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Thread: diesel bug?

  1. #1
    Join Date
    Jul 2003
    Location
    River Itchen, Southampton
    Posts
    7,180

    Default diesel bug?

    I had a problem I think with bug last year. It wasn't blocking the filter but actually blocking the pipe prior to the filter.

    I dosed the tank and blew the line through. And I haven't been using the boat much as I had a bad leg but the few little trips I did were all fine.

    Went to cowes yesterday from southampton. It was a bit bumpy ( gusting 45 knots wind - top end of F8) so the tank got a good agitation - and the engine went again.

    Switched to the other tank and all was well thankfully as I didn't fancy berthing on 1 engine in that wind.

    Filter is clear.

    So what does the panel think? Is it bug? Suggested fixes either way please. There is no drain off on the bottom of the tank nor is there an inspection hatch.

  2. #2
    Join Date
    Sep 2002
    Location
    South
    Posts
    16,741

    Default Re: diesel bug?

    If it were me, I would call in someone to polish/clean the fuel.
    e.g. http://www.cpfuelpolishing.co.uk/ ... there are others.
    Clean out the lines as best you can.

    Then use something like Grotamar 82 to stop it happening again.

  3. #3
    Join Date
    Feb 2013
    Location
    Home: Bristol, Boat: Torquay
    Posts
    185

    Default Re: diesel bug?

    Hi Elessar,

    I had a similar experience shortly after purchasing our first diesel boat, and I didn't know such a thing as an organism that lived in diesel even existed. I completed the deal on Xmas eve, and the boat was lifted and remained on the hard with pretty low tanks for c3 months before it was moved to her home port.

    A few months later at the end of a long journey, with the tanks running low we experienced the same problem.

    Once in port i called an engineer who diagnosed diesel bug.

    On my boat (a Sealine) the connectors from the hose to the fuel tank are super thin. In this example the blockage happened there before any of it gets into the system. E.g the filters appeared to be clear, though we changed them anyway. The engineer simply cleaned the gunk off the end of the pipe, and she was good to go.

    I was told the bug grows in the gap between the top of the fuel, and the top of the tank. At the time i feared it might be difficult to shift, but by following the steps outlined below we never had a repeat occurrence in the following years

    1. I always add Marine 16 when filling up
    2. I keep the tanks as full as possible when leaving the boat for long period of time (e.g. over winter). to minimise the opportunity for growth.
    3. I suspect using the boat and getting everything slopping around in the fuel tank also helps

    DW

  4. #4
    Join Date
    Oct 2005
    Location
    Kent
    Posts
    1,778

    Default Re: diesel bug?

    I had it bad a couple of years ago and the engineers offered options like, remove tanks and steam clean or try to polish diesel in the tanks. However in the end I had a constructive conversation with Marine 16.

    Put a whole bottle in each tank, leave for a few days, this seems to turn the bug to little grit like bits which you can keep an eye on and clean through the glass pre filter. Continue to overdose throughout the season and the little bits left disintegrate. After 12 months fuel was clear and the cost was only circa £200.

  5. #5
    Join Date
    Oct 2003
    Location
    west yorkshire
    Posts
    4,054

    Default Re: diesel bug?

    Quote Originally Posted by Powersalt View Post
    I had it bad a couple of years ago and the engineers offered options like, remove tanks and steam clean or try to polish diesel in the tanks. However in the end I had a constructive conversation with Marine 16.

    Put a whole bottle in each tank, leave for a few days, this seems to turn the bug to little grit like bits which you can keep an eye on and clean through the glass pre filter. Continue to overdose throughout the season and the little bits left disintegrate. After 12 months fuel was clear and the cost was only circa £200.
    +1 re serious dosing. However if the filters are still clean it might be some other cr@p in the tank that has found its way into the pipes. Probably worth running a stiff wire through all pipes that feed that engine. I had a similar problem on a sealine 410/F43 and it was a piece of metal swarf. It got stuck in the switch over valve assembly.

