Water in the diesel tank

[sighmoon]

After motoring through the night and running down the fuel tank to about 1/4 full - lower than I'd let it fall before, the engine refused to start. I duly took off the fuel filter and had a look, and it was full of brown liquid, which didn't particularly smell of diesel, and leaving it to settle overnight, I reckon the tank must have contained about 2% diesel and 98% water.

We pumped it out, and there was about 3 bucketfulls of the liquid.

Where could the water have come from? It's a lot for a winter's worth of condensation, and there had been no problems at all when the boat was last used (last year). We'd had a bit of water over the decks, but the rubber on the deck filler cap was still soft and seems like a good seal to me. The yard we overwintered at had filled the water and diesel tanks for me, and I'm left wondering if a numpty at the marina may have put the wrong hose in the wrong hole, and kept quiet about it. Could there be any other explanation?

The water seems to have stuffed one of the injectors, so the saga isn't over.

Thankfully, this happened alongside a pontoon, shared with knowledgable and helpful motor boaters who dived in and sorted out what was what.

 

[chubby]

I once accidentally had the diesel tank filled with water by a crew member, genuine mistake, eventually sorted by inserting a semi rigid tube down the fuel filler, bouncing it off the bottom and sucking out the water until we got clean fuel and repeatedly emptying the water separator untin we got rid of the water, then keep a very careful eye on the water separator for months after, eventually all sorted, of course nothing as simple as a draiange bung at the bottom of the tank!

 

[Twister_Ken]

I'm left wondering if a numpty at the marina may have put the wrong hose in the wrong hole, and kept quiet about it.

Favourite for me, unless it's been collecting there for years. When did you last check?

 

[sighmoon]

Favourite for me, unless it's been collecting there for years. When did you last check?

I only bought the boat last year, but hadn't let the tank run quite so low before. I'll drop the previous owner a line and see if he ran it that low.

 

[Spyro]

. The yard we overwintered at had filled the water and diesel tanks for me, and I'm left wondering if a numpty at the marina may have put the wrong hose in the wrong hole, and kept quiet about it. Could there be any other explanation?

Leaves me wondering too, why would they fill the water tanks to leave over winter?

Water will sink to the bottom of the tank so why you were able to motor through the night baffles me. 3 bucket fulls is a lot of water. As the tank will feed from the bottom I would have thought problems would have shown up a lot sooner.

 

[sighmoon]

Leaves me wondering too, why would they fill the water tanks to leave over winter?

Water will sink to the bottom of the tank so why you were able to motor through the night baffles me. 3 bucket fulls is a lot of water. As the tank will feed from the bottom I would have thought problems would have shown up a lot sooner.

They filled it at the start of the season, not the end.

Yes, I don't really understand why the problem didn't show up as soon as we started the engine in the first place. The engine had gradually been needing more throttle to maintain the same RPM, and eventually cut out, and then we sailed a bit (in a rough sea, so perhaps shaking the tank up), and then it started fine again.

 

[Spyro]

They filled it at the start of the season, not the end.

Sorry, I just realised I understood that wrong:

 

[frankw58]

water in diesel tank

Hi sighmoon, the water in yr tank is partly condensation watre an dpartly water out of the diesel. The odays diesel is sulphur free and contains a part bio component made from plants. The diesel fuele is susceptable for bacterial growht, the brown sludge you found on your filter:
Actions to take to prebent; Suck with a hose as much as possbile bottom slime out of the tank (until "clearer diesel"pops out. Then add a biocide like Acticide CMG and refill tank.
This biocide will kill allleft over bacteria in all edges and trimms. These dead bodies you will find later in your filter. So you have to take a spare filter with you. After a while the problem will be over for a long time.

Hope this helps and give you time to enjoy your new boat

beste regards
Frank

After motoring through the night and running down the fuel tank to about 1/4 full - lower than I'd let it fall before, the engine refused to start. I duly took off the fuel filter and had a look, and it was full of brown liquid, which didn't particularly smell of diesel, and leaving it to settle overnight, I reckon the tank must have contained about 2% diesel and 98% water.

We pumped it out, and there was about 3 bucketfulls of the liquid.

Where could the water have come from? It's a lot for a winter's worth of condensation, and there had been no problems at all when the boat was last used (last year). We'd had a bit of water over the decks, but the rubber on the deck filler cap was still soft and seems like a good seal to me. The yard we overwintered at had filled the water and diesel tanks for me, and I'm left wondering if a numpty at the marina may have put the wrong hose in the wrong hole, and kept quiet about it. Could there be any other explanation?

The water seems to have stuffed one of the injectors, so the saga isn't over.

Thankfully, this happened alongside a pontoon, shared with knowledgable and helpful motor boaters who dived in and sorted out what was what.

 

[PeterR]

A few years ago at the beginning of a Sunsail charter one of my crew decided to be helpful and top the water up. Despite being an offshore yachtmaster he managed to put about a bucket full of water into an almost full diesel tank before he realised his mistake.

