Water in the diesel tank

[RichardS]

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.

I think some confusion is setting in between leaving water tanks full and leaving diesel tanks full.

I would have thought : water tanks empty, diesel tanks full - but I may be wrong!

Richard

 

[Sybarite]

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.

.

When you cant argue you just try to blind with science...!!

 

[Twister_Ken]

I think some confusion is setting in between leaving water tanks full and leaving diesel tanks full.

I would have thought : water tanks empty, diesel tanks full - but I may be wrong!

Richard

I second that emotion.

 

[nimbusgb]

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

Only if the fuel/bug mix is well agitated!

The OP's problem is really odd. As someone has said already the fuel pickup is at the bottom of the tank so how the engine kept running with all that water in it is anyone's guess!

 

[A1Sailor]

OK - the engine was running, stopped, and the fuel tank was found to contain lots of water. An injector seems to be damaged.
Is it possible that the cylinder head gasket has blown, allowing cooling water in; or, the fuel return pipe has suddenly started getting water from somewhere and sending it, not diesel, into the tank?
I can't work it out...

 

[david_bagshaw]

OK - the engine was running, stopped, and the fuel tank was found to contain lots of water. An injector seems to be damaged.
Is it possible that the cylinder head gasket has blown, allowing cooling water in;

would the cooling circuit have that much water in? no, so completely unlikely water could get into tank that route, not unless spill rails have some connection on the block near a waterway on a sea water cooled engine. if indirect the coolant loss would have been the issue, by overheat.


or, the fuel return pipe has suddenly started getting water from somewhere and sending it, and diesel, into the tank?
I can't work it out...

as others have said water filled tank would stop sooner, certainly not after hours.

where is the tank? leaky gauge mount, tank lid , cracked weld, plumbing & vent, allowing the water in at a sailing heel perhaps?

 

[Porthandbuoy]

Does the tank drain naturally towards the fuel pick-up? Mine didn't, so the only time I got water in the separator bowl was after a bit of a slog into a chop.
I chocked the forward end of the tank and was able to remove about a litre of cruddy brown stuff (only a 45 ltr tank).

 

[sighmoon]

as others have said water filled tank would stop sooner, certainly not after hours.

where is the tank? leaky gauge mount, tank lid , cracked weld, plumbing & vent, allowing the water in at a sailing heel perhaps?

The tank is just under the settee berth, so I don't think any of those could be the source, except perhaps the vent; I'm not sure where the ent is, but will investigate.

S

 

[sighmoon]

Does the tank drain naturally towards the fuel pick-up? Mine didn't, so the only time I got water in the separator bowl was after a bit of a slog into a chop.
I chocked the forward end of the tank and was able to remove about a litre of cruddy brown stuff (only a 45 ltr tank).

It seems pretty much flat at the bottom.

Do you believe your cruddy brown stuff had been in there a long time before you discovered it?

 

[nimbusgb]

In your case what's confusing is that the motor ran for a long while before packing it in. The fuel pickup in my tank doesn't actually go right to the bottom of the tank but rather draws from about 1/2 inch above the bottom. I presume to enable water to gather at the bottom and be drained off from the low point drain.

Possibly as you consumed diesel the percentage of water in the tank went up until the motor quit but this is usually preceded by needing progressively more throttle to maintain revs.

I'd be very surprised if cooling water either from the jacket or the heat exchanger side was getting in to the fuel return line. It would have to find it's way via the injector pump I think, highly unlikely! The only other way would somehow be via the mechanical lift pump but I'd expect oil in there before water. I think the motor would quit quite drastically, over temp or otherwise before quietly drowning itself that way!

 

[sighmoon]

Possibly as you consumed diesel the percentage of water in the tank went up until the motor quit but this is usually preceded by needing progressively more throttle to maintain revs.

Yes, more throttle was needed for the same revs.

 

[nimbusgb]

Yes, more throttle was needed for the same revs.

Ahh. Looks like the water had been there for a while then. Probably a leaking breather, condensation and contaminated fuel from the pump / bowser building up over time.

Drain it all down ( keep it in jerry's, let it settle and skim off the good stuff ) flush out the tank, lines and separator thoroughly, replace the filter/s. Dose with bug treatment, put in some fresh fuel and off you go. Keep an eye on the separators!

 

[Chris_Robb]

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

Hi Frank. Marine red diesel does not have Bio in (FAME). Also it could never produce that kind of quantity.

 

[Chris_Robb]

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

Unless you are in Greece and have road fuel with Bio. You then leave the tanks empty to avoid the hydroscopic effect and also the solidifying of the Bio.

 

[Chris_Robb]

In your case what's confusing is that the motor ran for a long while before packing it in. The fuel pickup in my tank doesn't actually go right to the bottom of the tank but rather draws from about 1/2 inch above the bottom. I presume to enable water to gather at the bottom and be drained off from the low point drain.

Possibly as you consumed diesel the percentage of water in the tank went up until the motor quit but this is usually preceded by needing progressively more throttle to maintain revs.

I'd be very surprised if cooling water either from the jacket or the heat exchanger side was getting in to the fuel return line. It would have to find it's way via the injector pump I think, highly unlikely! The only other way would somehow be via the mechanical lift pump but I'd expect oil in there before water. I think the motor would quit quite drastically, over temp or otherwise before quietly drowning itself that way!

The loss in revs would perhaps have been caused by one of the injectors stopping working before water got to all of them.

It sounds like you tank, under the saloon bunk, is long and flat, so if the fuel take off might be 2 inches of the bottom, there could have been a lot of water in there for a long time. Motoring in a flat sea would not stir up the contents, but a rough sea would.

I would also bet that the water is getting in through the vent, or may have accumulated over a very very long period.