Black/dirty diesel

[Squeaky]

Good morning:

A neighbor had to remove his fuel tank (plastic or some such material) yesterday so pumped out the diesel into 10 litre bottles and discovered that it was black instead of the normal light brown colour.

He was advised to let it settle for a week or so in hopes that the foreign material would settle to the bottom however has decided to replace it with fresh diesel when re-filling the tank.

This diesel was purchased last year and has sat undisturbed over the winter months and no known source of contamination has been discovered.

The first question is "what the heck could have caused the diesel to turn black?"

The second question is "would the diesel be usable without causing any harm to the engine?"

Cheers

Squeaky

 

[cryan]

Micro biological contamination or Diesel Bug can cause the formation of a coal dust looking substance in the fuel, especially in filters and will discolour fuel black. That same substance if it gets through the filtration can cause terminal damage to fine tolerance components such as fuel injectors and injection pumps.

 

[NUTMEG]

That same substance if it gets through the filtration can cause terminal damage to fine tolerance components such as fuel injectors and injection pumps.

Really? Bit scaremongery isn't it? I fail to see how a slime mould can damage a hardened steel injector nozzle. Would love to learn more.

 

[Topcat47]

My own experience of the diesel bug suggests the black sludge that collects in the bottom of the tank clogs the filters. I've never had the stuff get to the fine fuel filter, but the bugs themselves are microscopic and the contamination spreads throughout the whole fuel system unless flushed through thoroughly. You don't have to replace all the lines, but after steam cleaning the tank (easy to organise once it's out) it can be re-filled with fresh diesel, which can then be treated with a biocide. Bleeding this through the system is usually enough to knock the residual bugs on the head.

It's possible to "polish" the contaminated diesel and re-use it. Indeed there are companies out there who will come and do it for you, but it's not usually economic for small quantities, even on a DIY basis. Disposal of the diesel is another matter entirely.

 

[KellysEye]

I'm not aware that slime can damage injectors but I do remember a boat in Trinidad that filled it's tank and it turned out dock tank was nearly empty and it pumped 90% water which destroyed the injectors. Water is the only thing that can't be compressed hence the damage.

 

[cryan]

Really? Bit scaremongery isn't it? I fail to see how a slime mould can damage a hardened steel injector nozzle. Would love to learn more.

Well because it's not just slime. It's micro organisms that die and form carbon like deposits that are hard enough to damage steel. Especially in components such as injectors and injection pumps where the tolerances are measured in microns. This is compounded by the slimy part that blocks fuel lines and injector nozzles.
But hey, feel free to ignore my advice but I guarantee that a tank of clean fuel and a dose of biocide is cheaper than a set of injectors, filters and a fuel pump.

Paragraph 1: http://www.kleenoileurope.com/?p=diesel_bug

 

[pvb]

Water is the only thing that can't be compressed hence the damage.

I never realised diesel fuel could be compressed.

 

[RichardS]

I'm not aware that slime can damage injectors but I do remember a boat in Trinidad that filled it's tank and it turned out dock tank was nearly empty and it pumped 90% water which destroyed the injectors. Water is the only thing that can't be compressed hence the damage.

Not quite. No fluids are compressible which includes diesel and petrol as well as water. Gases are compressible.

Richard

Slow!

 

[NUTMEG]

Well because it's not just slime. It's micro organisms that die and form carbon like deposits that are hard enough to damage steel. Especially in components such as injectors and injection pumps where the tolerances are measured in microns. This is compounded by the slimy part that blocks fuel lines and injector nozzles.
But hey, feel free to ignore my advice but I guarantee that a tank of clean fuel and a dose of biocide is cheaper than a set of injectors, filters and a fuel pump.

Paragraph 1: http://www.kleenoileurope.com/?p=diesel_bug

Thanks for the link, still fail to see how injector damage can occur. Oxidisation from water yes, damage from mould, no. Blocked filters are bad enough, without egging the pudding with injector damage.

I did not wish to offend.

 

[Topcat47]

Injectors have small clearances between moving parts that are lubricated by the diesel. Water washes the Lubrication from the parts and they start to wear. As the clearances are so small, this wear considerably shortens their working life.

