PSS Shaft Seal

[Harlen]

The seal is 9 years and 1400 engine hours old and is working fine.

But, how long are these expected to last? Since it is an essential item, I would want to avoid a failure while on an extended cruise.

Boat is being hauled in the Spring so would be the time to change it.

Thanks.

 

[Bendit]

The bellows should be replaced every 6 years according to the manufacturer.
I did mine at 14 yrs and it all looked OK. There is a maintenance kit available for every size.

 

[rochepoint]

From the PSS website:
" PYI recommends that the bellows be replaced once every 6 years on our PSS Type A seals, and every 8 to 10 years on our PSS PRO and Type B Seals. During bellows replacement it is also recommended that the o-rings & set screws in the stainless steel rotor are replaced, as well as the hose clamps. Under most circumstances the carbon stator and the stainless steel rotor will not need replaced."

We replace our bellows at 10 years and it was fine, a kit for bellows replacement is available but you may want to upgrade to the PSS PRO that is now available, that is what we will do in a few more years.......

 

[Ken E.]

I replace the bellows every 6 years, having it done when I'm hauled out for bottom paint. I also have PSS seals on my rudders. The boatyard that does the work told me that about the only problems that they see on PSS seals are bellows-related.

 

[firehoser75]

As stated above, PSS recommends replacing the bellows (kit) every 6 years. When I did mine a couple of years ago, I installed the "Pro" version which has a stated 10 year life. When I bought my boat, the surveyor stated in his report that he could not determine the age of the shaft seal (but it looked in good condition), so therefore he recommended replacing it. My insurance required me to replace it as a condition of insurance. I don't understand how so many people have well over 10 year old seals and can still get insurance? I would wonder if an insurance company might deny coverage if a boat were to sink due to an old (well past the recommended replacement date) seal malfunctioning???
Do not "reuse" the "grub" screws that hold the steel rotor in place, and you might want to install a "retaining collar" available from PYI. This collar helps to maintain the compression on the bellows and it is this compression that is critical to maintaining a "dripless" seal. Otherwise you are relying on the grub screw to hold and maintain that compression, and if it fails, you would have a large leak.
You might consider checking into replacing your cutlass bearings while you have the shaft disconnected from the tranny, especially if you go with the 10 year replacement bellows. When I did mine, I did the cutlass bearings and the rudder seal at the same time. It did not add that much to the labour bill (couple of hours).

 

[STB]

My surveyor reported that my boots felt good, but they hadn't been replaced by the PO or the PPO and the PPPO never mentioned anything about them to the PPO. So, they were at least from prior to 2001 and maybe 1988 or prior.

They were on my list for the next haul out...but didn't make it that long. See photo attached. I temporarily controlled it by pushing the assembly forward and clamping-- and got a haul out with urgency.

PM highly recommended!

 

[Njlarry]

Who has replaced theirs with a tried and true conventional packing gland? Give the possibility of difficulty removing the shaft coupling and maybe then needing a new shaft and dropping the rudder every 6 to ten years for me, removed any advantage of them. Not looking forward to it either way.

 

[DegoRed]

Give the possibility of difficulty removing the shaft coupling and maybe then needing a new shaft

Please explain this?

 

[firehoser75]

Who has replaced theirs with a tried and true conventional packing gland? Give the possibility of difficulty removing the shaft coupling and maybe then needing a new shaft and dropping the rudder every 6 to ten years for me, removed any advantage of them. Not looking forward to it either way.

At least on my boat, there is enough room to slide the prop shaft away from the transmission (a foot or so is all that is needed) without removing the rudder. For me, I would PM the rudder seal at the same time as the shaft seal anyway (10 years), and replace the cutlass bearings every 2nd time which would be 20 years.

 

[steelydon]

I had tolerated a leaking PSS seal for 2 to 3 years and since it was 15 years old I decided it was time to replace it. The yard wanted to go with another dripless seal but after talking with a couple of friends of I decided to go with a conventional stuffing box.

There were several reasons associated with the decision which include, it was $300 cheaper, eliminated the plumbing associated with the raw water cooling required for the seal, with Duramax packing I keep the drips to a minimum underway with none at shut down, I can manage a seal failure without requiring an emergency haulout and no Requirement to pull the shaft for future maintenance.

The stuffing box is easily accessible by raising one hatch and since the Duramax required about 10 hours of run in with several adjustments this made it very convenient. If the seal had been located deep in the bilge under several components I probably would have chosen the dripless.

I have a helm mounted digital temperature gauge that provides constant readings on the stuffing box. I have found that the stuffing box runs about 15 degrees warmer than the dripless.

Steelydon

 

[Njlarry]

Please explain this?

