Another PSS cautionary tale

Alan Gomes

Alan Gomes

Sustaining Partner
I pass this along for those of you who have the PSS in case you might find yourselves in a comparable situation. While a number of (evil) stars would have to align for this to happen to any of you, it's probably still worth keeping it in mind.

(Some of you who also frequent SBO--such as Loren--may already be familiar with this thread, which has been quite a saga for this poor gentleman getting his old Perkins engine up and running. And now this added complication of water intrusion from what should have been a simple water pump swap has added to his headaches. I must say that I find his equanimity impressive throughout this thread.)
 
driftless

driftless

Member III
Blogs Author
Stories like this make me happy about my old school stuffing box. I keep contemplating prophylacticly repacking it, but since the drip rate is good I default to the ain't broke don't fix it school of thought.

Can someone please explain to me how the PSS would be plumbed into the heat exchanger?
I've understood there to be a hose to vent air bubbles, but didn't realize it could possibly be plumbed into the cooling system.
To my mind it seems like this would likely be a situation of exhaust siphon, not involving the shaft seal?
 
Christian Williams

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
A friend of my mechanic, was called and he found that the pump hose to the heat exchanger was the source of the water. It had been left to dangle while the Raw Water Pump was being fixed. When it fell beneath the level of the Heat exchanger, a siphon event occurred and water flowed up from the PSS Shaft Seal through the Heat Exchanger and out the pipe dumping the water into the bilge.

Was the PSS plumbed to the heat exchanger? Who knows.

I have uncovered an interesting sequence in my own recent PSS event, depicted at length in a video soon coming. It goes like this:

Why plumb a sailboat's PSS to a thruhull and hose, when that is not necessary for vessels that don't go fast, like motorboats? Of the three options for PSS installation on sailboats, why choose that one?

Option 1: no PSS plumbing. Burp unit by hand every launch. However, failing to burp the seal can cause it to burn out. Owners have to be responsible, especially of boats hauled often. They weren't. So "protection" was recommended.

Option 2: Vent the PSS with an air line, essentially vented loop. This keeps water in the unit all the time and requires no thruhull. However, such a vent hosemust rise above the max waterline when heeled. Usually a cable tie used to keep the end of the vent up at cockpit level . However, cable ties fail over time. If such a vent line falls below the waterline, the PSS floods the boat. According to second-hand conversation with PSS, half a dozen boats were sunk that way, causing service bulletins. Enter Option 3.

Option 3: Thruhull and irrigation line. This was considered "safer in the long run," because it guarded against owner failure to burp or inspect. And because access is often or usually difficult for shaft seals, especially, I am told for motorboats, and boats with V-drives.
Therefore, PSS for a while recommended all installs use thruhulls and hose to a fitting on the stator.

Things are less clear-cut today, I am told, and all boatyard policies have drawbacks.


 
Alan Gomes

Alan Gomes

Sustaining Partner
Christian Williams said:
Option 1: no PSS plumbing. Burp unit by hand every launch. However, failing to burp the seal can cause it to burn out. Owners have to be responsible, especially of boats hauled often. They weren't. So "protection" was recommended.
Click to expand...
If I had one of these I'd go with Option 1, hands down. Then, before I sold the boat, I'd add some kind of blinking neon sign in the engine compartment, with a stark warning about burping the PSS after launch, for the benefit of the next owner.
 
Jerry VB

Jerry VB

E32-3 / M-25XP
driftless said:
Can someone please explain to me how the PSS would be plumbed into the heat exchanger?
I've understood there to be a hose to vent air bubbles, but didn't realize it could possibly be plumbed into the cooling system.
Click to expand...
Pure speculation but the only thing that makes sense to me is that the raw water intake was properly plumbed into the cooling system. Some time later the PSS was installed and the vent was (improperly) plumbed by "T"ing it into the cooling system thus "taking advantage of" the existing thruhull.

The discussion of the wisdom and necessity (or not) of venting a PSS to a thruhull is in a master thread.
 
Nick J

Nick J

Sustaining Member
Moderator
Blogs Author
Small world, this boat is a few slips down from me and I was there while they were wrapping up the pump out process. Glad they cought it in time
 
peaman

peaman

Sustaining Member
Christian Williams said:
However, cable ties fail over time. If such a vent line falls below the waterline, the PSS floods the boat. According to second-hand conversation with PSS, half a dozen boats were sunk that way, causing service bulletins. Enter Option 3.

Option 3: Thruhull and irrigation line.
Click to expand...
Hmmm. Extra cable ties (or better) on the vent line secured several inches above the cockpit deck in an often-accessed locker, versus a new through hull. I'm thinking that if option 2 is not good enough, I should be shopping for a stuffing box to replace my PSS seal.
 
Bolo

Bolo

Contributing Partner
Christian Williams said:
There is now a fitting for dripless air vent lines designed (apparently) to solve the problem.

View attachment 47856
Click to expand...
I have the vent hose coming out of my PSS dripless and then attached to the underside of the cockpit deck in the the engine compartment, above the water line. So the Hy-Vent would attach to the end of that vent hose (where I can see water in it about half-way up) to prevent water coming out and sinking the boat? I imagine that this would also need to be attached, vertically (with the adjustment screw up) in order to work properly Correct?
 
A

Anzac

Member II
Christian Williams said:
I think so. Sounds like an easy addition.
Click to expand...
Just watched your video Christian. That ball value was scary and not supposed to happen. You would have had to improvise, adapt and overcome and that's why your toolboxes continue to grow as does all ours lol. Glad you got things sorted and did not sink at the marina.
 
Christian Williams

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Sure better than a single cable tie installed nine years ago by a guy who couldn't actually find a good place to attach it.

Not gonna "fall into the bilge."
 
Loren Beach

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Christian Williams said:
There is now a fitting for dripless air vent lines designed (apparently) to solve the problem.

View attachment 47856
Click to expand...
On the off chance that a given boat model could hold some air in their shaft alley, this does look like the real solution. Thanks for the info!
Since our O-34 has not experienced an air entrapment problem in about thirty years, no change contemplated for us... but all models are a little different.
Classic proof that "YMMV". :rolleyes:
 
Loren Beach

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Note to Nick: thanks for the photo showing where you mounted the fire extinguisher. I had to create a location under a cockpit seat hatch for ours, after a recent survey demanded one. It's a bit of a challenge -- gotta have it "handy" and yet protected from splashes and assaults by other stored gear.

(Love this site for learning/sharing information, both for convenience and for safety.)
 
Nick J

Nick J

Sustaining Member
Moderator
Blogs Author
Loren,

Thanks for noticing. I'm actually not a fan of where the fire extinguisher is. I have to remove it every time I change the trash bag and the bag still snags on the extinguisher mount.
 
You must log in or register to reply here.
Top