The Sunsail rep sighed heavily, ran the engine for about 5 minutes to demonstrate the controls and waited for it to stop. He then sucked out the water, drained the filters bled the system and all was well. Apparently its a regular occurance for them.

However, my point is a bucket full of water was enough to stop the engine of a 45 footer within 5 minutes at tick over so I doubt your 3 bucket fulls were all water. If they were they must have got in overnight.

 

[Metabarca]

I had this happen to me and the cause was bizarre (and took the mechanic quite a while to find): some very heavy rainfalls over the winter had caused the scuppers almost to fill and to allow water into the gas cylinder compartment on my stern (Centurion 32). The drain from this compartment happened to become blocked; the breather from the fuel tank happens to connect to said compartment...

 

[sailorman]

A few years ago at the beginning of a Sunsail charter one of my crew decided to be helpful and top the water up. Despite being an offshore yachtmaster he managed to put about a bucket full of water into an almost full diesel tank before he realised his mistake.

The Sunsail rep sighed heavily, ran the engine for about 5 minutes to demonstrate the controls and waited for it to stop. He then sucked out the water, drained the filters bled the system and all was well. Apparently its a regular occurrence for them.

However, my point is a bucket full of water was enough to stop the engine of a 45 footer within 5 minutes at tick over so I doubt your 3 buckets full were all water. If they were they must have got in overnight.

oil floats on water
the fuel pick-up is down to the bottom of the tank

 

[sighmoon]

Hi sighmoon, the water in yr tank is partly condensation watre an dpartly water out of the diesel. The odays diesel is sulphur free and contains a part bio component made from plants. The diesel fuele is susceptable for bacterial growht, the brown sludge you found on your filter:

Thanks Frank. The brown stuff was not sludgey, but fully liquid. It looked like a cup of tea (if that makes any difference).

 

[jac]

I had a problem that was similar

Turned out that the exhaust was chafing against the fuel filler and there was a small hole in both.

Most of the exhaust water went out the exhaust, some fell into the bilges ( which also explained where the water came from when we motored a lot!) but some went down the fuel filler and into the tank. Obviously the more we motored, the more water in their tank.

 

[Leif-J]

On my first boat I had a water-in-fuel problem, and it took me a full season to find the cause. Happened to be a leak in the tank vent, which was a copper tube going through the deck and up inside a stanchion. The leak was at deck level inside the stanchion. Every time it was rainy or water on deck, small amounts of water leaked into my diesel tank.
Not an easy one for a then newbie in boating!
Wishing you a good hunt for the cause - no way can three buckets be condensation!

 

[A1Sailor]

On my first boat I had a water-in-fuel problem, and it took me a full season to find the cause. Happened to be a leak in the tank vent, which was a copper tube going through the deck and up inside a stanchion. The leak was at deck level inside the stanchion. Every time it was rainy or water on deck, small amounts of water leaked into my diesel tank.
Not an easy one for a then newbie in boating!

Not surprised it took you a full season to work it out. I take it you felt somewhat accomplished after you'd worked it out - gosh!

 

[Deleted member 36384]

A diesel heater on my boat was removed along with the tank which measures about 75 cm x 20 cm x 10 cm. I decanted the contents of this tank into my engines starboard fuel tank. About half way through the process the red diesel turned to a tea coloured liquid that appeared to have a lower viscosity than diesel.

I am sure that the tea coloured contents is a mix of bug bodies, water and other stuff that settles out over time. On my drilling rigs we centrifuge diesel and the obtain a waxy tea coloured crud. So my assumption is that whats in the tank is not straight water but a combination of other impurities built up over time.

Coincidently, not, my starboard filter which was new is now showing high vacuum pressure. There is no water in the water trap of the filter. I would recommend that you open the tank and clean out the crud. In my experience water looks like water and is evident as a more or less (not tea coloured) clear liquid . Its obvious when there is water in the water trap from the colour differentiation.

 

[Leif-J]

Not surprised it took you a full season to work it out. I take it you felt somewhat accomplished after you'd worked it out - gosh!

It learnt me how to empty water separator quickly, and also how to moor without motoring.
Got me quite a few comments on sailing skills - actually it was mostly just emergency!
But yes, you get to know a bit of your vessel.

 

[Sybarite]

Leaves me wondering too, why would they fill the water tanks to leave over winter?

.

Leaving the tanks full means that there is less air for bacteria to develop.

 

[nimbusgb]

Leaving the tanks full means that there is less air for bacteria to develop.

The black 'coffee grounds' type of diesel bug is actually anerobic, lives at the fuel/water interface and is a sulphur reducing bacteria or SRB and it produces hydrogen sulphide as a by-product of metabolism. Combined with moisture, strong sulphurous acids are formed.

Less air in the tank limits the amount of water deposited through condensation though.

 

[Deleted member 36384]

The black 'coffee grounds' type of diesel bug is actually anerobic, lives at the fuel/water interface and is a sulphur reducing bacteria or SRB and it produces hydrogen sulphide as a by-product of metabolism. Combined with moisture, strong sulphurous acids are formed

Do you think this would result in the "tea" coloured contamination?