I am continuing to diagnose and map out a plan to fix the problem described here in another thread. I am seeing bronze flecks dripping from my standard stuffing box:
Quote from: Breakin Away on October 11, 2021, 05:31:41 PM
I think I am going to do some additional inspection and measurements before buying anything. When placed into gear, the torque of the motor pushes the shaft up (slightly) and to port (mostly), causing shaft-to-nut contact
at about 2 o'clock when looking aft toward the nut...
A few additional facts:
I originally discovered this issue when I put a white tissue under the stuffing box to help detect dripping water, and found fine bronze particles. At that time I did not know how long the problem had been happening. I've been putting down the tissues periodically for awhile, but this time I happened to have some sunlight hit the tissue at just the right angle to see some shiny specs, which led me to get out a magnifying glass and take a closer look.
Alignment appears to be fine when the motor is in neutral or not running. The packing nut is well centered on the shaft in this state, with an even 0.01" gap. The issue only appears when in forward, and gets worse at higher RPM (due to higher torque on the mounts).
The stuffing box was replaced in early 2019, along with original bronze shaft (Aquamet G22 upgrade), strut, prop, and coupler. I just inspected the old stuffing box and shaft that were removed at the time, and can clearly see wear patterns that suggest that this issue had been present (and undetected) for quite awhile before 2019. I purchased the boat in 2016, and not sure the surveyor would have detected this.
There are no vibrations in the system, except for idling below 900 RPM (according to the console tach). I have it on my list to recheck the idle RPMs using a strobe on the motor - it might actually be below the M35B spec of 800-1000 (Service Bulletin #236). Getting up to 950-1000 immediately eliminates the vibration. The <900 RPM vibration happens in neutral, so it appears to be unrelated to running gear or alignment...
The first mechanic who looked it over suggested that I need new motor mounts. I am not convinced that this would actually solve the problem, and since the mounts are very expensive I'm looking for a second opinion before getting into a high-dollar replacement. I spoke to another mechanic this week who suggested switching to a "self-aligning" gland. I've searched around to try to see what he's talking about, and the closest thing I found was this:
https://www.go2marine.com/Bronze-Packing-Boxes-Self-Aligning-Gland-Type
So far as I can tell, these are not available for 1" shafts, and the guy said that what he has in mind actually requires tapping into the cooling system. I asked if he was talking about a PSS seal, and he said no, this is something different. So I'm not sure exactly what he is suggesting.
But that got me to thinking, why not just do a PSS seal?
I'd be interested to hear your comments about the various options that you may have used instead of the "standard" packing box? Does anyone have a PSS seal? Other type of packing box?
Countless users out there. There are over 100 references/posts regarding PSS dripless seals on this website. Why not just search and read?
Quote from: Noah on October 24, 2021, 12:28:00 PM
Countless users out there. There are over 100 references/posts regarding PSS dripless seals on this website. Why not just search and read?
I've started reading them. However, PSS changed the design recently, so there may be new comments relevant to the more recent version.
I'm also interested in the "self aligning" one, and haven't found anything about that in my searches, so I thought it would be good to have a thread that compares all the options.
Did all the back and forth myself last December when I put in a new SS prop shaft.
Initially, I thought I would put a new stuffing box on and continue to do it the old "tried and true" way. Even bought a new stuffing box. Even went down a dark and long rabbit hole about whether or not to use the new graphite impregnated flax material, including considering the cautions from Mainesail and others about it possibly leading to corrosion on the (new) prop shaft.
Got down into the aft cabin and started working on it, and changed my mind. Returned the stuffing box, bought a PSS, and installed it. Love the simplicity, and no issues. New PSS units come with the nipple to remove possible ventilation when backing (thereby potentially removing water from the PSS bellows which might cause it to overheat). Attached a piece of hose to the nipple with a hose clamp, and ran it up above the waterline to an overflow/ventilation doohickey as recommended by Mainesail. Located mine just aft and below the sink in the head inside the sink cabinet.
Again, no issues since and as a charter boat I'm out 3X/day, 6 days/week, May-September. I highly recommend changing to the PSS.
