A word of warning for the unwary.

[mick1211]

I pride myself like most boat owners, with maintaining my boat to the best of standards to protect my investment, but alas, we can all fall foul on occasions and this year it was my turn !
The boat has been used very little since October but I meticulously go to the marina once a week to start the engine and warm it up and have had no problems until this week. When I tried to push the revs to about 2000, the engine wasn't happy and the white smoke from the exhaust confirmed there was a problem.
A quick look at the diesel pre filter as a first stab at finding the problem shocked me, as the extent of the filter clog was surprising to say the least (see the photos).
My immediate thought was the often talked about 'diesel bug' and a call to the Marine 16 experts, confirmed that this was the likely problem.
I have been re-assured that it probably will not need the tank removed for cleaning and a couple of specific 'fuel treatments' will likely cure the problem but only time will tell. If there are any residual problems that's what I'll do.
The point I am making is that I'm sure a lot of boat owners will turn up early in the year not expecting problems, just as I was and feeling confident that the regular starting was enough to provide the re assurance that all was well. Just imagine if I had managed to get to sea, full of confidence in my boat, only to end up without a working engine 3 or 4 miles off.
Incidentally, before, a well wishing reader tells me I should have used a preventative treatment, I usually do at every fill up but i know that I didn't late last year with the foregoing consequences Duhhhh....!!
I've learnt a valuable lesson and following the amount of time I've spent researching the phenomena I almost feel like a 'diesel bug' expert.
Have a good season and check your filters and your fuel......................

[fozally]

Know nothing about diesel marine engines. What is diesel bug ?

[mick1211]

Diesel Bug

The so called 'Diesel Bug' is in fact a number of things including bacteria , fungus and yeasts which are more than likely present in all modern diesel fuels as modern diesel contains a percentage of bio diesel.
When water is present in the fuel tank, even in the small quantities that can be caused by condensation, the 'bugs' respond by reproducing rapidly.
They have a very short life (hours) and subsequently die and sink to the tank bottom to form a sludge which also contaminates the exposed sides of the tank.

The longer the conditions are right and the problem not dealt with, the worse it becomes. In my case this problem has occurred since last October with the results I have described.

I hope this gives you some idea of the cause but the detail is very scientific and I'm not at that level of expertise yet !!

[Paul_h]

Mick
bad news and looks nasty, do you have pre filters fitted off engine ?
i personally do not like the idea nor do i use any preventive treatment stuff.
i have never used it, this is purely personal choice, i chose to go with 2 off engine filters, and the on engine, keeping the tanks full.

if you don't have pre filters but have the room i would strongly recommend it. These filters clean the fuel and help protect the injectors and gives a cleaner burn.

[URL=http://lnk.splashurl.com/1dfA


[URL=http://lnk.splashurl.com/1dfB

the first is a bulk knock out 20-10 microns, then 10-5 microns with a 5 micron on the engine. the black tube on the outlet bypass goes to a vacuum gauge which tells me the filters need changing, instead of guessing or changing on a hours used.

they are both water knock out. when the vacuum gauge reads between 8-10 then i change the filters.
i find this has been spot on.

With 640 litre tank, my engine pushes 68 gallon an hour through the filters, while 24 gallon/hr of that gets burnt, thats a lot of cleaning. this is from the fuel curve at WOT. obviously less gallons getting circulated at lower revs

i am not saying it stops these critters, but this is how i chose to try and manage it.
Full tanks is a main player, with quality filters and regular draining of the 2 filters. The vacuum gauge can be fitted to each filter, but i chose to run a tube to a helm gauge, i am however going to fit a local gauge on the first filter.

i use Fleetguard stratapore premium filters on all, both off and on engine, all spin on.

thought i would mention it to give you some food for thought. i think once the initial set up cost is out of the way, its a cheap way to look after your engine

Paul

[drifter]

Hi Mick, nice boat bye the way.
The pics certainly suggest a bad diesel bug contamination and I reckon you may have to clean out the tank and purge the entire system.
Boats with stainless steel or galvanised fuel tanks are usually more prone to condensation unless they are kept well topped up but am I right in thinking yours will be of a poly construction?
Diesel bug is rarely mentioned within the Royal quays fishing fraternity and I feel it's because most of the lads buy their diesel from the Royal Quays fuel berth. Everyone gripes about the cost of diesel but at least you know it's good stuff and free of any contamination. Some marinas don't have a fuel facility and as a consequence the boat owners have to source their diesel externally. It's always tempting to buy cheap cherry "with no questions asked" but without really knowing it's origin you could be buying trouble. Not suggesting you've bought some dodgy stuff but just pointing out to other boat users that "economical" purchasing could ultimately end up costing a lot more.

