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Lasdrop Shaft Seal Failure

Discussion in 'Props, Shafts & Seals' started by DOCKMASTER, Jun 3, 2021.

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  1. DOCKMASTER

    DOCKMASTER Senior Member

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    actually it is pretty clearly oxygen deprivation if you have seen it. Electrolysis generally has more longer, streak like pitting and less of a somewhat uniform pitting like this.
  2. DOCKMASTER

    DOCKMASTER Senior Member

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    I agree, I had never heard of the shaft rotation thing either and hence why I missed it. It's literally the last sentence in the manual. They don't specify if just turning the shaft with a wrench is acceptable but I'm thinking not. I would want some water flow to them as well which means starting the engine.

    Lasdrop called me back after my conversation with them and said they really want to see the failed components. I will send them to them and let you all know what else they say. And, of course, I'm contemplating if I want to go with a different type of seal in the near future. This whole experience has shaken my confidence in a component I should not have to worry much about.
  3. mapism

    mapism Senior Member

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    Of course I also have no clue about whether just some manual shaft turn is acceptable or not, 'cause as I said I never heard of this requirement before.
    But basic logic suggests that you are right in thinking not.

    Alternatively, you might consider what I did on my own boat, even if not required by the manufacturer of her seals (i.e. Fluiten, which you probably never heard of in the US).
    What I did was insert an "L" type three way valve into the cooling pipe, connecting it to the onboard fresh water circuit.
    In its working position when the boat is being used, the seal is normally cooled by raw water, as if the valve didn't exist.
    But whenever you want to flush the seal, obviously without running the boat, it's sufficient to rotate the valve and allow the pressurized fresh water go through it instead.
    I think that this very easy modification could take care of the oxygen deprivation risk without any need to actually turn the shafts, let alone run the boat.
    Maybe you could also ask their view on this.
    Should they say that it can't be as effective as rotating the shaft, I'd be very curious to understand why not.
    Last edited: Jun 9, 2021
  4. Tadpole500

    Tadpole500 New Member

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    I believe it is described as crevice corrosion caused by oxygen deprivation. An old school Capt/Eng advised me to always when run engines to rotate shafts fwd rev couple times pump in fresh water to alleviate condition as a maintenance item. Otherwise will cause pitting of shaft surface if left idle for long periods.
  5. SplashFl

    SplashFl Active Member

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    Back at least 20 years I replaced the oem's with PSS Seals that had 0 issues until just a few months ago prior to selling, when one started leaking a little only when running. Never saw anything about rotating shafts but they have a video addressing a non moving leak.
  6. mapism

    mapism Senior Member

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    FWIW, they are among the more popular in EU, together with Tides Marine.
    Both very good products.
    The ones I previously mentioned (Fluiten) are also excellent, and to my knowledge the only ones with no rubber/polymer bellow at all, but mostly used on large boats, often commercial ones that clock astronomic hours.
  7. DOCKMASTER

    DOCKMASTER Senior Member

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    The only reason I chose the Lasdrop seals over the PSS was because I liked the dual water cooling ports of the Lasdrop. This makes it very easy and neat to run a crossover line so you get cooling water to both shaft seals when only running one engine. Hindsight being 20/20 I should have factored in that when only running one engine I'm going slow enough that the seal is getting adequate water through the stern tube and doesn't really need injected cooling water. Alternatively, I could have installed Tee's in the cooling lines to allow for a crossover. I'll see how these Lasdrop seals hold up going forward and decide if I need to make a change.
    TahoeJohn likes this.
  8. DOCKMASTER

    DOCKMASTER Senior Member

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    Boat went back in the water this morning. So far, all good with the replacement seals. Neither leaked a drop. We also verified that both are getting ample water flow to them from each engine. Time will tell I guess.
  9. mapism

    mapism Senior Member

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    Good to hear that you managed to solve the problem, annoying as it surely was, very quickly and effectively. Well done!
    Did you possibly ask the manufaturer if making some water run through the cooling pipes (regardless of whether that's done by turning the engines on or with the flushing system I mentioned) is enough to deal with the problem for which they prescribe shaft rotation?
  10. cleanslate

    cleanslate Senior Member

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    My -2 cents ; perhaps Your seals were from two different production runs and two different production batches one with inferior grade 316 L stainless steel and one with a better grade, being unknown by the manufacture.
    The poor grade stainless steel is the one that rusted out and the other side is a better grade..The poor grade stainless steel is the one that rusted out and the other side is a better grade.
    In other words the manufacture got screwed on a batch of stainless steel and they didn’t know it.
  11. Capt J

    Capt J Senior Member

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    It looks like poor metallurgy. How can it be attributed to not getting enough air, when the part in the picture, is exposed to air in the engine room and the seal is behind the corrossion. Is there a bronze nipple on the stainless shaft seal? Could be getting galvanic corrossion that way. I’m with clean slate on this one.
  12. mapism

    mapism Senior Member

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    FWIW, I also agree that what cleanslate and CJ suggest is a realistic possibility.
    In fact, that's exactly what I already envisaged some days ago in post #8.

