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Thread: Diesel bug

  1. #11
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    Default Re: Diesel bug

    Quote Originally Posted by CAPTAIN FANTASTIC View Post
    I used to get it a lot on my Land Rover car in winter when the temperature was below -8C.
    Are you sure that wasn't waxing?

  2. #12
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    Default Re: Diesel bug

    Captain F, what you got in your LR was unlikely to be bacteria, but most likely to be waxing which entrains debris in the filter(s)- hence the colour. Bacteria much prefer warm temps.

    The idea of petrol being poisonous to diesel bug is, frankly, untenable. Petrol contains ethanol, which is a food for bacteria.

    Bacteria can grow in diesel tanks which do not have water entering e.g through a leaking filler. Water is an aid to bug growth, not a pre-requisite.
    I think, therefore I am. I am, therefore I sail.

  3. #13
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    Default Re: Diesel bug

    Quote Originally Posted by jdc View Post
    I don't think my advice would be different. It's not that I don't believe that one can get organisms in the fuel (provided there's some free water as well), just as no GP doesn't believe in bacterial infections. But the best way to go about prevention and treatment may not be - I argue is definitely not - regular dosing with sub-lethal amounts of a biocide. I genuinely welcome debate on this, but real industries which really care about this such as rail and air transport do it differently and more scientifically. I suggest that we could learn from them.
    I've done a fair amount of testing (lab and field) of biocides, and there is truth in what he says. In fact, I built water treatment plants to biodegrade the waste, using acclimated bugs. So yes, I would say keep the tank dry, watch you filters closely, and treat annually or so, depending on use. Treating after they are well-established is not a good answer, since the dead bodies still need to come out.

  4. #14
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    Default Re: Diesel bug

    Quote Originally Posted by sarabande View Post
    The idea of petrol being poisonous to diesel bug is, frankly, untenable. Petrol contains ethanol, which is a food for bacteria.
    Actually, he is correct. In shock doses it is quite lethal. I've tested this at lab and refinery scale. There is a reason you don't get bug in petrol. This is why some non-biocide treatments are effective in controlling bugs; it's not the additive per se, it is the specific distilate they used as a carrier. Often, I suspect, this is accidental!

    The trick is getting the dose right. Too much and you ruin the diesel just as sure. Just a few percent.
    Last edited by thinwater; 12-07-18 at 14:22.

  5. #15
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    Default Re: Diesel bug

    Quote Originally Posted by jdc View Post
    I differ. The advice from the manufacturers of the treatments is, unsurprisingly, to buy as much as possible and use it frequently, their justification being 'that's what they do on aircraft'. However this is being economical with the truth. The IATA guidance prohibits use of biocidal chemicals for routine preventative treatments, and also only recommends the use of biocides once a sample of what is suspected to be contaminated has (i) been re-sampled 24hrs later and (ii) has been sent off to a testing lab which has confirmed infestation.

    What routine dosing in sub-lethal quantities is doing is at best nothing at all (except extracting your money) and at worst engendering undesirable organisms which are resistant to the previously effective biocide. It's a bit like dosing livestock with anti-biotics and is one of the key reasons why fuel isn't so dosed by the refiners or distributors (1).

    The manufacturers may claim that their chemical is different, but in that case it's (i) not on the list of substances approved for aircraft use (invalidating one of their key claims about it) and/or (ii) ineffective (so building up resistance doesn't matter).

    Of course loads of people will claim to have dosed for years with no ill-effect and so say that it must be working. Well, I've been whistling at magpies all my life and, you know what, I've not yet been abducted by aliens so it's clearly working...

    (1) The other reason is that the dose rate is critical and if already in the fuel it would risk a double dose. Again, think about antibiotics: they are prescribed with instructions to take a precise dose (a pill of a precise size every 6 hrs or whatever) and to finish the course. You're not told 'oh, just take a pill from time to time whenever you remember or can be bothered..'. So bad practice is once more promulgated by the manufacturers of the biocidal treatments.
    There’s a lot of truth in what you say, but all additives are not the same and all are not simply biocides. Hence, one of the best grade fuels one can buy at the moment is Esso’s FAME-Free diesel produced in Fawley (MOD approve this AFAIK) which as it happens is pre-treated with Soltron. Soltron of course works slightly differently to Marine 16.

    But it’s also worth pointing out that low dosage biocidal applications followed by shock doses as required are quite common in practice, and for example are standard practice in swimming pool maintenance.
    Last edited by dom; 12-07-18 at 14:23.

  6. #16
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    Default Re: Diesel bug

    I know a lot of people suggest a small amount of petrol in the diesel, but I would be very careful about this solution, diesel fuel is a lubricant and many components in the diesel engine rely upon this lubrication, Petrol is an abrasive and can if used excessively degrade the lubricant value of the diesel, particularly the diesel pump which is not a cheap item to replace. After an attack of the dreaded bug, I drained the tank by siphon which managed to suck out most of the slime in the tank then flushed through the tank and system as far as the fuel intake on the engine with fresh diesel with additive by connecting an air hose to the tank and pressuring the fresh fuel through. I no add some ‘anti-bug’ additive to the fuel at the start of the season and so far have been free of it now for several years.

  7. #17
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    Default Re: Diesel bug

    Quote Originally Posted by thinwater View Post
    Actually, he is correct. In shock doses it is quite lethal. I've tested this at lab and refinery scale. There is a reason you don't get bug in petrol. This is why some non-biocide treatments are effective in controlling bugs; it's not the additive per se, it is the specific distilate they used as a carrier. Often, I suspect, this is accidental!

    The trick is getting the dose right. Too much and you ruin the diesel just as sure. Just a few percent.
    I was simply stating that petrol is toxic to bug. But you wouldn't catch me putting it in my tank, because it is bad for wear, and because it can eaily make the diesel explosive. It only takes about 2-4% to lower the flash point into the ambient temperature range. Very bad, since the systems are not designed for that. So no petrol in my tank.

  8. #18
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    Default Re: Diesel bug

    The fuel tanks on boats used to be provided with a dirt sump with provision for occasional draining. This ensured that there was little or no water lurking in the bottom of the tanks. The "bug" thrives on the interface between the water and the fuel. Take away the water, and you won't get the bug.

    Modern shallow hulls have made it more difficult for main fuel tanks to have sumps, but there is little to stop the fitting of a modest sized day use tank, with a dirt sump and drain, thus giving the further advantage of a gravity feed.

  9. #19
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    Default Re: Diesel bug

    Quote Originally Posted by thinwater View Post
    I was simply stating that petrol is toxic to bug. But you wouldn't catch me putting it in my tank, because it is bad for wear, and because it can eaily make the diesel explosive. It only takes about 2-4% to lower the flash point into the ambient temperature range. Very bad, since the systems are not designed for that. So no petrol in my tank.
    Interesting, if you read about truckers that used to do the overland Middle East runs they claim to mix quantities of petrol with diesel to prevent waxing.

  10. #20
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    Default Re: Diesel bug

    Quote Originally Posted by jdc View Post
    (1) The other reason is that the dose rate is critical and if already in the fuel it would risk a double dose. Again, think about antibiotics: they are prescribed with instructions to take a precise dose (a pill of a precise size every 6 hrs or whatever) and to finish the course. You're not told 'oh, just take a pill from time to time whenever you remember or can be bothered..'. So bad practice is once more promulgated by the manufacturers of the biocidal treatments.
    It's not like a bacterial infection in the human body. There is no downside to over-dosing, other than cost.

    Richard

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