Patches
Okay... but why? What were your issues with a "traditional" stuffing box? I have a traditional stuffing box, with GTU packing. It keeps my SS A22 shaft cool and barely drips, even when running at full speed—after 5 years. I pulled the A22 shaft in 2018, as I was replacing my strut (documented here on the forum), and the machine shop said it was true and like new—no evidence of heating or scoring. IMO, the dripless seal adds a potential catastrophic failure point. Let the opinions fly... 8)
Quote from: Noah on October 24, 2021, 04:52:56 PM
Okay... but why? What were your issues with a "traditional" stuffing box? I have a traditional stuffing box, with GTU packing. It keeps my SS A22 shaft cool and barely drips, even when running at full speed—after 5 years. I pulled the A22 shaft in 2018, as I was replacing my strut (documented here on the forum), and the machine shop said it was true and like new—no evidence of heating or scoring. IMO, the dripless seal adds a potential catastrophic failure point. Let the opinions fly... 8)
The mechanic thinks (pending further evaluation) that my engine and shaft are aligned properly, but that the stuffing box and hose are not aligned properly with the shaft, thus leading to the bronze flakes due to stuffing box contact with the shaft. He is suggesting something that will better center itself with the shaft. This could be the PSS, which there is no shortage of information on, or some other type of bronze self-aligning stuffing box, which is different in some way from the current standard stuffing box, but which I have yet to be able to get any information on.
People have told me that there are "horror stories" about PSS, but I have not found any specifics.
I agree that the old fashioned stuffing box works great -- until it doesn't, which is the situation that I am in now.
Break'in—I don't get it?!? I am not a mechanic, but simple geometry should rule here... if your engine coupler, shaft, stern tube and strut are all aligned at the correct height and angle relationship, it should NOT matter what your stuffing box is (i.e. traditional or dripless). I don't think changing your stuffing box will solve whatever "problem" you are having.
Quote from: Noah on October 24, 2021, 07:14:21 PM
Break'in—I don't get it?!? I am not a mechanic, but simple geometry should rule here... if your engine coupler, shaft, stern tube and strut are all aligned at the correct height and angle relationship, it should NOT matter what your stuffing box is (i.e. traditional or dripless). I don't think changing your stuffing box will solve whatever "problem" you are having.
As it was explained to me, everything can look great when you line everything up without the motor running. But when the motor starts spinning the shaft, things can shift. The motor can move to port due to the prop/shaft's torque resistance on the engine, small vibrations on the engine can transmit through the running gear, etc. It doesn't take much movement, because the stuffing box is only 1.02" ID (with a 1.00" shaft). So a movement of 0.01" can lead to metal-to-metal contact.
The standard shaft hose is very thick and stiff, so it will not "give" much. The PSS bellows flexes much more, so that could help things. I'm told that the gimbaled self-aligning shaft will also flex a bit, though I haven't seen its design to see exactly how it does this.
My standard stuffing box seemed to be working fine for 6 years, but suddenly started shedding bronze flakes. It was replaced 2 years ago. I looked at the old one that was taken out, and it looks like that one was showing signs of metal-to-metal contact too. Maybe I just didn't notice it.
I am searching for the solution to this problem. One hypothesis that I have is that my Teflon packing is too soft and wore unevenly over the past two years, so there was no metal-to-metal contact until it wore down 0.01" on one side.
Another possibility is that the engine mounts are worn and allowing more movement of the engine than before. But still, it only takes 0.01" of movement to cause this problem, so I could spend $1200 on new engine mounts and still have the same problem. That's why I'm searching for the answer, since I think $1200 is a lot to spend for something that may not ultimately fix my problem.
Gave you my two cents...anymore, can't help ya...good luck on your quest.
Quote from: Noah on October 24, 2021, 07:44:31 PM
Gave you my two cents...anymore, can't help ya...good luck on your quest.
Your help is appreciated. I've tried adjusting my current setup for the past 6 weeks. I've "clocked" the stuffing box, loosened/re-tightened the shaft hose hoping it would align itself, tightened the nut, loosened the nut, etc. It looks perfectly aligned when the motor's not running, but when I put it in gear, bronze flakes appear.
Now, with winter haulout, I have an opportunity to do something more major, since the minor DIY stuff isn't working. Two mechanics have told me two different things, so I don't know which to follow. All I know is that next spring if it isn't fixed I'll have agony all spring/summer, and then would probably need a midseason haulout to try something else.
For Noah:
"No issues" means no leaks, no chance of scoring the new shaft, and no repacking of flax. Glad to hear there are no adverse affects of the graphite impregnated flax on your new shaft! Wasn't sure how to weight that criticism of the GTU.
Interested though in the "potential catastrophic failure point." A traditional stuffing box relies on a hose connection between the shaft log and the packing gland, attached with some hose clamps. A PSS relies on a bellows instead of the hose, which is in compression, but is still a kind of hose. A SS rotor affixed to the shaft is applying the compression to the bellows, but is snug on the shaft by way of a lip seal, and held in place by doubled up set screws. If the rotor somehow backs off, the bellows will relax and allow some water ingress.
Is this the failure point you are referencing? If so, there is now a collar (which is also available) to attach to the prop shaft and which holds the rotor snug against the bellows. I put this on my new prop shaft as security --in the event that somehow the set screws in the rotor backed out.
If not, what is the "potential catastrophic failure point?"