[alcaucin]

is there any way/space to fit a low point water drain to the tank which may help to prevent water getting into the fuel lines and building up a water level in the tank

[fozally]

The so called 'Diesel Bug' is in fact a number of things including bacteria , fungus and yeasts which are more than likely present in all modern diesel fuels as modern diesel contains a percentage of bio diesel.
When water is present in the fuel tank, even in the small quantities that can be caused by condensation, the 'bugs' respond by reproducing rapidly.
They have a very short life (hours) and subsequently die and sink to the tank bottom to form a sludge which also contaminates the exposed sides of the tank.

The longer the conditions are right and the problem not dealt with, the worse it becomes. In my case this problem has occurred since last October with the results I have described.

I hope this gives you some idea of the cause but the detail is very scientific and I'm not at that level of expertise yet !!

Thanks, I'm no scientist but understand what you say. Never heard of this, you learn something new every day.

[mick1211]

Good advice from all quarters

In answer to the good advice from Paul H, Drifter and Alcaucin. My tank is relatively small at 130 litres so major modifications seem a bit over the top.

Nevertheless, I have been looking at fitting a small scale fuel polishing pump which is independent of the engine, to circulate and filter fuel back to the tank before it joins the main injection system. This would ensure that the fuel was always in as good a condition as possible.

I currently have a Racor, first stage centrifugal water and particulate filter, which is where the problem first manifested itself and the filters in the photograph are from this unit.
The black liquid at the bottom of this glass unit is the contaminated water that has been separated from the fuel prior to going towards the engine and the main fuel filter.
This appears to have done its job well as fuel in the main filter was crystal clear and following testing with an agar bacterial test strip, it shows no sign of the bug.

What is bemusing about the whole episode is that with the number of boats of a similar kind in the north east that it is not more of a prevalent problem. Was I just unlucky or did my complacency in not giving more attention to preventative measures, ensure that I was destined to suffer the consequences.

I have learned a valuable lesson and will never underestimate the potential for fuel problems again. I buy my fuel from various sources but never under the counter and always from well used pumps, which I thought was my first safeguard but apparently not so.
Thanks for the help and advice so far................Mick

[alcaucin]

just out of interest, could the position of the tank be a contributing factor i.e is it subject to higher temps by being in a sunny position etc.. just a thought or maybe the centrifuge is warming the fuel in the tank enough to start them off

[Kev1n]

Hi Mick, that’s a cracking boat and obviously well looked after.
You offer some good advice and warnings to beware of diesel bug growth. I’m cautious about it too and add a dose of Marine 16 to the tank at every fill (and a dose of two-stroke oil for lubricity). M16 has a good reputation as being one of the more effective bug controls. I add a slightly higher dose at the end of the season and leave the tank brimmed full to minimise the exposed surfaces where condensation can form. Most skippers also carry spare filters with them and know how to change them even at sea – just in case.

White smoke at start-up can be a warning that the engine isn’t well, usually it is a mist of unburned diesel that quickly clears as the engine warms up and burns properly. Blocked filters will reduce the fuel flow and so limit the maximum engine rev’s but I’m not sure how it would lead to white smoke. Perhaps something to keep an eye on and check the glowplugs are working.

Personally, I prefer to give the boat a run and avoid lots of idling and cold starts which risks causing bore glazing and excessive wear. It keeps the weed growth down and is a good excuse to go out too.

[on the mark]

only ever heard people mention the diesel bug in the latter years so i am wondering why, had diesel engine boats for 28 years and never seen anything like that, bought fuel from various places and had steel and stainless tanks, i used to empty the water trap and change the two filters on the engine on a regular basis and never ever used any preventative as it was unheard of, never seen any other boat suffer from this neither so as i say wondering why now?

[Kev1n]

Good question. Diesel formulations seems to be changing with the drive for cleaner, lower sulphur and more bio-fuel added. The bugs grow in water and bio-diesel is made by a process that generates water so perhaps some of that water is getting into the fuel. Certainly, bio-diesel is often blamed on the increase in bug growth.

[alcaucin]

found this interesting read
Diesel Bug (Bacteria Contamination of Diesel)

Bacteria in diesel is a well known problem to anyone who works with diesel engines, so what is this bug and why does it contaminate diesel?
Diesel is an organic fuel so it provides an ideal environment for microscopic fungi, yeast and bacteria to feed and grow.



This environment provides:
•dissolved water for germination
•carbon for food
•oxygen and sulphur for respiration
•trace elements for growth and propagation.

As many as twenty seven (27) varieties of bacteria are responsible for the majority of problems with diesel engines and their performance. There are many differing types of bacteria which can infect systems and form bio-films on steel surfaces. Accelerated corrosion can also occur wherever the bio-film settles, usually in pits or crevices. Unlike general corrosion, it is an attack on a very specific area.

It is very difficult to determine when a system is first contaminated, but once contaminated diesel enters the fuel system, it is very difficult to eradicate.

Diesel bug can originate from the air or moisture, or during tank filling and/or expansion and contraction of storage tanks, the bacteria cover themselves in a protective film (slime) to protect against biocides and can lie dormant in the minute crevices of the metal, rubber and polyurethane coatings of the fuel tanks and fuel systems.

