't the pump also draw water in thru the PSS seal tube also?
If that is the case then isnt it possible to flood your engine if it wont start and you have the sea cock shut by still sucking water thru the PSS seal tube?
Any thoughts???

On a sailboat the water port is simply a vent to prevent air entrapment in the gland. There is zero need to plumb raw water to a PSS on a sailboat. All you need to do is vent it..

Ken Cross · Feb 22, 2017

I put in a PSS last September and am quite happy with it so far. The biggest challenge is to remove the engine coupling flange and reinstall after installing the PSS. There is a stainless part that attaches to your shaft that rides on a carbon part that is attached to the stern tube. My boat isn't plumbed into raw water, but left open on the high end (attached inside the top of the engine compartment.) It just needs to be high enough that it will not be below water level while you are heeled.

I'm surprised they aren't more common because the cost isn't much more than the hardware for a packed seal.

Ken

JamesG161 · Feb 22, 2017

The PSS seal is the only seal I have seen the DOESN'T use your shaft as a sealing surface. The sealing surface is a very durable carbon composite material and a rotating Stainless plate that is set screwed to your Stainless shaft.

Shaft sealers, like packing or the "lip seal" type have the potential of wearing a grove in your shaft.

Per the PYI technicians, I installed a purged seal, even though for sailboats it is not required.

I must travel about an hour down a silt laden river to get to clear water Gulf of Mexico and have the rare, but possible, use of engine reverse to become unstuck in river mud. When in reverse, you can suck up silt into your bellows, if you don't purge that silt, expect your carbon face to wear excessively.

https://forums.sailboatowners.com/index.php?threads/water-in-engine.175063/page-2

This link shows both @Maine Sail installation and my PSI "tee" to tap into the sea water before the high point vent. Both methods work. I will change the bellows every time I bottom paint.
Jim...

alexco38 · Feb 23, 2017

I have it exactly 10 years now.

quadrille38 · Feb 23, 2017

I had one installed in the spring of 2015.
I began experiencing mystery water in the sump below the engine and went on a search to figure out what was leaking. In the course of that came across a posting here that talked about water being forced up when the engine is put into reverse and the bellows compresses.
I confirmed by putting engine in reverse while at the dock. Revved the engine and went below to check the PSS vent and sure enough water was bubbling up and out of the vent.

Took the article to the service manager at our marina and he called PSS to confirm. He was told that it happens on maybe one out of a hundred boats. (Our friends with a Catalina 355 had one installed and did not experience this). A couple of solutions were offered but they didn't fit my boats configuration.

So our solution was to extend the vent hose up and over to a new through hull discharge. Involved a little hose snaking and drilling for the through hull. Problem solved and no more water fountain.

Love it

Meriachee · Feb 23, 2017

Great product.

Dan_Y · Mar 1, 2017

I used Mainsail's water bottle trick on the end of the vent hose to keep it in the engine compartment. I check it each time after using the engine in reverse. Sometimes water in it, some times not.

RoyS · Mar 2, 2017

Have the old style without the vent. I do burp it at the beginning of each season. PSS recommends that the bellows be replaced every four years. I replaced the bellows after ten years and discovered no visible deterioration in the old bellows. I am very pleased with this product.

PSS shaft stuffing box

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SBO Weather and Forecasting Forum Jim & John

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