Diesel bug

[rogerthebodger]

Is it possible to get diesel bug in you tank without water in the bottom of the tank ?

Also must the water in the diesel tank be fresh water or can it be sea water ?

 

[Topcat47]

The bug lives in the interspace between oil and water. Therefore there must be some water for it to thrive. Salt or fresh doesn't seem to make much difference, I've had the bug with rainwater and salt in my tank. I always use biocide when toping up nowadays it's not really the water that's the killer but the black crud. I don't like using an emulsifying agent in my fuel.

 

[lw395]

You can get diesel bug when you fill up.
'Diesel Bug' is a catch-all term for a whole variety of microbes, bacteria, funghi etc, not one species of anything, so it can happen with dissolved water, sea water or freshwater in the tank, or possibly in the air space above the fuel.
Most commonly though, I think it's fair to say water at the bottom of the tank, with a large water-fuel surface is the most likely breeding ground.
Like dry rot, these things can create their own water when they get going.

 

[rogerthebodger]

Thks guys

The reason I asked is the I have found some black crud in my tanks but have checked my tank with a water indicating paste often and had no indication at the lowest point in my tanks.

Diesel here is always from a road transport depot so most all have a high turnover of diesel and my tank filler is way above my bridge deck at the same level as the bottom my companionway so very little chance of water getting in the filler. Also the filler has an raised cap not one that is flush with the deck.

I plan to clean out the tank with my fuel polisher and a roving suction pipe to bet in the corners. I will then fit a big strainer before my primary filter to monitor it the crud returns.

 

[Topcat47]

You can easily get condensation in a part full diesel tank and the water will settle on the bottom, eventually. in Europe, it's common to have 5 or even 10% Ethanol (biofuel) in Road Diesel. It's hydroscopic so it can and will attract moisture from the air. If you use a lot of Diesel, it's not a problem. My road vehicle is a Diesel but it uses about 35 litres a week from a 60 litre tank so it's not in the tank long enough for a problem to develop. Were I to use it on my boat, however, 60litres will normally last me over a year and that's why I prefer "red" diesel, which does not as a rule include the bio element.

I once had a tank full of road diesel that was 50% water....my car didn't run on that. It cost me nearly £300 what with recovery to a garage and the work needed to empty the tank, clean the pipes, and run the fuel though the injection system.

 

[pcatterall]

Thks guys

The reason I asked is the I have found some black crud in my tanks but have checked my tank with a water indicating paste often and had no indication at the lowest point in my tanks.

Diesel here is always from a road transport depot so most all have a high turnover of diesel and my tank filler is way above my bridge deck at the same level as the bottom my companionway so very little chance of water getting in the filler. Also the filler has an raised cap not one that is flush with the deck.

I plan to clean out the tank with my fuel polisher and a roving suction pipe to bet in the corners. I will then fit a big strainer before my primary filter to monitor it the crud returns.

Is the black 'crud' soft and slimy or hard and baked on? We suffered the hard baked on stuff. The additives we then used seemed to ' dissolve' the baked on black layer but turned the diesel itself black.
The diesel could neither be filtered ( several futile passes through my 2 micron polisher) nor would it settle out.
We are told that the particles are so fine that they will pass through the engine without adverse effect!

 

[CAPTAIN FANTASTIC]

Is the black 'crud' soft and slimy or hard and baked on? We suffered the hard baked on stuff. The additives we then used seemed to ' dissolve' the baked on black layer but turned the diesel itself black.
The diesel could neither be filtered ( several futile passes through my 2 micron polisher) nor would it settle out.
We are told that the particles are so fine that they will pass through the engine without adverse effect!

The black "crud" is soft like tar and it blocks filters. Has happened twice in our LandRover car during very low temperatures. Every winter, on the boat, I syphon the bottom of the tank to make sure i don't have water accumulating and any black tar.

 

[yerffoeg]

Captain Fantastic , I like your idea of siphoning the tank in the winter, something I have never done. How do you go about it?

 

[[70521]]

You can easily get condensation in a part full diesel tank and the water will settle on the bottom, eventually. in Europe, it's common to have 5 or even 10% Ethanol (biofuel) in Road Diesel. It's hydroscopic so it can and will attract moisture from the air. If you use a lot of Diesel, it's not a problem. My road vehicle is a Diesel but it uses about 35 litres a week from a 60 litre tank so it's not in the tank long enough for a problem to develop. Were I to use it on my boat, however, 60litres will normally last me over a year and that's why I prefer "red" diesel, which does not as a rule include the bio element.

Do you have any evidence to support that statement about red diesel?

 

[[70521]]

Captain Fantastic , I like your idea of siphoning the tank in the winter, something I have never done. How do you go about it?

Tongue in cheek, with a very long pipe.

 

[CAPTAIN FANTASTIC]

Captain Fantastic , I like your idea of siphoning the tank in the winter, something I have never done. How do you go about it?

Its easy to syphon when the boat is out of the water, using a small diameter long pipe , one end into a container on the ground and the other end inside the tank, moving it around. You will be amaged how much dirt is inside the tank; takes no more than 15 minutes and a container with approx 4 litres of dirtyish diesel.

 

[lw395]

Its easy to syphon when the boat is out of the water, using a small diameter long pipe , one end into a container on the ground and the other end inside the tank, moving it around. You will be amaged how much dirt is inside the tank; takes no more than 15 minutes and a container with approx 4 litres of dirtyish diesel.

I use a pela oil extractor for this. You'll need a bigger bore tube than the supplied bowdencable outer.

