Originally Posted by KatKokomo
I have a PSS Shaft Seal on my boat.
These seals are very good and there shouldn't be any water leaking into my boat.
But the ones I have are leaking, not all the time, some times when the engines are running, next time at anchor. I had mechanics on board, I spoke to dealer and I get the same answer, the PSS is a 100% watertight and totally maintenance-free seal.
Any sugguestions what I can do next.
I have had one for 15 years, it is 100% drip free, and I still like it! I have had my share of problems that I can share, as well as the cures.
I launched our boat with the "low speed" (= not irrigated model). These have to be "burped" when you launch, EVERY time, or an air pocket at the top of the stern tube may cause the rotor to be running "dry" rather than in water for it's cooling
& lubrication effect. After 5 years of building, and in the excitement of first launch, I may have forgotten this, I'm not sure. (burping is where you rock the bellows' carbon flange, to let some water in, and let the air out of the stern tube).
Some months later, it was chattering a lot, especially at low RPMs, like the rotor was sticky or something. They are VERY sensitive to oil
on the interface! I used a thin paper towel and Isopropyl alcohol to clean between the rotor and carbon flange. This helped for a while. (KEEP IT OFF OF THE RUBBER BELLOWS).
Later, when the noise
came back, I was instructed to polish the interface this way:
Fold over 2000 grit wet/dry sandpaper once, stick it inbetween the rotor and carbon flange, and go around and around for about a minute. This gets petrochemicals off the interface. It helped a lot.
If it started chattering again, I would sometimes loosen the hose clamp on the bellows, and "cock it" to keep the carbon flange centered on the shaft. It has to be just right! The bellows pressure pushing on the rotor, does NOT need to be very tight, Perhaps one pound of continuous pressure!
Seeing fine black specs, indicating a fine carbon mist, around the seal, is normal. It is SO fine, and in SUCH small volume, that it dries on contact, and just looks like a sprinkling of graphite.
Later it did start dripping on occasion, and I just did the above procedures over and over, for a temporary fix.
A year later, at another marina, where we were to stand the mast
... We came back to the boat after a night out, to find 1.5' of water in the main hull! If it hadn't been a Trimaran
, it would've sunk! I bailed, pumped, washed, and dried. Then replaced the pressure pump, eng. battery
, etc. I also installed automatic bilge
pumps & bilge
water alarms. I had originally omitted these, because with our normally "dusty" dry bilge, I didn't think them necessary.
What had happened was, when I was cleaning
compartment previous to the flooding, I turned the shaft by hand, with the rotor. It taking SO little pressure, I never gave the practice a second thought. WRONG! The rotor had later slipped an inch up the shaft when I was running in place, letting in a constant slow stream! Even without such provocation, the grub screw that holds the rotor in place on the shaft, isn't 100% fool proof.
The company sent me a new unit, and a special "reverse direction" drill bit, to get out the old stuck grub screw. (It worked perfectly). I installed the new unit IN the water. Luckily it went off well, but it was a bit risky.
To prevent this from EVER happening again, I put a standard doughnut zinc on the shaft, just on the engine side of the SS rotor, I put a small bead of caulk on it's face, so I wouldn't need to push on the rotor at all, possibly getting it out of square to the shaft. This was a perfect solution! There are fancier SS collar back up devices out there, I saw one here on CF, but a Zinc works fine.
When I sent them the old, somewhat leaky unit, they examined it under magnification, and said I had cracks on the bellows, and small pits on the SS rotor. They thought it had been run VERY hot! HMMM!
This made me think I MIGHT have forgotten to burp it on first launch, running it hard for a week... DRY! I still don't know? The new unit never chattered or dripped at all after that, for the next 7 years!
In '04, while doing a refit
and the shaft was out, I called PYI for a conversation about my installation
. I have a cutlass bearing on the far end of a 3' long stern tube, so very little water flow. I was advised that they don't recommend the NON irrigated "low speed" model anymore, so I upgraded to the new "high speed" carbon flange with a hose barb on it. Otherwise, it is identical. The irrigation hose goes to your engine's up turned cooling
hose loop, but be sure it is on the correct side. You can flood the engine through this hose otherwise! I even put a petcock valve in the irrigation hose, should I need it.
The new model gets plenty of lubricating water flow, the backup zinc is still there, and it has been chatter and drip free for another 7 years now. I like them a lot, in spite of the learning
curve! Obviously, Don't turn the shaft by the rotor, or let it run dry, and install a zinc rotor backup...
The "wet" version is best. If you have one, a CVA joint like ours, makes the installation even better, because the shaft only spins, never shakes... And you need a carbon flange size that has plenty of space between the shaft and inside of the carbon's hole, 3/16" on all sides is OK. I had a friend that had less than 1/8" and his worked fine, but chattered all the time!
By keeping a bone dry bilge, it not only cuts down on mold
, mildew, and smells, but if I get a small eng. "or other" water leak, I know right away, before it becomes a big deal!
Good luck with your problem, and hope this helps. Mark