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  1. #11
    Join Date
    Mar 2004
    Posts
    5,966

    Default Re: Impeller looks a bit tired...

    corrosion dropping back to the impeller, that's a lot of stuff, why is it not being pumped right out of the system when the engine runs ?

  2. #12
    Join Date
    Oct 2002
    Location
    Essex Bradwell UK
    Posts
    3,439

    Default Re: Impeller looks a bit tired...

    120 hours in three years?

  3. #13
    Join Date
    May 2001
    Posts
    15,249

    Default Re: Impeller looks a bit tired...

    Quote Originally Posted by simonfraser View Post
    corrosion dropping back to the impeller, that's a lot of stuff, why is it not being pumped right out of the system when the engine runs ?
    Maybe a combination of corrosion, bits of old anode, salt and calcium build up? We’re all guessing, if the engine has been running at normal temperatures none of this makes sense.

    Vas, was the white stuff in your pics solid or sludge?

  4. #14
    Join Date
    Oct 2007
    Location
    Belgium
    Posts
    4,795

    Default Re: Impeller looks a bit tired...

    this is indeed very strange,
    we all know that salt normally dissolves in water, so there must be something wrong,

    it would be interesting to know if the other pump has the same issue ?

  5. #15
    Join Date
    Mar 2002
    Posts
    17,283

    Default Re: Impeller looks a bit tired...

    Quote Originally Posted by longjohnsilver View Post
    Maybe a combination of corrosion, bits of old anode, salt and calcium build up? We’re all guessing, if the engine has been running at normal temperatures none of this makes sense.

    Vas, was the white stuff in your pics solid or sludge?
    +1.
    There's obviously much more than a normal usage, behind those awful conditions.
    As BartW said, makes me also very curious to hear about the pump on the other engine.

    As an aside, I also wouldn't even consider for a second that "setting" has anything to see with the above situation.
    All blades are worn out, not just some of them - and it's rather obvious that the exceptional wear is due to the unbelievable conditions it was working in.
    Good thing that it was still able to make some water flow!

  6. #16
    Join Date
    Apr 2011
    Location
    Boat- Western Med
    Posts
    5,002

    Default Re: Impeller looks a bit tired...

    Quote Originally Posted by Portofino View Post

    Impeller certainly ready for replacement.I believe there’s different quality with theses as well .

    Do you regularly run them in the winter ? I realise some times it’s on the hard.
    That’s another reason I run mine every month in the off season to exercise the rubber impellers helps prevent a “set “

    But your problem is a draining down pump body .
    MapisM, for clarity regular winter running or lack of it in this case - if you can for impeller health and longevity is “ another “ reason not THE reason of the this particular aetiology.

    Surley regular running would go some way to minimising that build up , like others infer wash / flush it away ?

    Opening this thread up , delving a little deeper and we enter into allowing pencil anodic protected coolers to drain down .
    First pass feel great no seawater what’s not to like form a corrosion POV ?
    Think again - there’s a school of thought if pencil anodes hang in the air all dry then they do not protect effectively.
    This is because for zinc anode protection you actually need a sufficiently concentrated electrolytes surrounding the thing you wanna to protect sos to allow the correct quantity of protective subatomic particles to move freely .

    Layman's terms a liquid circuit .

    Toss in dissimilar metals , the more the greater risk of let’s call it “pencil anode hanging syndrome cooler corrosion “ if they drain down and are left many months air drying inside .
    CAT has had huge issues with this leading to American class action law suits , after that cattle prod they totally redesigned there coolers and materials now all titanium, but with the cop out of “lifing “ them .
    Now a throw away part every iirc 5 or 7 years .That way when not if they fail ,they will be spared another courtroom drama - again !
    Last edited by Portofino; 19-04-19 at 12:41.

  7. #17
    Join Date
    Jun 2011
    Location
    Volos-Athens
    Posts
    4,744

    Default Re: Impeller looks a bit tired...

    a few more things to clarify,

    first engine was running v.cool, producing LOADS of water!

    SF:
    hard to imagine that anode or whatever droppings were coming back down to the OUTLET of the pump and damaging the vanes... On first run I'd expect they shoot off to the CAC endplate and stay there...

    Omega:
    yes only 120h but I actually may be wrong and it was 180, have to check the log, don't remember off hand.

    LJS:
    hard as in V.HARD salt, some would only come off with a bit of hammering on a small screwdriver...

    B&P:
    dunno, that's why I posted it, looks odd indeed. Sorry real work today, will remove the stbrd impeller tomorrow and will post although most of you lot will be on Easter w/e vacation, ours (orthodox easter) is next w/e so I'm "allowed" to work tomorrow and on Sunday

    PF:
    checked levels, pump is almost at w/l level, strainer is above it, hose comes just down from the strainer and into the pump so easy to drain the pump dry if it's above...
    I could reroute the hose so that I have a siphon and both pump and first anode are always full of seawater if it makes any sense. Well I'll do it anyway and see how they come out next year.
    Now, anodic/cathodic protection is too confusing for me right now (had a 20/20 in A-level equiv 38yrs ago but did no chemistry ever since and not even at the uni...), let's see how the stbrd one looks like and we go on from there.

    Only thing I don't recall is the condition of the pump body when I replaced the impeller for the last time, could be that it had some salt deposits which I didn't pay attention to and these have been working and damaging the whole thing now...


    cheers

    V.

  8. #18
    Join Date
    May 2001
    Posts
    15,249

    Default Re: Impeller looks a bit tired...

    Wake up Vas

    How was the other impeller?

  9. #19
    Join Date
    Jun 2011
    Location
    Volos-Athens
    Posts
    4,744

    Default Re: Impeller looks a bit tired...

    zzzzzzzzzzzzzzzzz



    slightly stuck LJS, I always try to have at least one engine running whilst in port, you know just in case...

    So yesterday I managed to put together all the bits back on port engine and fired it up, all's fine, still produces lots of water, running fine.
    I'm rushing the refurb of the generator spot before the yanmar is back onboard hopefully this week, so I've removed old rockwool and perforated panels from bulkhead and ceiling, painted the bilge area and today will be placing the new extra heavy and expensive soundpanels in place.
    Once done, I'll be able to move the gen frame from where it's jammed right now to the new ply gen plinth and this will give me access to the stbrd side of the stbrd engine in order to remove the impeller, so I'm afraid you'll have to wait for one more day or two. This 3-4h a day folded in two is killing my back...

    cheers

    V

  10. #20
    Join Date
    May 2001
    Posts
    15,249

    Default Re: Impeller looks a bit tired...

    Quote Originally Posted by vas View Post
    zzzzzzzzzzzzzzzzz



    slightly stuck LJS, I always try to have at least one engine running whilst in port, you know just in case...

    So yesterday I managed to put together all the bits back on port engine and fired it up, all's fine, still produces lots of water, running fine.
    I'm rushing the refurb of the generator spot before the yanmar is back onboard hopefully this week, so I've removed old rockwool and perforated panels from bulkhead and ceiling, painted the bilge area and today will be placing the new extra heavy and expensive soundpanels in place.
    Once done, I'll be able to move the gen frame from where it's jammed right now to the new ply gen plinth and this will give me access to the stbrd side of the stbrd engine in order to remove the impeller, so I'm afraid you'll have to wait for one more day or two. This 3-4h a day folded in two is killing my back...

    cheers

    V
    Your back might be suffering, but itís good for the soul

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