 

[[70521]]

Its easy to syphon when the boat is out of the water, using a small diameter long pipe , one end into a container on the ground and the other end inside the tank, moving it around. You will be amaged how much dirt is inside the tank; takes no more than 15 minutes and a container with approx 4 litres of dirtyish diesel.

I have a maintenance schedule that includes removing and cleaning the tank every three years, OK the tank is simple to remove and this might not be possible for some boats, and am always amazed at the amount of crud that gets into a tank.

If your primary filter is below the bottom of your tank you can also remove the fuel from this end.

 

[lw395]

Is the black 'crud' soft and slimy or hard and baked on? We suffered the hard baked on stuff. The additives we then used seemed to ' dissolve' the baked on black layer but turned the diesel itself black.
The diesel could neither be filtered ( several futile passes through my 2 micron polisher) nor would it settle out.
We are told that the particles are so fine that they will pass through the engine without adverse effect!

There are two distinct problems AIUI.
Bug is biological slime, assorted.
Asphaltene and other 'tarry black shit' is a breakdown product of the fuel, a process which can be catalysed by yellow metal. E.g. copper fuel pipes, brass fittings etc. Some of the tarry byproducts are actually soluble in alcohol and/or various stuff that's in additives and biocides.

Some additives may make it hard to tell one from the other, as they tend to break down the bioslime and dissolve the tar turning the diesel into a grey mess.

 

[pvb]

Its easy to syphon when the boat is out of the water, using a small diameter long pipe , one end into a container on the ground and the other end inside the tank, moving it around. You will be amaged how much dirt is inside the tank; takes no more than 15 minutes and a container with approx 4 litres of dirtyish diesel.

I also remove water/crud from the bottom of my tank every winter. But I do it afloat, using a narrow rigid plastic tube to go in to the tank, and a flexible tube with an outboard primer bulb in it, and just pump a few litres of fuel in to a container.

 

[thinwater]

Is it possible to get diesel bug in you tank without water in the bottom of the tank ?

Also must the water in the diesel tank be fresh water or can it be sea water ?

Yes, you absolutely can (many years in the refining industry). It can grow in pipelines where there is constant movement, so long as the flow is moderate. What is required is emulsified (dispersed) water, but 100 ppm is enough.

Polishing will help, but it won't remove the attached sludge and it won't remove small colonies living in the pipes and filter housing. You need to mechanically clean the tank and treat now (shock) and continuously (maintenance) for at least a while with a biocide, such as Biobor JF.

I've been through this many times, on scales ranging from <100 gallons to >10,000,000 gallons. Take shortcuts and at just comes back. For me, the piece of mind of doing it right is worthwhile. It really sucks when everything plugs up at the worst time.

 

[NormanS]

Good fuel tanks are fitted with a small dirt sump with a drain. Any movement of the vessel encourages any water or dirt to gravitate into the sump, from where it can be periodically drained. Job done.

 

[rogerthebodger]

Thanks again Guys

My tanks are steel welded into the steel hull so cannot be removed but I do have big top hatches that can be removed to gain access to the inside around the baffles.

The crud id soft black and I am in the process of pumping out from the bottom of the tank using a pipe probe so I can get into the lower corners. The pump I have been using id a jabsco gear pump with a mesh strained that catches to crud.

Once I had got out all I can that that pump I will use my transfer pump that passes through a strainer and my primary CAV filter.

Each of my tanks are about 650 litres each and one is full and the other is 3/4 full so cannot really remove all the diesel and remove the crud by hand.

Any advice on treatment considering the size and that there is no water in the tanks.

Due to the shape of the tank/hull the crud does tend to accumulate at the lowest point that is a drain point.

 

[dom]

Oh dear :ambivalence:. My tuppence worth:

1. Phone around and see if you can find a lab which can give you a definitive on what's up with your fuel; i.e. asphaltene, bug, or whatever. As a matter of interest, do you have common rail engines as the high pressure/temp these work at can scorch the fuel causing asphaltenes?

2. Keep doing what you're doing until you've got about as much of the crud and water out as you can and safely dispose.

3. If bug, treat to shock level with something like Marine 16, or whatever you have in SA. If asphaltene, ask an oilco to advice a suitable asphaltene conditioner. BTW if bugs, treatment must be a biocide, not an enzyme treatment alone.

4. Construct a polishing contraption: basically a 12/24V diesel pump, pressure gauge and two filters in series: say 30 and 10 Micron filters. Use something like a Racor if poss where you can buy cheap knock-off Chinese cartridges (you'll need loads!) and where the filters are easy to examine and change. Buy a decent diesel pump capable of running the system up to close to the maximum working pressure/throughput of your filters. Then just work away, occasionally stirring the contents of the tank if possible and moving the suction pipe around to hoover up what you can. You might need to ultimately go down to 2 Micron if asphaltenes.

5. Watch your tanks like a hawk for a year or so, dipping regularly, and keeping a maintenance level of appropriate fuel conditioning treatment. Regularly dip tanks and be ready to knock any bug regrowth on the head with a shock retreat!

 

[pcatterall]

There are two distinct problems AIUI.
Bug is biological slime, assorted.
Asphaltene and other 'tarry black shit' is a breakdown product of the fuel, a process which can be catalysed by yellow metal. E.g. copper fuel pipes, brass fittings etc. Some of the tarry byproducts are actually soluble in alcohol and/or various stuff that's in additives and biocides.

Some additives may make it hard to tell one from the other, as they tend to break down the bioslime and dissolve the tar turning the diesel into a grey mess.

Yellow metal !! ??…. sounds like my brass dip pipes ( which are permanently in the tanks ) could be having an effect though this has only been noted in the last 3 years.