First problems

[Mattyb]

So I have been going over my new to me boat and have stumbled on to my first problem. I took a look in the top of the fuel tank and the diesel was very cloudy. I siphoned some out and you can see from the pic below it doesn't look good. The bottle next to it is fresh diesel I had.

The bigger problem is I noticed that the approx 500 litre steel tank in the engine rooms tube from the bottom goes into the floor of the engine room and at the other end there is an inspection plate and this is where the fuel pick up seems to be from. There is 900 litres on Board! The previous owner had never filled it up and never used it much but only owned it for a year so not sure why there is so much in the main tank. There are no fuel polishers here And I have no idea how to handle 900 litres of fuel while i try to clean out the tanks, The fuel smells like turpentine so am thinking of just getting rid of it, Maybe even remove the steel tank and put in a new on?

any suggestions appreciated.

[daddle]

Steel tank with diesel? I think that is bad. Perhaps it is iron? (Someone?)

Some farmer or fisherman type will take the fuel off your boat, I would think. It looks terrible.

[garrobito]

..tried to polish the diesel, and clean the whole circuit (including inside the tank).
Don't be shy, even between the baffles.. more you clean, better diesel quality.. If you polish enough maybe you can save some of that diesel.. burn completely before pour new one.. replace main filter too off course.. a double racor diesel filter with a 2 micron and 10 micron could do the trick...

[Steadman Uhlich]

Originally Posted by Mattyb

So I have been going over my new to me boat and have stumbled on to my first problem. I took a look in the top of the fuel tank and the diesel was very cloudy. I siphoned some out and you can see from the pic below it doesn't look good. The bottle next to it is fresh diesel I had.

The bigger problem is I noticed that the approx 500 litre steel tank in the engine rooms tube from the bottom goes into the floor of the engine room and at the other end there is an inspection plate and this is where the fuel pick up seems to be from. There is 900 litres on Board! The previous owner had never filled it up and never used it much but only owned it for a year so not sure why there is so much in the main tank. There are no fuel polishers here And I have no idea how to handle 900 litres of fuel while i try to clean out the tanks, The fuel smells like turpentine so am thinking of just getting grid of it, Maybe even remove the steel tank and put in a new on?
any suggestions appreciated.

Howdy!

Given your photo of the fuel samples, I would suspect the fuel in your tanks was contaminated with water rather than biological growth.

Why?

You mention that the PO had no idea how there was so much fuel in the tanks.

That leads me to suspect that someone mistakenly filled the fuel tank with water by mistake. This could have been a simple human error at a dock.

I will post a photo showing two fuel samples, with the cloudy one due to water contamination.

Good luck and have a happy new year!

[Mattyb]

hmmm steady hand you may be on to something there. The previous owner said it was about 75% full when he bought it but I think that he may have just looked at the gauge ( which is faulty) However it is almost full to the top and the 2 water separator filters don't seem to have any water.Would the water settle out in the jar I got out of the tank?

Water does make sense though. We took her for a test sail before buying and were motoring for a good 2 hrs so not too sure.

Day after tomorrow I will remove both inspection hatches and see what it looks like in the one under the engine. Would make sense also for the smell I guess too.

[Mattyb]

Actually the plot thickens. The tank below the engine is always full as it draws from the other tank in the engine room.

The PO said he had run aground and had layer her over. I bet she took in water through the breather ( haven't located exactly where she exits yet though ) and has contaminated the main upper tank. Because she hasn't been used since then there wouldn't be much fuel drawn into the bottom tank. Does that sound feasible?

I guess If I lift the plate on the lower tank and she looks ok then that would explain it. Just have 500 odd litters of watery diesel to get rid of then.

[Steadman Uhlich]

Hi.

Your plot does thicken.

I am no diesel mechanic or expert, and I am sure others here will have much more experience with diesels, but as I understand it:

A boat may have a small "day tank" that is used to hold prefiltered fuel and is usually near the engine, perhaps in an engine room. The day tank would or could be filtered multiple times before the fuel hits the engine. The purpose being to have a pre filtered "clean" source of fuel ready for the engine.

A larger fuel tank, possibly contaminated by water, possibly by human error when filling the "water" tank at the dock, or by some other water ingress, would be separate from the day tank.

Note! People have been known to accidentally fill a fuel tank with water, by mistake, and the opposite too. Some boats have flat deck fill plates that look very similar or even identical. A good thing to do on a new to you boat is to clearly identify all filler caps and clearly label them, so anyone can know what they are for, as others may be servicing the boat without your observation.

