Diesel sludge - here to stay?

guydickinson

guydickinson

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Last year I had to clean out the tank (the marine engineer who was fixing the fuel system suggested it). It was full of black sludge - presumed the bacterial sort. The tank was thoroughly cleaned. New diesel put in as well as a good dose of anti bug additive (forget which now but think its american). This year the tank had to be emptied again (this time a faulty guage). To my horror, the sludge has returned. Any suggestions please about what else one can do?!! Also have I got to dump the 60 odd litres of diesel? (the last bit was decanted separately in case of sludge in it - the other lot looks clean). No evidence of any water by the way.
 
Your local marine engineer might have a fuel scrubber.

Also, I understand that the bug breeds at the water/fuel interface, so keep your tank topped up to reduce condensation, and drain off water from the bottom.
 
Time to change suppliers .. I tend to take a 25l plastic carrier down .. Just use ordinary deisel from service station .. At least you know its fresh and not been stored for months .. Perhaps the supplier needs to put diesel bug killer in his tank .. Can you imagine what the bottom of his tank must be like .. /forums/images/graemlins/frown.gif
 
As ex_finn_sailor says, chances are that the fuel you bought was already contaminated. Many marine fuel bunkers are supplied by barge, they may have been carrying water, drilling mud, in ballast with seawater, etc. before they carried your fuel.

No reason why you should discard the fuel you have. Once the sludge has been removed the fuel will be perfectly OK, although a dose of Soltron won't do it any harm.
 
I've just cleaned my tank, after taking out 800 litres. The opinion from the diesel engineer and many others is that fuel is not as good as it was fifteen years ago, full of tars and other contaminants. Certainly I had to scrape the inside to get the sludge off, I don't think it's the bug, doesn't look like it, and I treat all the incoming fuel. Since it was stuck to the tank walls it won't get down to the sump. Is there a good treatment to get rid of the muck?
 
While we're on fuel problems. When we bought our boat the engine was serviced and the engineer said there was a fair amount of fine grit in the fuel filter. After around 100 hours we changed the filters again, and found the primary one was again quite heavily soiled, but the secondary one on the engine clean.
A further 80 or so hours since, the primary filter bowl is again full of grit (very fine, like dust almost) - its on the list to change it again before we next used the engine.

The engineer said that by using fuel cleaner (think we use Starbright's version) the fuel would be ok as long as we keep an eye on the filter, and that it should clear itself after a couple of tanks full have gone through.

We cannot get the tanks out to clean them - is it worth trying to get the fuel scrubbed, or should I persevere for a bit longer and keep changing the (£15 each) primary filters every 50 hours or so?

Incidentally, its reassuring to see the secondary filter almost spotless when we changed it - shows the primary is really doing its job (Its a Racor one with a plastic bowl on the bottom).

Jonny
 
How much does fuel scrubbing cost (ball park figures) - our tanks hold around 90 gallons in total (split between a main tank in the bilges (stainless) of around 70 gallons, and a day tank (to which we manually pump fuel from the main tank) behind the engine (stainless again) of around 20 gallons)??

Jonny
 
Even if you can't get your tanks out, it might be worth giving them a going over with a steam cleaner aka hot water pressure washer. Or open the inspection hatches and mop them out.

Don't forget the fuel lines too.
 
I would add a word of caution; relying on additives to "sterilise" fuel or a tank is probabaly mistaken. I think you have two options:

1. A thorough purge of the tank and lines, drying out and running fuel through to reduce residuals to the minimum

2. A policy of sludge control: empty the tank, filter the fuel, clean the lines through, and be prepared to inspect and change the first in line filter on a regular basis.

I pass on wisdom from an old engineer: folks fuss about engine oil filters because the oil in a diesel goes black so readily. Far better to spend the time and dosh on changing fuel filters regularly, even several times a season, if, on inspection, they foul quickly.

PWG
 
Re: Diesel sludge - here to stay? - fuel scrubber/conditioner

Just asked my local bloke and a ballpark figure would be £50/hour. That would the worst case, with restricted access to tank or boat etc. He says that usually it would be pretty quick and cheaper than that.

The fuel is scrubbed and "conditioned", either way it's cheaper than replacing 90 gal /forums/images/graemlins/smile.gif
 
Re: Diesel sludge - here to stay? - fuel scrubber/conditioner

Brilliant - thanks, in that case I may look at having it done. Wonder if there's anyone in Fleetwood does it (doubt it) - may leave it til the summer and see if there is somewhere enroute for us to stop into who can do it.

Jonny
 
Re: Diesel sludge - here to stay? - fuel scrubber/conditioner

When you say restricted access - could they do it through the filler pipes (for the main tank we have two - one on each side) - could they pump out through one and back in through the other to scrub it, or do they have to actually get into the tanks?

I appreciate you would want to get into the tanks re sludge, but I think my problem is more fine grit, so hopefully it would all be picked up by the moving fuel and flushed through.

Jonny
 
[ QUOTE ]
I'd double dose it with 'Soltron' and see what happens.

[/ QUOTE ]

I don't beleave it, 4 hours and nobody is slagging your cure /forums/images/graemlins/wink.gif
 
Re: Diesel sludge - here to stay? - fuel scrubber/conditioner

I don't know is the short answer! I have seen the rig, which is quite compact, but I didn't notice how the hoses were operated. I didn't ask if the fuel was recirculated, but I guess it would be because it is often used on big mobos, and they can carry more than a few jerries worth of fuel
 
I have just had the same problem. Discovered by chance that there was a huge amount of black, tea leaf like bits in the 65l tank. Now all cleaned out and refilled. Its funny that I had no trouble with the filters or engine running last year; must have been on borrowed time!

Mind you I think it's the first time the tank has been cleaned in 27 yrs.

All the usual precautions have been taken - tank always kept full, additives used in recent years. sedimentation bowl always kept an eye on and no water drops seen in 3-4 years

Here's hoping
 
I had the same problem a couple of years ago, so when I took out the diesel I let it settle then I filtered it rhough a pair of the wife's finest stockings. I cleaned the tank with gunk and a pressure washer and any other vcleaning fluids I could think off, dropped a fan heater in there for a spell to dry it out, and re-filled with the old diesel.

I treated it with one of the expensive anti bug things (Grotamar I thiink) that came out really well in the PBO tests (not Soltron) and have had no problem since.

I picked up the anti bug thing from the local fuel labs who use it / sell it. I was re-assured to see a real life lab of the sort I havent seen since Uni. Beats buying at the chandlers.
 
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