    Considering also that the manufacturer offered to resend them the seals and rebuild them for 100 bucks (as per DM post #13), my guess is that they are also suspecting to have been screwed by their supplier and want the parts to prove it.

    I understand the oxygen deprivation possibility in theory, but I don't buy it in this particular case.
  13. Capt Ralph

    Capt Ralph Senior Member

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    Would Stainless draw from the bronze, not give off material to it?
    I also think a bad metal mix in the stainless.
    Never found this in the spring feed waters in my hood.
  14. DOCKMASTER

    DOCKMASTER Senior Member

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    The spring and a few other parts are not exposed to air in the engine room, they are contained within the seal area. The cooling water hose barbs are installed into the carbon graphite housing and no contact to stainless. I’m not aware of any other bronze.

    Putting that aside, you all raise very good questions, similar to mine. And the main issue I can’t seem to understand is, if this were oxygen deprivation, why didn’t it happen to both seals? The Stbd side looks like brand new inside. Both sitting for same amount of time, in same water, etc. Could it be electrolysis on one side only; sure. But all four shaft zincs (2 per shaft) were worn as about exactly as one could hope for.

    It is certainly possible this is a matter of poor material quality. Both the port and Stbd seals are going back to Lasdrop. It will be interesting to see what they say but I’m not holding my breath.
  15. Capt J

    Capt J Senior Member

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    I'd be switching brands. It's poor metallurgy IMO.
  16. Capt Ralph

    Capt Ralph Senior Member

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    Something I think some are missing, carbon fiber assemblies have carbon in it, yes, it conducts.
    It's line in metal nobility, I'm not sure of, without looking the composite formula up and comparing to stainless.
    I assume it will give off vs eat away the stainless but not sure.
    Oh, was any of the carbon assembly deteriorated?
    So, were back to bad metal in the stainless or real oxygen less determined failure.

    Or

    One extra thought, We all know, a scratch in stainless will rust vs a smooth stainless surface will not.
    Was this particular ring not polished or developed a bad surface during / after installation?

    Trash blown on it from the new engine? I don't think anybody understands why I keep saying this.
  17. mapism

    mapism Senior Member

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    Actually I did, and commented on it - see post #11.
    That was before seeing the photos, anyhow.
    Do you still think that's a likely reason? I don't.
  18. Oscarvan

    Oscarvan Senior Member

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    There's a LOT of these doing excellent duty, including on my two shafts.
  19. DOCKMASTER

    DOCKMASTER Senior Member

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    Following up on this issue. I sent the failed seal back to Lasdrop for their input. They inspected and said it is apparent the seal overheated. I was confused on how it could overheat given their are water feeds from both engines. Through several conversations with Lasdrop we determined my seals are plumbed incorrectly. This is a bit frustrating as their are no plumbing instructions in the installation manual. Each seal has two cooling ports. So we plumbed a hose from each engine to one of the ports on the seal on the same side. Then we put a crossover line between the other port on each seal. The thought was if only one engine was running water would flow from one seal to the other side. According to Lasdrop, we need to plumb a line from one engine to seal on same side and install a tee then run the tee line over to the other side and vice versa. So each seal gets supply from both engines.
    I understand the concept the way they have explained it but still not clear what caused the overheat regardless. The only time I have run one engine only was slow speed trolling at around 2 knots. At this slow speed the seals should be flooded through the shaft log regardless of water from the engine. The only thing I can figure is somehow that crossover line created some type of unexpected pressure differential issue and perhaps kept the port seal from receiving adequate flow. There is also some evidence that we already have a similar issue on the port seal we just replaced a short time ago (ugh!).
    So we will modify the plumbing according to Lasdrop and monitor the seals, including with a temp gun at cruise (which we did after we replaced last time). I will also pull the port seal again at next haul-out to inspect and possibly replace it if needed.
  20. TahoeJohn

    TahoeJohn Member

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    Interesting and thanks for the follow-up. Crazy that they didn't include those instructions when in fact such a specific setup is needed.

    Going to check mine now!