NormanS
Well-known member
Our twin 50 gallon tanks are both equipped with sumps with drain valves, so it is very simple to drain off any water or dirt, should there be any.
To empty, or not?
- Thread starter Ink
- Start date
FairweatherDave
Well-known member
This concept of brimming..... I reckon I have about an inch below the top of the tank, not including the filler spout. So I could squeeze in maybe 2 or 3 litres more. Concerned I might have a breather pipe and I start inadvertantly filling the bilges. Obviously I should crawl into the locker and take a look but any wisdom here? I'm guessing given the boat heels from time to time ...... Standard replacement steel tank in a Konsort.
dunedin
Well-known member
Except that the whole point of the original letter was that things have changed to the diesel composition in the past couple of years - hence the question about whether to change approach.
Experience and techniques from 15-20 years ago (that many/most of us have) may no longer be relevant
PS. Our first ever diesel issue was last year, after many years entirely trouble free, so perhaps be careful
Chris_Robb
Well-known member
In Greece we now have been using up to 10% FAME in the diesel. Over the last 8 years or so, I have a sump and take samples of fuel a day after I fill up. The is always about 2 or 3 egg cup fulls of a blag waxy liquid. I let this settle and decant the good (which is nice and bright) back into the tank. I kept the black waxy liquid topping it off each time I refilled. So refueling over 1 year and ONLY 100 hours of engine time (2003T Volvo) this amounted to about a 1/4 of a small coke bottle. I passed this stuff experimentally through a filter paper which blocked up instantaneously.
Oh Dear - I wonder how many yachties can effectively draw off from their sumps easily, and if they cant, I wonder over 8 years of this stuff's use in the Med how much this will have accumulated - I do a relatively small number of annual hours for the Med (No Wind or Too much wind!)
I tried to get it analysed in the UK - but every site I spoke to wanted £500 . I suspect its the drop out from the FAME vedgy oil - which incidentally is very hydroscopic and a joy for the bug to feed on and it is this that causes a recommendation of 3 months tank life
I run my tank down and leave it normally about a quarter full.
Is this a ticking time bomb in the Med where you have no alternative to Fame in the fuel?
dankilb
Well-known member
Ah, don't read my 'brimming' 100% literally! You don't want fuel sloshing up the filler/breather.
I'm no expert, but my understanding was that - if planning to leave diesel in the tank - filling it 'as full as reasonable' is advisable because it reduces the volume of air (and therefore moisture, potential condensation, and risk of water ending up in the fuel). So an inch from the top (and a couple of litres' air capacity) sounds pretty good to me - and a lot better than half full!
BTW, I've left vehicles with half full or nearly empty tanks that have run fine after a year or two. After a quick test, I also ran a (modern) van off 150L of 7 year old diesel I inherited with the current boat and saved a few £££ in the process. So I'm not in the 'protect (or avoid!) your stagnant diesel at all costs' brigade, by any means!
Sandy
Well-known member
I'd be interested in the results of this experiment if you did this with some modern fuel.
WoodyP
Well-known member
I use it in a tractor. It's easier to walk home from the bottom meadows than from a hundred miles away.
dankilb
Well-known member
No idea! Are there additives/bio content now that there wasn’t before?
I should add - I’d only run old fuel under moderate duress (e.g. when you need to moved stored vehicles around the yard or in my case to dispose of all that old diesel - rather than run it in the boat). I’d never try it with a common rail either (not sayin it would/wouldn’t break it - never had one!).
PeterWright
Well-known member
This is true if you are using white diesel bought at a roadside filling station intended for use in cars. However, if you're using red diesel from a reputable marine supplier it should be Fame-free (free of fatty acid methyl ester, the bio component) so the traditional advice still applies.
It all depends what you have in the tank!
Peter.
HissyFit
Active member
Sailing Cadoha put up this video of an interview with the MD of Marine-16. It certainly changed my mind about the whole fill/empty tank thing.
Sailing Cadoha with Marine-16.
Sailing Cadoha with Marine-16.
dunedin
Well-known member
Thanks. Brilliant and very informative video.
Clearly Marine 16 are selling a product, but there is a lot of very useful information in there. And confirms strongly that experience of ten years ago does not mean that it remains applicable today, with so much change to the diesel distillation processes.
One thing about the dipper system, it looks like it needs a LOT of height to install. That could be an issue on many boats.
dunedin
Well-known member
I am no expert, but from other experts posting on here previously who are apparently in the trade, they suggested that due to the precise regulations on formulation (and allowed amounts of Fame before labelling as such), there may be no way of even the supplier knowing if a supply is entirely Fame-free, so the signs on marina tank may be meaningless.
