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1979 C&C 30 Mk I - 2QM15
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Discussion Starter · #1 · (Edited)
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?
 

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Sea Slacker
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1,789 Posts
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.
 

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Telstar 28
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992 Posts
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.

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?
 

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1979 C&C 30 Mk I - 2QM15
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172 Posts
Discussion Starter · #4 ·
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.
 

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Señor Member
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1,457 Posts
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. :D

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.
 

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Courtney the Dancer
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3,971 Posts
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.
 

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the pointy end is the bow
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6,264 Posts
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.
 

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7,331 Posts
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
 

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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.
 

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One of None
Hunter 34
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9,026 Posts
We put a PSS on my "Older" Oday 30 that has a universal 5416, 2 cyl it shakes allot at low rpms .. doesn't affect the pss at all. Which is designed for a certain amount of misalignment.

It was allot of work getting the hub off the shaft and having to drop the rudder to pull the shaft all the way out for the cutless bearing replacement but it was all worth the trouble (imho) The simplicity of the pss is amazing. I'm glad to have one on my shaft. When we splashed in last week the pss didn't need to be burped since it has that bleed tube attached.
 

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1979 C&C 30 Mk I - 2QM15
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172 Posts
Discussion Starter · #12 ·
It was allot of work getting the hub off the shaft and having to drop the rudder to pull the shaft all the way out for the cutless bearing replacement but it was all worth the trouble (imho)...
The current cutlass bearing I have doesn't have any play, so I wasn't anticipating going through the exercise of changing it. So if I'm just replacing the old stuffing box with a PSS, I shouldn't have to pull the shaft out any further than is necessary to get the PSS bellows and collar onto the shaft correct?
 

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Not A Real Member
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32 Posts
Pss

You are correct on just needing to pull the shaft out far enought to get the PSS shaft seal parts on over the shaft end. Be careful about removing all burrs on the shaft or you will damage the "o" rings on the stainlees steel rotor when you put it on.

My 2 cents....

I have had a PSS shaft seal on my sail boat with a perkins 4-107 for the last few years. The perkins shakes quite a bit at a cold idle and it has never caused the shaft seal to leak a drop. Normally it does not leak at all, and does allow a very dry bilge.

Originally the yard installed the shaft seal vent hose to a "T" in the raw water cooling line. This worked fine until the next time I changed the impeller and the water kept comming out of the raw water pump with the engine thru hull closed.

So next I ran the shaft seal vent line above the water line, and removed the "T". My boat does not go over 8 knots, but the shaft seal made a high pitched squeal that means the seal is not getting water. It also got rather warm. Burping the seal did not help.

Called the company and they confirmed that raw water cooling should be connected to the vent line if the design of the boat might cause a suction in the shaft log. A valve should be installed in the vent line and used to close the vent line when you want to change your impeller, and to regulate the pressure to the shaft seal vent line. The pressure should not be so high as to cause the shaft seal to leak or the bellows to deform. 4-6 psi is about right for mine. You also need to get the hose angle right so there is not to much (or any) side pressure on the vent hose barb or it will pull the seal out of alignment and it will wobble, but still it will not leak.

The seal is not totally maintenance free, but pretty close and the PSS had not been an issue since I had reinstalled the pressure raw water line. Until last week when I was out sailing and heard a metal on metal bang, bang, bang noise coming from what sounded like the shaft area. (My shaft spins while sailing and cannot be locked in gear.) The bellows and the carbon side of the PSS shaft seal was wobbling so hard back and forth as to make the banging sound. This was the first time I saw the PSS spray water into the boat. This was not a large volume of water, as it only sprayed as it banged against the shaft, but it was enough to "stop and fix it now". So I stopped sailing, realigned the PSS by hand and the water stopped. Then I limped back to the dock at under 2kts so the shaft would not spin and called the company.

They said that I must have got something stuck between the faces of the seal and to take 600 grit sand paper and go around both faces 30 times.
Did that and the seal stopped banging and spun correctly. 600 grit sand paper has now been added to the boat stores, as I would have rather done the sand paper refacing at sea when the problem happened.

While I had them on the phone I asked what the life of these seals were under recreational use. They told me to change the bellows every 6 years and I should get 20,000 hours out of the seal.

I have one, I'd get another, but I can understand why some people do not like them, as they may not be correct for every boat.
 
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