Then, when water is present (a droplet is a lake to a microbe) and the environment hits the right temperature range, they begin reproduction in the area of fuel/water interface.

Microscopic in size, they can develop into a mat easily visible to the naked eye very rapidly. A single cell, weighing only one millionth of a gram can grow to a biomass of 10 kilograms in just 12 hours, resulting in a biomass several centimetres thick across the fuel/water interface.

Each species has its own characteristics:

BACTERIA
Bacteria utilise hydrocarbons and reproduce asexually by binary fission; swelling in size as they feed, they then separate into two cells. In this way, microbes double their numbers every 20 minutes, one spore converting to 262,144 in 6 hours.

SULPHATE REDUCING BACTERIA (SRB)
SRB's are a specific group of bacteria utilising simple carbon, not hydrocarbons, and require the activity of other microbes in a consortium. Aerobic (in the presence of oxygen) or anaerobic (without oxygen) bacteria have a combined effect. The aerobic bacteria (sulphate oxidising) create a film to consume the oxygen first. This allows the anaerobic (sulphate reducing) bacteria to thrive.

SRB's reduce sulphates and produce hydrogen sulphide (a lethal gas). They are directly involved with many microbial corrosion reactions and can cause sulphide souring of stored distillate products. Their action changes the Ph creating an acidic environment, conducive to accelerated corrosion. They attach themselves to the steel as a film and go to work. They derive their nutrition from the surrounding environment and multiply. They are particularly difficult to deal with and produce a sludgy by-product with a strong sulphur odour similar to rotten eggs (hydrogen sulphide).

IRON REDUCING BACTERIA
These also contribute to corrosion, eating steel and reducing ferrite to an oxide through a chemical reaction.

YEASTS
Yeasts prefer acidic environments, such as produced by SRB's. They bud on the parent cell, eventually separating. Reproduction takes several hours.

FUNGUS
Fungi grow in the form of branched hyphae, a few microns in diameter, forming thick, tough, intertwined mycelia mats at fuel/water interfaces.

All of these can and do cause damage to the fuel system.

PREVENTION
Maintain the fuel system by draining water very regularly, keep the tank as full as possible, (especially over-night) and try to ensure your supplier maintains his system well.

CURE
Clean the entire system with a cleaning agent available from or recommend by your diesel supplier

[alcaucin]

there is some good reading on this subject, one point is that "good housekeeping " alone is not enough. Because of the use of biodiesel and ulsd,
it is necessary to use treatments and probably testing the system more frequently seems the only answer and maybe a continuity of supplier and Perhaps testing the fuel before you put it in the tank may be wise .

[Paul_h]

there is some good reading on this subject, one point is that "good housekeeping " alone is not enough. Because of the use of biodiesel and ulsd,
it is necessary to use treatments and probably testing the system more frequently seems the only answer and maybe a continuity of supplier and Perhaps testing the fuel before you put it in the tank may be wise .

Alcaucin
i have to dis agree with "it is necessary to use treatments" i have never used it and have the 2 off engine filters to polish the fuel with a on-engine filter.

Why, i prefer to manage my fuel this way and my understanding are along the lines of:

The bug lives on the water between that and the diesel, if you treat it and kill it, the gunge sinks to the base of the tank. when cruising around the gunge gets agitated and suspended in the fuel which is then pumped through your fuel system, hitting the fuel lines, filters and injectors and recirculated on the return back into the tanks. if you have a single filter then there is less gunge getting captured then the filter clogs and the engine starts hiccuping.

i prefer to, don't kill it, set a pre-filter system up with premium (Fleetguard) course, fine and finer micron filters. drain any water off on a regular basis from the filter drains. either fit a vacuum gauge or change the filters at regular intervals.

The vacuum gauge takes the guess work out of it and prevents premature changing of filters. when the gauge is reading 8-10 Hg the i look at changing filters, if i would to leave them longer say 16-18 on the gauge, then the pump suction is being starved and fuel is restricted getting to the injectors.
like sucking through a straw, then nip the end and try and suck.
I find that i change 1st filter 3 times and second filter twice and the on engine once, on a filter change cycle.

even then there are times when i rip the fleetguards open to look, the 2nd filter and on engine are still clean. there are also times that you can see some build up in the second, but the on-engine is always clean.
i use a lot of fuel when i'm home, it stands weeks while away at graft, but the tanks are kept full to reduce the condensation.

These are my thoughts and how i do it, not saying it is right or wrong, but it works for me, and i'll buy cherry from anywhere. but it is not necessary for me to go down the lines of a chemical treatment.

i am keeping a log of filter date changes and hours, so i can get a feel of how much fuel is getting burnt during this filter change cycle, IF i remember to log how much fuel is going in the tank, sometimes i forget to log it.
Not that it matters just or info and reference, the vacuum gauge is the warning that the filter is getting blocked, that's what they are designed for.

hope it helps


incoming !!!..............
tin hat and flak jacket is on

Paul