Filtering grey diesel. initial trial.

[pcatterall]

If you've already passed the fuel several times through your polishing kit, there'll be nothing left which would cause a problem to your engine. So just get on and use it!

Thanks pvb, that's a confidence builder! . I had a concern that the particles might become 'tarry' again with engine heat and might be deposited on the inside, perhaps building up around the injectors.

Perhaps 'friendly pub landlords' is the myth? I do recall that an alleged trick was to wring out the filter pads to get the last few drops back into the barrel!

 

[Hydrozoan]

In fuel filter testing most specs use lab filter membranes to check efficiency .these are 0.45 micron made by a company called Sartorius

but you will need vacuum assistance to pull a sample through the membrane.

Whatman are the filter specialists. Readily available on eBay

Many companies make or sell 0.45um membrane filters – that nominal pore size has become a very widely-used de facto standard for separating so-called ‘dissolved’ and ‘particulate’ fractions. At least some are nylon and some cellulose based – but the OP would need to check the compatibility of any specific make/type with diesel – and as you say, he’d need a suitable filter holder (the most common laboratory filter diameter is 47mm) and a Buchner flask and vacuum source; with heavy particulate loadings they do tend to clog (as would many filters at such fine sizes). Glass fibre filters are also available down towards that pore size IIRC; they have less specific size cut-offs but tolerate higher particulate loadings.

 

[pcatterall]

I see that I can get a 5 micron filter from asap which will fit my CAV unit. I will try these in the polisher and see if they have any effect. If a few passes with these fine filters don't work then perhaps I will assume that the particles pose no problems.
Thanks all

 

[chrishscorp]

I would suggest filtering it through a finer filter, 8 microns seems quite large. A chum ran his car on used veg oil for 15 years and he strained it down to 2 microns fairly easily.

 

[pcatterall]

I would suggest filtering it through a finer filter, 8 microns seems quite large. A chum ran his car on used veg oil for 15 years and he strained it down to 2 microns fairly easily.

I would like to find 2micron filters to fit my CAV unit as installed in my fuel polisher. I have located 5 micron at ASAP ( only £2.50 each as well) and will try these.
I don't really want to change the filter unit body for one of the more expensive units especially when I see the price of the actual replacement filters.
While 10 micron seems coarse this has been a standard for older diesels for years, more modern engines call for finer filters.
I recall also that progressively more particles are retained with each pass through a filter, this is usually evident with my system as dirty looking diesel looks clearer/brighter
with each pass ( up to 4 or 5 when little improvement in clarity occurs)

 

[Muddy32]

Urban myth!
Stu

I find that I can filter the beer quite well, my kidneys work ok.

 

[Gunfleet]

Dunno about wax or water, but fuller's earth (aka cat litter) is notorious in Ireland as a substance which will remove foreign substances from diesel.

 

[chrishscorp]

My chum I am sure use to use a bag type filter you could get several litres in at a time, they use to flog them on a well know auction site but i cannot find any on there now. If you have someone in the area making biofuel and selling it, it would be worth asking them as many filter it down to 1 or 2 microns.

 

[pcatterall]

This below from Peter at Marine 16 concerning the grey discolouration of my diesel that niether repeated filtering nor long standing would seperate out....... Its not down to water in tank...
I suggested that I try to filter with a very fine filter ( 2micron) and if that does nothing then I will just use the fuel ( but I will give the tank another clean)
　
As the deposits are “tarry” then I would suspect it maybe asphaltenes. Asphaltenes are becoming a much greater problem. Particularly where fuel is mixed from various supplier/ countries as in the Med.
They form when mainly different fuels are mixed but also in degraded fuel that is subjected to the heat and pressure when cooling the engine and returning to the tank many times.
However as you have had the problem, filled with new fuel (I assume from one supplier) the problem is an interesting one.
As you are using road fuel then this will be EN590 with a biodiesel content. Biodiesel degrades very rapidly, often in less than 6 months. By the time the end user gets it it could already be over 2 months old.
I would agree putting it through a 2 micron filter.
How long was it before the fuel turned grey again?
　
　My response
I propose to put my questions and your answers onto the Practical Boat Owner Forum if that is ok with you.
Fuel is always a 'hot' topic there and many users will be interested in your responses.

Although there HAD been a tarry deposit ( seen mainly on my brass dipstick, but only recently) this seemed to disappear ( possibly after adding your bug treatment)
as the deposit disappeared the grey looking diesel appeared!
I think that the grey look reappeared some 4 to 8 weeks after adding around 20 L of new fuel to the 5 L left at the bottom of the tank. since then around 150L has been added from different sources and it is all now grey.
The Perkins engine does seem to return a lot of fuel to the tank. I guess that the engine has only done 30 hours ( around 70 L) but possibly a lot more fuel than that has done at least one pass through the injector pump.
I will continue my testing and will try one of those testing kits on the grey stuff.

 

[lw395]

AIUI, Marine 16 is designed to break down 'diesel bug' and disperse it in the fuel.
This would appear to have happened.

There are two main ways of dealing with bug, either filter it out or reduce it to something that will go through the injectors.
Once you've chosen the latter option, there may be no going back.
If it's 'pure' asphaltene, or other 'tarryblackshit', I'd expect it to dissolve in the diesel if the treatment acts as a solvent. So the fuel would become tinted but not cloudy?
If it's cloudy, that suggests some sort of micro-emulsion.
Could there have been other stuff than the tar lurking in the bottom of the tank?

There would seem to be 3 options:
1) accept the treatment has done the job and the grey will go through the engine without harm.
2) get rid of the grey diesel and clean the system.
3) look for chemical approaches to remove the contamination

Chemically removing any water which is present might be an approach?
AIUI, various salts are used for this. But DYOR and try it on a small sample, don't blame me etc.

Also the 'old way' was AIUI, to chuck some methanol in, which dissolves in both water and diesel, reducing everything to a solution.

 

[pcatterall]

Thanks lw395
Not certain if it is cloudy or tinted my guess would be tinted, the tank should have been fairly clean. I am beginning to accept your suggestion 1 but I will also try polishing again with my 'new 5micron' filters and even try testing with 2micron if I can find ( FINE) lab filter papers or filter bags in small ( economic ) quantities.