I have not had to do replace mine but I have read experienced pros sometimes find that the one piece coupling will not release from the shaft and the shaft must be cut to withdraw to replace the drip less bellows. This then means a new shaft that must be machined to a new coupling as rust will have formed on the old parts. On sailboats freq the the rudder must be dropped to get the shaft out.
Packing can be replaced without any of this.

 

[Comodave]

Getting the old coupling off the prop shaft isn’t that hard. I press them off and replace them with a split coupling. I took a piece of flat steel stock and drilled 6 1/2” holes in it aligned with the holes in the coupler. Then 6 bolts and a large socket. Put the socket between the plate and the coupler and insert the bolts. As you tighten the bolts the socket will push the coupler off the shaft. I did have to get a 5” nipple as the socket wasn’t long enough to get it all the way off on the shaft I did last week. I rebuilt the stuffing box on the port side last year and the starboard side this year. I too use Duramax packing. Mine doesn’t leak underway or at rest so it is as good as a dripless box.

 

[lwarden]

I've got PSS shaft seals on my boat. One thing I don't like is that at high shaft speeds if you have a little vibration they tend to sling salt water all over in a fine spray. You have to load them up pretty well to stop it an even then, eventually the bellows weaken and they start slinging again. I think this is the cause of some of the corrosion around the transmissions and general vicinity on my boat.
The nice thing about traditional packing is that any seepage are just that drips, they don't spray corrosive fluids around the engine room. I think when the time comes I may go back to a traditional shaft seal.

 

[Comodave]

The PO put these plastic shields on the shaft logs. They would stop the spray and it will just drip off. The photo is before I cleaned up and painted the engine room. You might fashion something like this to contain the spray.

 

[mvweebles]

If your packing glad is easily accessible for service and you're not averse to fairly easy DIY service, my recommendation is a traditional packing gland with modern packing material that is essentially dripless but needs periodic tweaking and checking.

On the other hand, if your gland is difficult to access and service or you are the type who hires all service, a PSS or similar makes sense.

There are some styles of dripless gland where a spare seal can be installed on the shaft so decoupling is not necessary.

Peter

 

[DegoRed]

I have not had to do replace mine but I have read experienced pros sometimes find that the one piece coupling will not release from the shaft and the shaft must be cut to withdraw to replace the drip less bellows. This then means a new shaft that must be machined to a new coupling as rust will have formed on the old parts.

I was assuming this is what you were meaning. Seems than cutting shaft is a thing, and an expensive one at that. I was going to do a write up on this last month as I went through this myself. Mechanic was replacing my PSS glands and could not get couplers off, they spent 4 hours trying with torches, hydraulic presses, hammers, etc., couplers would not come off.

After 4 hours of trying Mechanic tells me he has to cut my shafts and replace them as well. My first question, how much that going to cost? Response was $4K/shaft($8K total). My answer was im not buying new shafts, yall figure something else out. Mechanic says, let me call some fellow mehcanic buddies and see if they have any ideas. To his credit, he called his buddies on speaker phone right in front of me.

First buddy says, if you can't get couplers off, gotta cut the shaft.
Second buddy says, if you can't get coupler off, gotta cut the shaft.
Third buddy says, if you can't get coupler off, gotta cut the shaft.

Fourth buddy says, ah no problem, just get your grinder with cutting wheel on it and cut the coupler off. Rotate shaft so you are looking straight down and coupler with key way looking back at you. Cut coupler right on top of key way. This way if you wont damage the shaft, you just have to buy a new coupler and new couplers come with new key ways.

Now first thing mechanic says, oh this gonna take at least 2 hours per shaft, I bet him $100 it would take less than 30 min per., it ended up taking 10 min/shaft (Yes I timed it) to cut off each coupler. Replacement couplers were $225 each, way cheaper than shafts. Hope this saves some of yall some money in the future.
Since I know yall love pics, here ya go.

 

[catalinajack]

When I had my cutless bearings replaced two years ago, the yard had to cut the old coupling off of the shafts. It my case, then, it was quite difficult. The method you picture would seem to be effective in most cases but, as we all know when it comes to boats, there are never any absolutes.

Getting the old coupling off the prop shaft isn’t that hard. I press them off and replace them with a split coupling. I took a piece of flat steel stock and drilled 6 1/2” holes in it aligned with the holes in the coupler. Then 6 bolts and a large socket. Put the socket between the plate and the coupler and insert the bolts. As you tighten the bolts the socket will push the coupler off the shaft. I did have to get a 5” nipple as the socket wasn’t long enough to get it all the way off on the shaft I did last week. I rebuilt the stuffing box on the port side last year and the starboard side this year. I too use Duramax packing. Mine doesn’t leak underway or at rest so it is as good as a dripless box.

 

[sunchaser]

I had tolerated a leaking PSS seal for 2 to 3 years and since it was 15 years old I decided it was time to replace it.

You're braver than I am, that's along time.