My worry would be a cracked/torn bellows. It seems like an added complication. Plus, running the burp hose seems like extra work. The traditional log hose seems sturdier. I am a bit of a traditionalist in this regard and my current system has worked well on several boats I have owned (so far), so I am sticking with simple.
QuoteIt seems like an added complication. Plus, running the burp hose seems like extra work. The traditional log hose seems sturdier. I am a bit of a traditionalist in this regard and my current system has worked well on several boats I have owned (so far), so I am sticking with simple.
I agree. Properly aligned engine, good cutlass bearing and properly adjusted packing is for me. I keep a kitchen sponge under the packing nut and the water evaporates before getting to the bilge. But then I'm in fresh water, if I was in salt water and the bilge smelled may change my mind.
Jim
Breaking : I agree with Noah, if you have a ruptured bellows (for what ever the reason) you'll be looking for a travel lift!! :shock:
A thought
I'm no expert on the C-34, but if you have a deck stepped mast the PSS seal makes sense to me. My Pearson has one, trouble free 7 years of ownership, but we replaced it mid this season as the PSS' age was undetermined. As of this summer, you could specify no vent on the bellows and keep it the original way. We chose to run the vent tube and on that boat it was not complicated. We also had a new shaft made, and new flanges, and new cutlass bearing, for little extra cost based upon my conversation with PYI/PSS.
For a keel stepped mast, like my C-34, I chose to stick with standard box, and will be putting in the recently received GFO packing as recommended. It, too, had been maintenance free until I had the other misfortunes and put the shaft out of alignment. However, it did add water to the bilge regularly.
Interesting, the concern about the PSS bellows. It seems to me a pretty rugged piece of hose. What is the the failure mechanism which concerns those about the PSS bellows, but not regular stuffing box hose? Is it that something will come in contact with the PSS bellows which will cause it to fail, because it isn't as "thick" as regular stuffing box hose?
Not sure I understand. I do understand the concern about the rotor backing off, relaxing the bellows, and allowing water ingress. What am I missing?
And WBev: why would having a keel stepped mast vs. a deck stepped mast cause you to choose one over the other? That one stumps me too.
Patches
Patches—my "fear of bellows failure" is NOT based upon any firsthand knowledge of any failures. It is just my vibe that it seems more exposed, is a lighter material, more complicated a set-up and more vulnerable to failure than the traditional stuffing box system. As far as deck step vs keel step: I think what he was getting at was if your goal for having dripless was a "dry bilge"; if you have a keel step mast you will have water coming into the bilge via the mast so the goal of a dry bilge is more difficult to maintain. Albeit water coming down the mast would be fresh water.
Patches - Noah nailed it. The Pearson is dry as a bone, so the PSS keeps it that way. While fresh water from the mast is better than salty (Chesapeake Bay) water, the dampness is not prevented and the "bang for your buck" diminishes. That is the main reason why I chose not to install the PSS.
The rubber boot on PSS is light, and is much thinner than the standard tunnel rubber. It is pliable and quite strong. I knocked into it many times dealing with other issues on the Pearson, including with the pointy end of a wire hanger I had to put in to keep a hose off of it during a week long trip. The real issue I see is if the PSS bellows tears, by its very nature it will likely allow a lot more water in than a standard stuffing tube will. It is made to fill with water and does so fairly quickly. A good rag or something might slow it down some, but it does seem like it would allow swift ingress. (While waiting to be lifted, I did push the bellows aft, separating the seal, and a lot of water came in. This was intentional, purely my curiosity, and the boat was in the slings.)
Interesting conversations around the stern gland wear.
One aspect that should be considered is cutlass bearing wear and what the total alignment is through the cutlass bearing, stern tube and gland and coupling. I have just changed my cutlass bearing and noted that the shaft is not concentric in the P bracket, as indicated by the collets on the removal rig. I studied the old bearing, as I have with numerous journal bearings on large rotating equipment units to determine the shaft alignment, and determined that it appears to have been running in the 11 o'clock position and that there was no rubber left in that area of the old bearing. The new bearing is also compressed more in the same position indicating a lack of concentricity. I have checked the coupling alignment in the past and repacked the stuffing box; but now I have the opportunity to split the coupling and after checking the shaft "journal" area for wear, check whether the shaft has changed its position within the cutlass bearing having been released from the engine coupling.
I would have thought that the problems with the stuffing box may arise from either coupling misalignment or a cutlass bearing/bracket problem since the stuffing box should float on the shaft. If there is damage to your stuffing box gland it may be a symptom of problems elsewhere rather than being part of a root cause, in which case it may pay to look further rather than just change the type of seal.
Nigel
Trillium 2004 Catalina Mk II #1683
I'm certainly no expert on this problem, but as I was reading through this discussion the thought occurred that you might check to see whether the strut that holds the cutlass bearing has ever been bent (however slightly). Could have been from a slight grounding, or maybe by a boatyard accident as it was being placed in a cradle. Since you've already eliminated the more common issues, you may have to look at the more unusual...
