Diesel Bug Chapter 2; am I just wasting my time?

[lw395]

I've just cleaned out my tank, luckily it had a nice large hatch and it was relatively easy to get into. On the bottom of the tank was loads of said black goo although the diesel itself was clean. The idea of a diesel polisher makes sense but I am very sceptical that it would have lifted all the goo from the bottom of my tank as it was stuck to the bottom of the tank. I had previously tried sucking up diesel from the bottom of my tank with a heavy duty Pela and there was no sign of bug but as the filter continued to block every 20 hours or so I eventually bit the bullet and emptied the tank and there it was.

There are several flavours of diesel contamination.
As I see it, the simplest categorisation might be 'bug' and 'tar'.
Tarry deposits (aspheltene?) stuck to metal surfaces seem to me to be a different phenomenon to the 'live' organisms digesting the diesel.
Of course it's possible to have a mix of both.

 

[steve yates]

What is the fascination with fuel polishing? Would it not be more logical, if you have a prblem in your tank to pump out all the contaminated stuff and dispose of it? Do whatever you need to the tank itself, but just start again with fresh deisel. Since most folk think a 40l tank plenty big enough, why go to the hassle to save £30 quids worth of potentially dodgy fuel? and if it's a big tank, and full, then pump out the top half or two thirds first and keep it if all ok.

 

[pvb]

What is the fascination with fuel polishing?

If you have a tank which is basically inaccessible, fuel polishing is one way of getting a lot of the rubbish out of it.

 

[lw395]

What is the fascination with fuel polishing? Would it not be more logical, if you have a prblem in your tank to pump out all the contaminated stuff and dispose of it? Do whatever you need to the tank itself, but just start again with fresh deisel. Since most folk think a 40l tank plenty big enough, why go to the hassle to save £30 quids worth of potentially dodgy fuel? and if it's a big tank, and full, then pump out the top half or two thirds first and keep it if all ok.

A lot of tanks are much bigger than 40 litres.
It costs money to get rid of a hundred litres of diesel.
It used to be more of a motoryacht thing, where 500 litres of fuel is not uncommon.

And actually cleaning a tank is difficult foul work.

Connecting up a polisher takes ten minutes, less if the tank is set up for it.

 

[neil1967]

What is the fascination with fuel polishing? Would it not be more logical, if you have a prblem in your tank to pump out all the contaminated stuff and dispose of it? Do whatever you need to the tank itself, but just start again with fresh deisel. Since most folk think a 40l tank plenty big enough, why go to the hassle to save £30 quids worth of potentially dodgy fuel? and if it's a big tank, and full, then pump out the top half or two thirds first and keep it if all ok.

We have a 500l tank but use relatively little diesel - I've not bought any in 3 years - so I polish the fuel around twice a year, just to ensure that nothing untoward is happening. Polishing is simple and not only ensures the fuel is clean, it also provides an indication if problems are developing. I use a home built system, with a copper pipe on the inlet so I can get into the bottom corners of the tank. Why wouldn't you polish fuel regularly?

 

[pcatterall]

Fascination with fuel polishing?

We have 2x 250 L tanks. I have set up my polisher to ensure that fuel pumped from the reserve tank is clean. When we start up after leaving the boat for a month or more we pass and check a few litres from the working tank and examine for water or crud before starting. Like Neil1967 we also pass larger quantities through the system twice per season.

 

[wotayottie]

We have a 500l tank but use relatively little diesel - I've not bought any in 3 years - so I polish the fuel around twice a year, just to ensure that nothing untoward is happening. Polishing is simple and not only ensures the fuel is clean, it also provides an indication if problems are developing. I use a home built system, with a copper pipe on the inlet so I can get into the bottom corners of the tank. Why wouldn't you polish fuel regularly?

Because its unnecessary? Been sailing for 35 years and had the bug 3 times but in each case it was when I had just bought the boat. Once the tank was cleaned and the incoming fuel treated, no further problems in my ownership. And thats cruising the uk coast from east anglia to Oban, the French coast and the spanish coast.

If you arent careful you can become paranoid about all sorts of boat problems but mainly engine and osm osis.

 

[Moderator]

The link doesn't work (Windows and iPhone), could I trouble you to point me in the right direction, please?

I have no immediate need but making one of these does seem to be an excellent winter project.

David


here's one with pictures.

http://www.ybw.com/forums/showthread.php?487003-External-Fuel-Polishing-Rig&highlight=fuel+polishing

The forum expert is Superheat; harken to his wise words

 

[BobnLesley]

What is the fascination with fuel polishing? Would it not be more logical, if you have a problem in your tank to pump out all the contaminated stuff and dispose of it? Do whatever you need to the tank itself, but just start again with fresh deisel.

That's my approach too, but we only had about 30-40 litres in our 100 litre tank when the problem first arose and have since twice added 25 litres and then later removed it in our efforts to flush out our contamination. An engineer in the marina tried offering to 'polish' my fuel, but at $100 a time, that's four or five times the value of the fuel and the marina were more than happy to take my contaminated fuel, they're settling it out in a drum and then going to use the majority of in their grass mowing tractor.

IMO fuel-polishing comes into its own when you're dealing with the mobos, if you've got a 1000+ litre tank then it makes financial sense, also I'm given to understand that the process works much better on larger sized tanks too?

 

[pvb]

IMO fuel-polishing comes into its own when you're dealing with the mobos, if you've got a 1000+ litre tank then it makes financial sense, also I'm given to understand that the process works much better on larger sized tanks too?

As I said in post 23, if you have a tank which is basically inaccessible, fuel polishing is one way of getting a lot of the rubbish out of it. In my case, it was a keel tank which would have cost several thousand pounds to remove for conventional cleaning.

 

[PaulRainbow]

The big classic motor yacht i'm rewiring at the moment (see here) has two very large tanks under the helm, Lord knows how you gain access to them (probably a chainsaw ) They hold 700 gallons, yes that is gallons, not litres !!

 

[NormanB]

Following on from last week's post I opened our tank's inspection plate and using a Pela type pump and lots of industrial alcohol I drained and flushed several times the tank to the best of our abilities. Sadly the tank's inspection opening only allows me to reach half the tank due to a baffle plate - I could and did get the pela-pump's pipe beyond - and the inaccesible half is the low point; even transfering 100+kg from stern to bow, plus getting three people to stand on the bow's not sufficient to fully counteract that; poor installation, but hey, Greek engineers installed it so what else would I expect?
So, the tank's clean other than the bit that won't come, hopefully just a pint or two, but that's really just a guess, poured in 6 -gallon of clean diesel and a serious dollop of biocide, then bled the system and re-started. It ran at tickover/moderate revs for an hour hour then stopped. The following morning I changed the filters, re-started and got almost two hours out of it; yesterday I did nothing and today with new filters I'm up to 2.5 hours and still going.
Getting the tank out will be a b*****d of a job, at best I suspect that I'll need to haul out and remove the engine-inlet seacock; but will the current policy actually clear it eventually? I've got a week to sit and let it run and a big box of Delphi primary filters to provide replacements, though perhaps not as many Yanmar secondary/fine filters (today it's running on the old one). Can I realistically expect it to clear eventually, or am I just going to have a repeat performance in another two or three days/weeks/months?

It sounds as though your contamination is beyond the help of polishing -unless you can agitate the tank debris continuously. Accepting that your tank will be truly difficult to remove is there anyway you can gain sufficient access to cut. new access hole in the currently inaccessible side of the tank.?

It may mean you have to remove or cut holes in bulkheads or cupboards but it will be worth it.