 

[lwarden]

I was assuming this is what you were meaning. Seems than cutting shaft is a thing, and an expensive one at that. I was going to do a write up on this last month as I went through this myself. Mechanic was replacing my PSS glands and could not get couplers off, they spent 4 hours trying with torches, hydraulic presses, hammers, etc., couplers would not come off.

After 4 hours of trying Mechanic tells me he has to cut my shafts and replace them as well. My first question, how much that going to cost? Response was $4K/shaft($8K total). My answer was im not buying new shafts, yall figure something else out. Mechanic says, let me call some fellow mehcanic buddies and see if they have any ideas. To his credit, he called his buddies on speaker phone right in front of me.

First buddy says, if you can't get couplers off, gotta cut the shaft.
Second buddy says, if you can't get coupler off, gotta cut the shaft.
Third buddy says, if you can't get coupler off, gotta cut the shaft.

Fourth buddy says, ah no problem, just get your grinder with cutting wheel on it and cut the coupler off. Rotate shaft so you are looking straight down and coupler with key way looking back at you. Cut coupler right on top of key way. This way if you wont damage the shaft, you just have to buy a new coupler and new couplers come with new key ways.

Now first thing mechanic says, oh this gonna take at least 2 hours per shaft, I bet him $100 it would take less than 30 min per., it ended up taking 10 min/shaft (Yes I timed it) to cut off each coupler. Replacement couplers were $225 each, way cheaper than shafts. Hope this saves some of yall some money in the future.
Since I know yall love pics, here ya go.

Cutting the coupler off as you described is a pretty common solution and well known. I think I would be looking for a new mechanic if he suggested to cut the shaft off.
The big downside to cutting the shaft coupler is spraying metal filings all over the bilge, it makes a mess. Ask me how I know....

 

[lwarden]

The PO put these plastic shields on the shaft logs. They would stop the spray and it will just drip off. The photo is before I cleaned up and painted the engine room. You might fashion something like this to contain the spray.

I plan to do this Dave when I get the boat closer to home. Thanks for posting.

 

[bshanafelt]

another vote for old school packing gland with GFO packing.

When I bought my boat in 2002, the only note the surveyor stated was to 'upgrade' to a dripless gland for the main shaft.

When I got around to doing that, it was fine, although somewhat difficult to actually get it to not leak - took some engine adjustment while in the water to get it to be right.

Then after reading some of the catastrophic problems that go along with a dripless, I reconsidered.

Glad I saved the old gland. I went ahead and swapped it back at the next haul & put in the old fashioned gland this time with Gore or GFO.

Once run in, it becomes a forget it item. Yes, I do check the temp underway once a day, but no drips underway or at rest.


That is one 'upgrade' I would have been happy to sit out.


Incidentally, the old gland makes up for slight misalignment much more readily.

 

[ctjstr]

If your packing glad is easily accessible for service and you're not averse to fairly easy DIY service, my recommendation is a traditional packing gland with modern packing material that is essentially dripless but needs periodic tweaking and checking.

On the other hand, if your gland is difficult to access and service or you are the type who hires all service, a PSS or similar makes sense.

There are some styles of dripless gland where a spare seal can be installed on the shaft so decoupling is not necessary.

Peter

Sureseal units are available at Fisheries. i think it was about 100 bucks to purchase a spare seal and the plastic housing it sits in. (above the price of the sureseal itself.) i prefer those to the PSS seals. Used them on two boats so far and quite happy. One thing that bothered me about the PSS seals is that bellows. When I bought our boat, it was reported by the previous owner that the bellows had been replaced within the last couple years. However the survey I had done called them out and the photo showed that they were checked pretty bad. Insuror required me to replace. No idea if the PO was fibbing, or the seals had not actually been changed, or the product was just kind of crappy. Either way, the net was I had to replace them.

 

[Xsbank]

Suicide grinder, no gloves. Kids, don't do this at home!

Great idea, cut the coupler over the key way. I'm sure I would have screwed that part up.

Comodave, great idea for a puller, well done!

Another thing, a reminder, a pet-peeve, NEVER use carbon packing. That's designed for industrial pumps. Just what you need on a boat, a battery hidden inside the shaft part that makes the wheel go round.

 

[psneeld]

Cutting the coupler off as you described is a pretty common solution and well known. I think I would be looking for a new mechanic if he suggested to cut the shaft off.
The big downside to cutting the shaft coupler is spraying metal filings all over the bilge, it makes a mess. Ask me how I know....

Yep, well known and publicized.

I find very few opinions from too many recreational boaters and pros worth a dang any more. Have to research everything in depth.

Part of the problem is so much to know, so many systems, tech advancing by leaps and bounds... it is tough to stay up on it all.

But shaft couplings????...pretty basic to be saying cut the shift unless the other tricks have proven useless...which I have never heard that cutting along the keyway didn't work.