Certainly we got diesel bug earlier this year, and as far as we were aware it was all from reputable marine suppliers, so i would suggest don’t be over confident.
dunedin
Well-known member
and as well as this video, on the Marine 16 website they have their own explicit answer to the OP's original question, to drain or fill - Marine 16
which amongst other very helpful suggestions, their answer is "why don’t we recommend topping the tank up any more" ........."we recommend running the fuel tank down to as empty as possible"
This page is also very informative Marine 16
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Sandy
Well-known member
I wonder if 'a reputable marine supplier' actually knows what they have in their tanks?
Do you ask to see the batch certificate each time you fill up? What happens if the driver makes a mistake and delivers the wrong stuff?
I understand that red diesel is only dyed for tax reasons and nothing special.
Graham376
Well-known member
I must admit to being totally confused about differences between red and white although for myself, I've no alternative but to use white. According to Crown Oil - Red Diesel Fuel FAQ: Usage Rules, Taxation Changes & more | Crown Oil
Red diesel is virtually the same as regular diesel, but with a red dye added to it to prevent it being used on road-going vehicles.
Ink
Active member
Idle curiosity - how do you determine 'reputable marine suppliers' of diesel? Do they have signs up ??
I normally get handed a fuel nozzle and start filling up. There's normally no discussion with the person who hands me the fuel nozzle as the chances are they don't know what's coming out the nozzle and generally don't care.
Ink
RobWard
Member
That wasn't my experience last year - 2 out of the 3 marinas I filled up at we're keen to explain why I could trust their fuel.
The 3rd - maybe less so.
The 3rd - maybe less so.
Sandy
Well-known member
What was their explanation and did they have any paperwork to backup their claims?
Nito
Active member
Thank you for this valuable information. Our situation; we have a Sunseeker Portofino 400. It has 990L tankage with largely inaccessible tanks , no cleaning points and removing them is an engine out job. There is no tank drain as such, although there is a pump out point which is effectively a dip tube that is positioned 10mm from the bottom of the tank.
The previous owner had bug issues in the past and had had the fuel polished. We brought our new to us boat home with a full tank of diesel in May last year. On navigating around the coast, we filled the tanks to the brim at our home port where it had about a third left in it on arrival. By late August we were still on this tank albeit about 1/2 full when we had our first problem. One engine (stbd) dropped rpm. It literally hit a ceiling that it wouldn't rev beyond 1600rpm. I throttled back and re-applied, after doing this a couple of times the issue went as quickly as it came. A week later, the same again, I throttled down and reapplied it went again, no black smoke either time. A week later we went out, no issues this time. The very next day, we went out again, this time as we banked left turning into the port it came back, same engine 1200rpm ceiling this time. (again no black smoke). The tanks were now reading a third full.
Following this experience I changed the fuel filters. Both bowls have always looked fine, no water ever in them. The filters were covered in bug. Arguably the Port engine filter was worse than starboard though we never had this rpm issue with that engine. We changed primaries and secondaries on both engines.
I began to suspect that bug or film was blocking the feed line to the starboard engine, perhaps clinging to the gauze or mesh that would be on the end of the feed tube. The intermittent nature of the problem made me feel it wasn't a mechanical problem with the injection units/fuel pump. Our engines are mechanical injectors. I spoke with Marship about their Diesel Dipper which I had previously read up on. By then I had dosed the tank with Fuelset, something the previous owner used and there was a bottle of it on board. They didn't recommend Fuelset because it effectively absorbs the water up into the fuel, which is the opposite of what you are trying to achieve with the dipper.
Thinking the low fuel level didn't help we also topped the tanks up to 1/2 tank. Next time out, banked left and same again, 1200rpm.
So back on the phone to Marship, long story short, the bug requires water to breed, eradicate the water eradicate the bug. I purchased their Diesel Dipper and Marine 16 diesel bug treatment and diesel injector cleaner. The DBT to kill the bug, the DIC to afford lubricity for the injectors, especially as water would have been absorbed into the diesel by the Fuelset and modern diesel being low sulphur removes much of the lubricity out of the diesel which can't be good for the injectors. We added this lot to the tank and I am in the process finally of finishing the dipper install so it will be interesting to see what happens next. I'm of the opinion that Fuelset type additive is not good, how much water can be absorbed into the diesel before it becomes saturated, not to mention it won't do the injectors any good?
While installing the dipper, I was vacuuming around the pump out point on the tank and sucked a load of diesel up, only it was clear like water. I turned the hoover off and the fuel than came out was a pale pink. Bottle on the right is vacuumed 10mm from the bottom of our tank. (The new dipper installation will go all the way to the bottom). The bottle on the left is from the Separ primary filter bowls.
Clearly we have some water or heavily saturated diesel in the bottom of the tank. I'll post more when the dipper is up and running, having spent a fair amount of money and time on the purchase and installation/research etc I'm looking forward to seeing the outcome.
This was the same advice they gave me, largely down to the FAME composition of modern diesel. They recommended running the tanks down in the winter, and dealing with the water content (ie with the dipper) on a relatively small amount of fuel before filling up for the new season.
Cheers
Nito
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Frogmogman
Well-known member
Interesting post. Thanks Nito