  6. #6
    Join Date
    Apr 2011
    Location
    Boat- Western Med
    Posts
    5,322

    Default Re: diesel bug?

    Quote Originally Posted by DazzyWoo View Post
    Hi Elessar,

    I had a similar experience shortly after purchasing our first diesel boat, and I didn't know such a thing as an organism that lived in diesel even existed. ———/———

    I was told the bug grows in the gap between the top of the fuel, and the top of the tank. At the time i feared it might be difficult to shift, but by following the steps outlined below we never had a repeat occurrence in the following years



    DW
    The tank full bit is to minimise the exposed surface area of cold metal inside the tank for condensation to form and drip down .
    The water that condensers falls eventually to the bottom near the pick up .If there’s a drain cock it can be poured out or at least regularly inspected by running a pint off now and again .

    The “bug “ it’s self is mixture of anaerobic organisms basically airborne , carried in the air .

    You need water without water it can’t proliferated so because Med boats generally stay warm even in winter it’s rare in the Med as if anything it’s a dryer climate not cold and damp .

    Antimicrobial agents can work , indeed do work but like any microorganisms there’s a risk they develop resistance .Hence the suggestion of rotating products.

    The way I tackle it and have done uneventfully for the past 14 years is come from the water side of the equation.
    No water no bug .
    I’ve been adding Startron additives , the idea is not antimicrobial but water dissolution.This “ snake oil “ reckons to dissolve any water in the fuel tanks into the diesel which is reckons then to burn out harmlessly to the engines in the normal way .
    In other words preventing the water / oil interface the “ bugs “ thrive in .
    There are many different “ bugs “ not one hence my scepticism on the antimicrobial approach as I don’t think you can rely on those products to totally eliminate all life .
    Leave 3 % behind , in other words the stuff you choose after 24 hrs kills 97 % , in 7 days that 3 % has proliferated up to occupy the void you kindly made wiping out its competition, back to sq 1 .

    Remember no water nothing lives ,

    Thus far I have no trouble .
    One of my neighbours a CAT Camargue 44 has had to have a fuel barge do a full tank and system decontamination.
    Admittedly it’s only used 4 weeks a year so stood idle for 11 months isn’t helping. So dispute me mentioning the warm less prone to condensation Med, as said the “ bugs “ are airborne everywhere.

    In cold climates- keep the tanks topped up in the coldest season .
    Regulars start and run up to prevent stagnation , keep the pipes patent .
    Add a prophylactic agent - your call on antimicrobial or anti water layer forming .

    Bear in mind antimicrobial resistance if you opt only for the antimicrobial route .
    Those with CR engines spare a thought for the injector pump and injector tips if you elect to do nothing .

  7. #7
    Join Date
    Mar 2016
    Posts
    404

    Default Re: diesel bug?

    I got rid of a bug problem in my tanks only to have pre-filters blocking with flakes of rust the following season, only option was to take out engines and fit new stainless tanks.
    When I got the old tanks home I cut the bases out to find an inch of rust and sludge in the bottom, no amount of polishing was going to help, tanks were 35 year old mild steel.

  8. #8
    Join Date
    Oct 2016
    Location
    UK
    Posts
    672

    Default Re: diesel bug?

    Could it be where excess silicone has got into tank when inspection hatch was sealed down ? I have read that can be an issue on Sealines and more likely to block pipe than filter.

  9. #9
    Join Date
    Oct 2002
    Location
    Essex Bradwell UK
    Posts
    3,445

    Default Re: diesel bug?

    NOTHING IN THE FILTER? I would suspect air, what pre filters do you have?

  10. #10
    Join Date
    Feb 2004
    Location
    Newhaven. East Sussex
    Posts
    597

    Default Re: diesel bug?

    Hi Mark, I had a prob recently, purchased a lucas/ su fuel pump replacement, connected after fuel filters , pumped all fuel out thru filters. changed filters. dosed fuel, refuelled. thx Richard

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