P.S.S. Shaft Seals Leaking on Older Boats ?

[backcreeksailor]

The deal on my 1979 C&C 30 looks like it's going to be finalized tomorrow. So I'm prepping for the before-splash items I want to address... I was really interested in doing a PSS (Packless Sealing System) shaft seal as my first step toward getting to a dry bilge. But the marina owner is trying to talk me out of it. He said :

"In general with the dripless seals the engine must be perfectly aligned and balanced or they leak like mad".

If it makes a difference, this boat has a Yanmar 2QM15. And out of the water on jack stands it does have a moderate amount of shake/vibration at idle speed. But it smooths out as soon as it's taken above idle.

Does anyone here have any experience with putting a PSS kit into an older boat where alignment and/or balance caused a leakage problem?

[brak]

I have a dripless shaft seal (NOT PSS though, the "rubber seal" type made by Lasdrop) on a boat about 7 years older than that one I installed this one 2 years ago, prior to that the boat had similar shaft seal since about 1994. So far so good - it did not leak.

In fact, I doubt that it can simply "leak". It can catastrophically fail for sure (knock wood, something I try not to think about too much ), or it can work properly and stay dry but it is hard to imagine how there could be a "leak" under usual operating conditions.

[sailingdog]

Is this, by any chance, a single cylinder engine? If so, that's the reason it vibrates at lower RPMs... Even two-cylinder engines vibrate a lot at lower RPMs... I don't see how any reasonable amount of vibration—that would allow a standard stuffing box to work—would cause a leak on a PSS shaft seal. It doesn't make sense.

Originally Posted by backcreeksailor

The deal on my 1979 C&C 30 looks like it's going to be finalized tomorrow. So I'm prepping for the before-splash items I want to address... I was really interested in doing a PSS (Packless Sealing System) shaft seal as my first step toward getting to a dry bilge. But the marina owner is trying to talk me out of it. He said :

"In general with the dripless seals the engine must be perfectly aligned and balanced or they leak like mad".

If it makes a difference, this boat has a Yanmar 2QM15. And out of the water on jack stands it does have a moderate amount of shake/vibration at idle speed. But it smooths out as soon as it's taken above idle.

Does anyone here have any experience with putting a PSS kit into an older boat where alignment and/or balance caused a leakage problem?

[backcreeksailor]

It's a 2 Cyl Yanmar 2QM15... And keep in mind it was started up while still in the air on jack stands, so I'm sure that makes vibration even more audible/noticeable.

But my point isn't that the engine has something wrong with it. I think the engine is fine. I'm just trying to get opinions on whether the carbon to stainless mechanical coupling of a PSS would really be affected in the way the marina owner believes? Or if it sounds more like an assumption from someone that may be biased toward thinking old school flax packing in the stuffing box is best?

BTW... The Lasdrop original looks like it operates just like the PSS. The Lasdrop Gen II and Dry Seal models appear to use bearings so that the carbon/collar seal rotates to reduce friction even further. But the cost seems to be very similar between the Lasdrop & PSS systems.

[PorFin]

Let's see -- would a guy who runs a boat repair yard recommend a) a traditional stuffing box that requires periodic maintenance, or b) a darn-near maintenance free system?

Just pullin' your chain, amigo.

As Dog said, it makes little sense that a properly installed dripless system wouldn't work since the mating surfaces will remain in continuous contact no matter what the shaft is doing.

[xort]

Call PYI and ask what tollerences are required for the PSS

[jrd22]

Since the goal is to have your engine almost perfectly aligned anyway, what's the problem? Is the yard guy saying he can't align an engine very well? I've never heard of any retrofit to dripless having any different issues than an installation when new.

[erps]

Does anyone here have any experience with putting a PSS kit into an older boat where alignment and/or balance caused a leakage problem?

No. The only problem I've experienced is if I get an air pocket in the seal, it makes a racket. That proves just how well they seal if it will hold a pocket of air under pressure under water. JRD22 also let us know that the bellows should be replaced on them about every ten years. I'm taking John's advice and re-do mine next haul out.

[blt2ski]

If you get a newer PSS, they have a air valve with a hose on it to release this air for slower RPM moving rigs. Make sure this air tube is properly installed, or you will have trouble with a siphon effect. I had this the first time sailing with my pss 2 yrs ago. The prop started to turn while sailing, so this created a siphon, and water started to come in via the tube. I was able to pinch the tube off with vise grips and stopped the issue, but not before 20-30 gals of water was in the bilge of the boat. I reread the directions, and the yard that installed the pss, I think it was the first one with this air release! They did not o it quite correct. I fixed it and no issues since.

If the motor is idling rough, there can be spurts of water coming out of the shaft, along with if you pull the rubber seal back ward water can come into the bildge.

From my own experience, the PSS is wetter than a drip style.

Marty

[Selkirk]

Her's my check:
You know the bellows part of the seal? Pull it back and then let it go and see that it "snaps" into position. Mine used to leak a little on occasion and I used to snap it when it was in the water; that sealed it up. I think what was happening is that the surfaces need a little water lubrication in order to seal completely. Not really sure about that part, but snapping it sure sealed it up.
Just make sure it snaps; that'll insure that the two surfaces are being held firmly together.