Black diesel ......part 3

[jdc]

The OP needs to google what shell says about copper and zinc in contact with bio diesel.

+1.

I've been saying for years on this forum that ULSD is much less stable than the good old high-sulphur distillate stuff, and yet the snake-oil industry always try to blame any instability issues on microbial growth, aka 'diesel bug'. That exists, but is by no means the only, and is probably the rarer, cause of black deposits. Lots on Shell, Chevron, BP, US government etc etc. The most authoritative source is probably US Standard ASM D975: Specification for Diesel Fuel Oils, which states "Copper and Copper containing alloys should be avoided. Copper can promote fuel degradation and may produce Mercaptide gels..."

No copper piping has been used on cars for years (admittedly this is as much to do with mechanical as chemical properties); how long until boat builders catch up? 30 years behind the curve is about right, so we're half way there...

 

[pcatterall]

Good custard should have some air in it, much lower bulk modulus than diesel.
We have digressed.
The OP needs to google what shell says about copper and zinc in contact with bio diesel.

Absolutely! With the evidence available I am working on the assumption that it is the marine 16 additive that has removed the deposited tar from the tank sides and discoloured the fuel in doing so. I have just polished the whole tank twice with the 5 micron filter and there has been no change in the black colour nor any gunge or water in the filter. I now propose to use the fuel as it is!! Touching wood!!!

 

[KellysEye]

>The point you're missing is that in practical everyday matters, all liquids (water, oil, custard etc) are virtually incompressible.

So I'm mainly right then.

 

[Deleted member 36384]

Absolutely! With the evidence available I am working on the assumption that it is the marine 16 additive that has removed the deposited tar from the tank sides and discoloured the fuel in doing so. I have just polished the whole tank twice with the 5 micron filter and there has been no change in the black colour nor any gunge or water in the filter. I now propose to use the fuel as it is!! Touching wood!!!

Do you have copper fuel pipes from tank to engine, return lines, filtering (polishing) pipework? It would be interesting to know as so far, the only source mentioned is modern road fuels, which you state you are using and copper / copper alloy metal.

 

[RichardS]

>The point you're missing is that in practical everyday matters, all liquids (water, oil, custard etc) are virtually incompressible.

So I'm mainly right then.

"Mainly right" or "totally wrong"?

It's a close call.

Richard

 

[vyv_cox]

>The point you're missing is that in practical everyday matters, all liquids (water, oil, custard etc) are virtually incompressible.

So I'm mainly right then.

Perhaps you can explain why you think that any change in the compressibility of any liquids being pumped could be responsible for destroying the injectors? As others have said, there are many other possible causes, such as lubricity and corrosion, but I am struggling to understand where compressibility enters into it. We all know that pumping air through injectors does not destroy them, so why should a liquid other than diesel fuel?

 

[macd]

So I'm mainly right then.

Wrong again. My, you do have a talent for this.

 

[pcatterall]

Do you have copper fuel pipes from tank to engine, return lines, filtering (polishing) pipework? It would be interesting to know as so far, the only source mentioned is modern road fuels, which you state you are using and copper / copper alloy metal.

Interesting....in fact I do have a mix of copper and plastic though the polisher is all plastic. The black occured over a period of storage in the GRP tank rather than usage through the engine so my current bet is on the additive but I will keep the copper possibility in mind and replace eventually. The good stuff in the port tank has been polished and remains clear.

 

[Deleted member 36384]

Interesting....in fact I do have a mix of copper and plastic though the polisher is all plastic. The black occured over a period of storage in the GRP tank rather than usage through the engine so my current bet is on the additive but I will keep the copper possibility in mind and replace eventually. The good stuff in the port tank has been polished and remains clear.

The reason I asked is that I too have GRP tanks and have had them cleaned (I decommissioned one because I simply do not need that volume of fuel) They contained black fines which was quite hard and it was all washed off with some product (I got a contractor to do it). About 10 years ago new fuel pipes were fitted which were all soft lines except for a short length of copper between the pump and filters. So far, so good but I use marine diesel.

 

[<152587>]

Bit of interesting reading herehttp://www.mycleandiesel.com/pages/ProblemWater.aspx

 

[Trundlebug]

Thanks for this.
I appreciate that moisture in the fuel can be a big issue but ,perhaps, not the problem here. While removing water held in the fuel (which won't just separate out) is important I don't see that particle size is irrelevant.
Going to try the 5micron filters now.

I see your point but moisture is the biggest cause for concern, not appearance, some interesting info here
http://cumminsfiltration-empty.bitn...iles/FleetFacts - Fuel Systems - Mar 2014.pdf

 

[Boo2]

Thanks all. My assumption is that the marine 16 additive has done what it said on the can by removing the tar causing element and converting it to what are hopefully harmless suspended particles.
It is correct that the only other difference between the two tanks is that one receives returned fuel but the engine works fine and the discolouration occured mainly while standing unused rather than in use.

Try dosing the other tank with the Marine 16 additive - if that fuel also goes black then you will know the cause is not the engine...

Boo2

 

[pcatterall]

Try dosing the other tank with the Marine 16 additive - if that fuel also goes black then you will know the cause is not the engine...

Boo2

No thanks !! That tank is staying unadulterated for now! I don't want to proove a theory but finish up with even more suspect fuel! But.......on reflection.... I could change dipsticks around or test just the tarry one in a bottle of the black fuel.