The boat could be used for a short time or the motor started using the day tank, as that fuel may have been untouched by the water, and of sufficient quantity to start or demo the engine, or motor for a while.

I hope this helps you. I am sure others here can offer more details or experience or suggestions.

Good luck.

If your investigation finds the cause, I hope you will report your findings as it may help others, including me. I come here to learn from the good and bad experiences of others.

[Steadman Uhlich]

Also, if your boat does have a day tank, it would be a good thing to know the capacity and hence the possible motoring time one might get from it, if the larger tank become fouled.

[darylat8750]

I had a similar problem in Mexico. The fix is not easy but it is not horrible either. I borrowed five 55 gallon drums from a petrol wholesale business. If you can get the plastic translucent ones it makes keeping track of level easier. I took out my Racor filters and mounted them on a small plywood board. Added a continuous duty fuel pump. (Always suck through the Racors.) I plumbed from the fuel feed to the filters then pump thence to a Baha filter and then into a clean drum. When a tank was empty I pumped some cleaned fuel in through the Baja filter and back out to rinse the tank. I let the barreled fuel sit overnight to settle then pumped the top portion of each barrel back through the Racor and Baja filters into the tank. A couple of the barrels were obviously more contaminated than the others and I stayed further from the bottom on those than the others. I then pumped the dregs of all the barrels into one and let it settle overnight. I double filtered some of that back into my tank but left SEVERAL gallons because it was just too dirty to deal with. I went through almost two cases of 2 micron Racor filters.

A couple of points to consider. Even after going through the Racors the Baja filter got a lot of water out. When the funnel started fillin up because of crud build up it is time to clean the filter. If you touch the metal filter element it with fue and water in it that seems to change the surface tension and water will go right through it. You need to stop the flow, dump the crud and rinse with fuel before starting again. Nothing can beat getting into your tank and scrubbing and rinsing it but if you can't do that you might consider putting about one fourth of the capacity back in and finding some rough water to head into to shake it up good then going through the filter process again.

You might also check the seals on your fuel fill ports. I have seen bad o rings that allowed rain and sea water leak into a tank.

It took me 4 days to do two tanks of around 400 gallons total. I haven't had an issue since.
Good luck.

[CS Cruiser]

Don't bbq those samples! ��

[Mattyb]

Thanks to all. I don't think it could be an accidental water fill up but I can see how others have done it. Our fuel is actually filled in an opening on the tank. There is no deck fill etc.

Daryl, I think that I would almost give that a go. I am going to look into how much it would cost to dump it though first, am a bit paranoid about these things. Last thing I need is the engine to quit on me right when I am pulling up to the mooring piles which are in a tight spot and 25 tonne will be hard to stop then. I wonder if mine is too far gone, seems to really smell different.

[Mattyb]

Steady hand, it's about 500 litre day tank. Should get plenty out of that

[Nicholson58]

Originally Posted by Steady Hand

Howdy!

Given your photo of the fuel samples, I would suspect the fuel in your tanks was contaminated with water rather than biological growth.

Why?

You mention that the PO had no idea how there was so much fuel in the tanks.

That leads me to suspect that someone mistakenly filled the fuel tank with water by mistake. This could have been a simple human error at a dock.

I will post a photo showing two fuel samples, with the cloudy one due to water contamination.

Good luck and have a happy new year!

I also agree. - probably water. This is easy to confirm. Add a solvent like laquer thinner to a sample & shake. this will reduce the viscosity so that water in the sample can drop out. You may be surprised at how little water it takes to make fuel look like that.

I had to get rid of 300 gallons of old fuel when we bought our boat. The nearby truck yard took it from me & did the cleaning. I pumped off into used 55 gallon drums using my water/fuel separation BAJA funnel (picture) There are a lot of water removal funnels shown on a search. We$t Marine carries a few.

Take a representative sample and see how long it take for the water to separate. You need to wait at least that long before sucking the water layer off the bottom of the tank. Is there water in the RACOR?

There are water/fuel separators you could use if you can get one.

Water can also enter by your deck fitting if the O-Ring is bad. Our local marina inspects & replaces FREE all bad O-Rings. Another option is bad fuel outright.

[Cheechako]

I have seen darker diesel than that (old). If water, you shouldn't be running as the water is on the bottom part of the tank... right? Did I read that your tank outlet is on the tank bottom? if so, could you remove the hose and take out a litre or more. Let it sit overnight in a jar and see if it separates into water-diesel.
The easiest may be to polish your own tank... can you set up a system to do it yourself?

[darylat8750]

Even if you dump it a good clean and rinse of the tank would be in order.