 

[lw395]

Thanks for the link, still fail to see how injector damage can occur. Oxidisation from water yes, damage from mould, no. Blocked filters are bad enough, without egging the pudding with injector damage.

I did not wish to offend.

I think the slime may be acidic or otherwise prone to react will the expensive metal bits.

 

[lw395]

Not quite. No fluids are compressible which includes diesel and petrol as well as water. Gases are compressible.

Richard

Slow!

not quite exactly.
Water compresses, just not very much!

 

[sarabande]

of the many different species of bugs which can live in diesel, many are capable of altering the pH (acidity) of the diesel during the contamination process. Add this to diminution of the lubricity of clean fuel, and the rather high pressures (around 15000 psi) of the injector/common rail system, then a very finely machined injector really doesn't stand much chance of avoiding damage.

 

[KellysEye]

>I never realised diesel fuel could be compressed.

Yes it can as can petrol, wood, steel, tungsten, carbon and every other substance on the planet except water.

>No fluids are compressible which includes diesel and petrol as well as water.

If that were the case why does water destroy injectors but not diesel.

 

[NormanS]

Not quite. No fluids are compressible which includes diesel and petrol as well as water. Gases are compressible.

Richard

Slow!

"Fluids" include gases.

 

[pvb]

>I never realised diesel fuel could be compressed.

Yes it can as can petrol, wood, steel, tungsten, carbon and every other substance on the planet except water.

It's a common misunderstanding, but if you check your facts, you'll find that water is compressible, just not very much. But other liquids are even less compressible - glycerine, for example.

 

[RichardS]

"Fluids" include gases.

Yes.... but hardly germane to a discussion about water and diesel.

And neither is the fact that water is minutely compressible, as, in the ultimate, is all matter since the entire mass of the universe started off about the size of a football..... But is that relevant?

Richard

 

[RichardS]

Lubricity.

Richard

 

[paddywackcocker]

The bug as I understand it lives and grows in the interface between diesel and water.
Bug treatment usually does two jobs, kills the bug (hopefully) and then breaks down the film in between allowing it to be suspended in the diesel and removed by filtration and moisture separation.
The hole breeding bit is like a giant Petri dish, little bit of moisture, bit of old diesel, fuel tank usually located near engine and then a nice flow of warm diesel being returned to the tank just toget them in the mood and up and running, close up the boat walk away for a few weeks and hey there having a party.
I've got a fully baffled tank and you can only access one compartment. I've installed a switch over manifold and twin filters.
3 tank fulls later and 6 filters, 5 full on pipe blockages (10 to 8mm) in pick up pipe to delivery pipe, the water collection bowls are looking purity good and the fuel is going the nice clear ruby colour.
The damage caused to injection system can be the moisture suspended in the fuel when left over a long period can cause damage to the fine tolerances in the pump/injectors by creating minute rust Pitts. To much water and thats curtains, if the injection pump managed to pump it and the injectors managed to inject it (I've never known this) but the atomised water would stop engine if not it would bend the connecting rod.

 

[NormanS]

The bug as I understand it lives and grows in the interface between diesel and water.
Bug treatment usually does two jobs, kills the bug (hopefully) and then breaks down the film in between allowing it to be suspended in the diesel and removed by filtration and moisture separation.
The hole breeding bit is like a giant Petri dish, little bit of moisture, bit of old diesel, fuel tank usually located near engine and then a nice flow of warm diesel being returned to the tank just toget them in the mood and up and running, close up the boat walk away for a few weeks and hey there having a party.
I've got a fully baffled tank and you can only access one compartment. I've installed a switch over manifold and twin filters.
3 tank fulls later and 6 filters, 5 full on pipe blockages (10 to 8mm) in pick up pipe to delivery pipe, the water collection bowls are looking purity good and the fuel is going the nice clear ruby colour.
The damage caused to injection system can be the moisture suspended in the fuel when left over a long period can cause damage to the fine tolerances in the pump/injectors by creating minute rust Pitts. To much water and thats curtains, if the injection pump managed to pump it and the injectors managed to inject it (I've never known this) but the atomised water would stop engine if not it would bend the connecting rod.

All the more reason for having water traps with drains, on the bottom of well designed fuel tanks.