air in PSS dripless seal

[Earl Miller]

I have been getting a loud noise from the shaft area of the boat off and on now for a week.  Several posts point to air in the PSS shaft seal bellows as a possible cause.  As suggested in the posts I have burped the seal and it does seem to solve the problem for a day or so but the noise has been returning on a regular basis.

I talked to Dan in the customer support dept of PYI Inc, the manufacturer of the PSS seal.  He asked what type of boat I had and when told it was a C34 said that the hull design on the C34 was a know problem with their seal.  Apparently it can pick up air easier than other hull designs.   They do have a new design for the carbon half of the seal that vents the bellows through a small tube .... he offered to provide the new part at no charge.

Has anyone else had a similar experience with a PSS seal on a C34?

[td]

Peregrine has the old style PSS shaft seal.  I have not had any problems, including any noise, in the 6 years I have owned the boat. I 'burp' the seal only after haul-outs, and after a diver cleans the bottom and/or changes zincs.

[Rocco]

Earl,

I installed a PSS shaft seal on Geneva last year and did install the vent hose model (they no longer sell the none vented).  After much deliberation I ran the vent hose over the muffler through the bulkhead and then up into the port lazarette where it is well above the waterline and very well protected (it comes up at the very front of the lazarette beside the bulhead seperating the lazarette from the head compartment and is clamped there, well out of the way.  i've attched two photos showing the seal and vent hose over the muffler and the the hose routed up to the lazarette (under the head sink next to the fuel lines).

Hope this is helpful,
Rocco

[RV61]

Earl,
My 1986 has the PSS with the vent tube however the tube is capped. Based on the pictures above I think I will add this project to the list. I occasionally get a squeal maybe once or twice a year and burping it has taken care of it. At one time I was hearing a knocking or tapping sound and thought it had to do with the seal however discovered I needed shaft aligned. Is the noise a squeal or a tap?
Rick
 

[Jeff Tancock]

As with Peregrine, I have had the old PSS installed for 8 years and had no issues what so ever.

[John Langford]

I used to get regular "chatter" (as they describe it at PYI) from the PSS shaft seal on my C320 but the seal on my 34 has performed flawlessly for 4 years. I am told that if you have divers around the boat the seal can trap air bubbles and require burping. It's apparently a significant issue in places where the boat bottoms are cleaned regularly by divers.

[Bob Kuba]

I have a PYI Max prop on my '94 Mark I, and after moderate to agressive reverse thrust, I need to burp the seal, otherwise a small chirp develops. I have an older seal without the vent hose. Otherwise, it works great.

[captran]

When Voyager was in the Bahamas I had that exact problem, a high squealing noise.  The first time it occured I was paniced, as I didn't know what the heck was the problem.  When cruising there I found myself burping the PSS almost every day as a way to prevent that from happening.  It seemed like it occured more often if I was rolling in a cross sea.  I guess Voyager likes the Northwest alot more.  She runs about 20 degrees cooler, never going over 160 degrees and I had only one squeal during 7 weeks of cruising for which one burping solved the problem.  I figure one burping in that amount of time isn't too much of an inconvenience.  I do still notice a line of graphine that is distributed in a line along the bottom and sides of the compartment.  Do others have that same line?

[John Langford]

The squealing or chatter episodes are not always or even most often caused by air in the bellows. My understanding from chatting with the PYI folks is that the most common cause is the intrusion of a small grain of sand or sea flotsam on to the interface between the SS doughnut and the graphite. This causes the interface to destabilize briefly and spray a thin line of graphite and water onto the inside of the hull and muffler, etc. The water spray usually clears the offending particle away and the shaft seal returns to normal operation without requiring burping.

By contrast, if you get air in the bellows, the shaft seal unit will get hot because it is not being lubricated by sea water. This does require burping. Assumedly, if the situation went on unnoticed for some time it could cause more significant damage. But I have personally never heard anything about the unit failing because of lack of water.

[Earl Miller]

Randy, I had the same line of graphite sprayed from the seal.  As John suggests, it may have been caused by debris getting into the seal and destabilizing it enough for the carbon to break down.  This may have caused a deposit on the surfaces of the seal as well ... further destabilizing it.
When I told Dan at PYI about this he suggested that I clean both surfaces in the seal.  This is done by folding a small piece of 600 grit Emory cloth in half and placing it between the carbon and stainless plates of the seal (water leaks out but not enough to worry about).  I then rotated the Emory cloth 360 degrees with the seal closed sanding both surfaces all of the way around.  This was done four times (Dan was very specific about four) and then the seal was burped to remove the resulting debris.
I have not had any chatter since doing this (knock on wood).  Dan has since sent me a new carbon plate with the vent and bellows at a very reasonable price.  This will be replaced when the boat is hauled to paint the bottom in the spring.

[captran]

I'll give that a try next year.  Hope you are enjoying Diamond girl.  The PO seemed like a knowledgable owner.  We met them briefly at the dock  by Deception Pass.