PSS Seal Wear Pattern

[Marc14857]

I'm posting this as a curiosity item for others to comment on. I've had a PSS shaft seal on my boat for 10 years with an estimated 700 to 800 engine hours. The seal has worked flawlessly, and I have never noticed any leakage. This is the self venting design via a vent line on the carbon element.

I finally decided to replace the bellows as purely a preventive measure. PSS recommends every 6 years or so. When we took the seal apart I was very surprised to see the wear pattern on the carbon and the SS element as shown in the pictures below. I would have expected both faces to have a very clean mirror finish but the did not. A close look at the carbon face indicated that only about 1/2 of the face surface area was in contact with the SS face. Also the SS face had some type of contamination on it perhaps from the carbon element. Also the carbon element appeared to be chipped on both the inner and outer edges. The outer edges also seemed to be peened over as though they may have overheated. Again I would emphasize that the seal never leaked. I suspect that any potential failure would shown up as a small leak and certainly noting catastrophic but I am curious as what others might think about what might have caused the seal to wear like this.[/ATTACH]

 

[dlochner]

Marc,

My first thought is that the prop shaft is not perfectly aligned with the shaft seal. That would account for the uneven wear pattern.

Some of the pitting on the SS collar looks like crevice corrosion. The presence of which would not be surprising given that there is not a lot of water flow around the SS collar.

Don't have any good ideas about the edge wear on the carbon collar.

 

[heritage]

Send the pics to PSS. They should have some definitive answers.

 

[MSter]

Hi, I too have a PSS and mine is likely 15+ years. I replaced the bellows a year ago and had similar wear patterns. I attribute appearnce of corrosion on the outer edge of the graphite ring to salt. I was able to grind/sand it off to a near new surface appearance.
Also note that the bellows may be slightly off center which can mean an off centric wear pattern on the mating surfaces. Mine did not leak either and still works well.
Mike
s/v Ladylike

 

[JamesG161]

A couple of questions.
1) What is your typical RPM?
2) How is your PSS vented?
3) Water clarity in your Motor cruising.
4) Condition of your motor mounts
5) Does your shaft spin when on a "hull speed" sail?

You don't have to answer, but these are some other factors that affect performance.
________
Did your shaft have minor pitting like on the Stainless Rotor edge?
Actually for 10 years, there is no significant corrosion.
________
What would be polishing the carbon in your water? Sand, silt? Hard to believe but there is a film of water to lube the contact surfaces.

_____
BTW shaft alignment changes with time of use.

Jim...

 

[Parsons]

This is a great question, particularly since I am having one of these PSS seals installed next week! I agree with Dave - send your photos and question to PYI and ask them if they can advise. I would love to see their answers.

 

[Rick D]

I have had mine on for 2000 hours and two bellows changes over 18 years. The surfaces have not been changed. They don't look new but they are better than yours. Makes me wonder if it didn't vent for a while for some reason. Do you still have to burp the unit on the vented design (mine is not)?

 

[JamesG161]

Makes me wonder if it didn't vent for a while

The carbon is designed for a power boat too. Much higher RPM. I would be surprised if mine ever wore out at all. I use a purged seal so I know that the water in the bellow is fresh and flooded.

BTW I am going to use the new "as shown on TV" flex tape and duct tape, if I ever have a bellows leak, in an emergency.
Jim...