Unfortunately it is time to re-awaken the thread. The mechanic who was supposed to fix this problem for me didn't show up all winter, and I just learned that he was terminated and banned from doing any freelance work in the boatyard. I don't know why this happened, but I'm forced to start over again for the third time. This was my second mechanic - mechanic #1 was fired by me last October because he showed up for the job 90 minutes late and smelling of alcohol. So between me and the marina, we're burning through mechanics pretty fast.
I'm glad this thread is here so I can re-read it to refresh myself on my thinking as I reconsider whether to do this myself or find mechanic #3 and hope he shows up during peak commissioning season. I am SO FRUSTRATED because this is exactly the situation I meant to avoid by contacting mechanic #2 last October. I selected this boatyard exclusively because this mechanic worked there, and they had told me, "Sure, bring your boat here for the winter since he does all his work here."
Some other comments:
The cutlass bearing looks great - perfectly even wear, and it's only 3 years old. The shaft rotates freely by hand with no tight spots, which the mechanics said means that everything is in alignment. The stuffing box was replaced in early 2019, along with the shaft (Aquamet G22 upgrade), strut, cutlass bearing, prop, and coupler. I have inspected the old stuffing box and shaft that were removed at the time, and can see wear patterns that suggest that this issue may have been present (and undetected) for quite awhile before 2019. The nut on the old stuffing box is "polished" at the 2 o'clock point, and the inside of the insert that the nut screws into is polished at the 8 o'clock point (180° opposite). The shaft appears to enter the shaft log well centered. So my working hypothesis is that the stuffing box is inserted slightly crooked into the rubber hose, or that the hose itself is very slightly crooked. There is very little tolerance in the alignment, since the nut and stuffing box insert are 1.02" diameter. So if the stuffing box assembly is off by 0.01" at either or both ends, the packing could wear unevenly until the shaft contacts the nut at the fore end of the stuffing box, and/or the aft end of the insert could contact the shaft.
Last season, while the boat was still in the water, I loosened the stuffing box and "clocked" it 180°, hoping that moving it around a bit would allow it to re-center. That did not work. I then loosened the clamps at the aft end of the hose, and tried to clock it, but it was too tight and I didn't want to use any tools on it for fear of shredding or breaking something, which could be catastrophic with the boat in the water. Mechanic #2 was supposed to do this while the boat was on the hard this winter, but he's out of the picture now.
Since the boat is 21 years old, I am thinking I should consider replacing the hose. (I should have had them do that in 2019 when they had the shaft out.) Catalina Direct has thin wall and thick wall versions:
https://www.catalinadirect.com/shop-by-boat/catalina-38/engine/props-etc/stuffing-box-hose-kitw-clamps-1-58quot-id/
https://www.catalinadirect.com/shop-by-boat/catalina-30/engine/props-etc/stuffing-box-hd-hose-kitw-clamps-1-58quot-id/
Do you have any comments on the amount of clearance between the shaft log and the hull underneath? Maybe the thin walled version might have a little more "flex" that could allow the stuffing box to align with the shaft better. Either one looks to be significantly beefier than the bellows in a PSS seal. (I will check to see which thickness my boat currently has.)
Also, if I do this replacement I need to separate the shaft from the coupler. Since both are only 3 years old, I'm hoping they are not too badly corroded together. I'll shoot some PB Blaster into it tomorrow and hope that helps. Do any of you have comments on the shaft puller that Catalina Direct sells?
https://www.catalinadirect.com/shop-by-boat/catalina-28/engine/maintenance/coupler-puller-yanmar-amp-universal-diesel/
I use a steering wheel puller (something like https://shop.advanceautoparts.com/p/performance-tool-steering-wheel-puller-w150/11963067-P (https://shop.advanceautoparts.com/p/performance-tool-steering-wheel-puller-w150/11963067-P)) to push the shaft out of the coupler. I shortened the long center pushing screw due to clearance.
Here's an article on engine alignment that helped me. https://www.yachtsurvey.com/Alignment2.htm (https://www.yachtsurvey.com/Alignment2.htm)
My approach to final alignment in the water was by making many tiny changes until I was happy with the level of vibration. I'd run the engine in gear, make a change (write it down in caseI needed to reverse it) then test again. I did this based on the idea from the article that the system is "floating" and alignment changes when in gear.
How much stuffing box flax do you use?
To eliminate all causes, you could pull the shaft and prop and have a shop confirm everything is balanced and nothing is bent.
I think that, at this point, you don't really know what's true from mechanic #1 or #2. It's possible one or both were somehow incompetent or unqualified. Start with a new mechanic and only describe the symptoms. You may have to go backwards to go forwards.