Black diesel ......part 3

P

pcatterall

Well-Known Member
Joined
2 Aug 2004
Messages
5,508
Location
Home East Lancashire boat Spain
Visit site
I posted 2 threads on this but we have moved on a step so I will ask for advice again and possibly the story may inform others.
Story so far.
Neptunian 33' cruiser based in Spain , 2x 50 gallon GRP tanks both cleaned 3 years ago. Starboard tank is the working tank port is just a store with fuel pumped across via the polisher as needed.
We are using road fuel

A year ago I noticed that both dip sticks were getting a hard tar like coating, I assumed that this was also coating the tank sides and was concerned that it would do my injectors and engine no good (Perkins 4108) I use the all purpose addetive from marine 16 but only in the starboard tank 2 months later the fuel had gone black , tried multiple passes through the polisher but no impact and there was no sign of it settling out either, there was no big or water fixable. We dumped most of the contaminated fuel but on refilling it went black within a month.

After several months we have returned ready to resolve the issue and armed with 5 micron filters for the polisher and a test kit from marine 16 .
First check was to examine the dip sticks........the port tanks still had the hard tar coating and the fuel was still clear, the starboard tank stick was clean but the fuel still grey/ black.
I believe that the addetive used in the starboard tank has dissolved the tar which I guess is asphaltin and it is held in fine suspension in the fuel. I have read that the particles are so fine that they will's pass harmlessly' through the engine, this is borne out to some degree by the fact that repeated polishing passes have no effect ( in the past it has cleaned the funniest fuel).
I propose to use the new 5 micron filters in the polisher and even f that doesn't work will use the fuel on the understanding of what I read and also because the recommended filter for my engine is 10 micron so what passes through multiple passes through my 5 micron filter should be fit to use??????
What's the feeling guys???
 
third engines said:
Could you elaborate on this theory please, willing to learn something new every day. Thanks
Click to expand...

It's a question, not a theory. I am trying to explain to myself why the fuel is gong black but not due to growth of bug or presumably due to dissolving something in the tank or hoses. As I understand it the blackening is occurring in the active tank but not the storage one (?). One possible is the return hose from the injectors. If they are not opening and closing at design pressure there would be some blowback.
 
It's probably going black due to copper alloy metals in the fuel plumbing.
Not compatible with modern road diesel.
Some sort of catalytic effect.
 
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.
 
Although you state you're polishing the fuel with 5 micron filters, are they coalescing filters that absorb entrained moisture / water? That's the key factor when polishing fuel, not particle size.

The filters must be of a type that absorb water, not all do.
 
Trundlebug said:
Although you state you're polishing the fuel with 5 micron filters, are they coalescing filters that absorb entrained moisture / water? That's the key factor when polishing fuel, not particle size.

The filters must be of a type that absorb water, not all do.
Click to expand...
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.
 
>The filters must be of a type that absorb water, not all do.

I'm not aware of filters that absorb water, Racor filters catch water and you can see it in the clear bowl under the filter, it has a drain to get it out. In the Caribbean water in diesel fuel is endemic, one boat in Trinidad had it's injectors destroyed by unknowingly filling their tank with 90% water and 10% fuel, water is the only substance that won't compress.
 
KellysEye said:
>The filters must be of a type that absorb water, not all do.

I'm not aware of filters that absorb water, Racor filters catch water and you can see it in the clear bowl under the filter, it has a drain to get it out. In the Caribbean water in diesel fuel is endemic, one boat in Trinidad had it's injectors destroyed by unknowingly filling their tank with 90% water and 10% fuel, water is the only substance that won't compress.
Click to expand...

You might want to rethink that.
 
lw395 said:
You might want to not waste your time.
Click to expand...
Dunno which way you are going but the injector pump will pump any liquid that is fluid enough to pass through it, the injectors will "open" and spray any fluid that has gone through the pump. What that fluid does to the pump and injectors is anybody's guess from the point of view of corrosion and lack of lubrication. The incompressible bit comes in to action when water is sprayed in to the cylinder, eventually because it isn't combusting the amount of water could build up in the cylinder and hydraulicing could occur which I suspect is where Kelly's Eye is coming from?
 
skipper_stu said:
Dunno which way you are going but the injector pump will pump any liquid that is fluid enough to pass through it, the injectors will "open" and spray any fluid that has gone through the pump. What that fluid does to the pump and injectors is anybody's guess from the point of view of corrosion and lack of lubrication. The incompressible bit comes in to action when water is sprayed in to the cylinder, eventually because it isn't combusting the amount of water could build up in the cylinder and hydraulicing could occur which I suspect is where Kelly's Eye is coming from?
Click to expand...

I don't see how that can explain Kelly's Eye totally incorrect statement that "water is the only substance that won't compress". Even "water is the only liquid that won't compress" would be nonsensical. :confused:

Richard
 
macd said:
No-one suggested water compressed "a lot". The point you're missing is that in practical everyday matters, all liquids (water, oil, custard etc) are virtually incompressible.
Click to expand...

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.
 
You must log in or register to reply here.

Share this page

Top