Fuel tank problem

[deputysitman]

Hi there fellow liveaboards....

I am having a repeat problem I have an ongoing problem of water ingress into my fuel tank.

I have drained 1/2 a pint of water from the first in line filter before any diesel has fallen through the bottom of the drain off valve....

Then I have sucked out from the bottom of my Diesel tank 2 pints of contaminated diesel.....

 

A mixture of water and muck.

The return fuel from the engine is clear also I Have checked the oil and that has no contamination.

 

1/ Do I have a leak under the water line ?

2/ I am going to check the filler cap and surround for any water leaks tomorrow.

3/ And how do I check if there is a leak only thing I can think of is by pressurising the tank itself or totally emptying the tank? ?

 

 

So as you can imagine I am a bit depressed ;-( any help any one has input I would be very great full.

 

chris

x

[RLWP]

Hi there fellow liveaboards....

I am having a repeat problem I have an ongoing problem of water ingress into my fuel tank.

I have drained 1/2 a pint of water from the first in line filter before any diesel has fallen through the bottom of the drain off valve....

Then I have sucked out from the bottom of my Diesel tank 2 pints of contaminated diesel.....

 

A mixture of water and muck.

The return fuel from the engine is clear also I Have checked the oil and that has no contamination.

 

1/ Do I have a leak under the water line ?

2/ I am going to check the filler cap and surround for any water leaks tomorrow.

3/ And how do I check if there is a leak only thing I can think of is by pressurising the tank itself or totally emptying the tank? ?

 

 

So as you can imagine I am a bit depressed ;-( any help any one has input I would be very great full.

 

chris

x

 

Hi Chris,

 

Can I ask some questions?

 

What kind of tank is this (Integral with the hull on a narrowboat?)

 

What kind of filler do you have?

 

When did you last fill up with diesel?

 

How full is your tank?

 

I'm interested to find out if this is rainwater, canal water, condensation or did it get put in with the diesel last time you filled up.

 

Richard

Edited August 30, 2009 by RLWP

[alan_fincher]

Where is the tank, please ?

 

Is it a standard offering where the rear part of the round counter is boxed off, to form the enclosure ?

 

If so, then the diesel level would be well above canal level. If there is a "hole" joining tank to canal, I'd expect diesel to drain out at least as easily as water gets in, due to the "head" above canal level. If it did escape, you would see it on the canal.

 

How old is the boat ? In the unlikely event something has rusted through, I understand a likely point of failure can be the tube the rudder stock passes through, as it is often not that thick steel, and because you can't black up a rudder tube. It should only happen in a fairly old boat, though.

 

I would have thought rainwater breaching the filler cap the most likely reason, (unless someone sold you "bad" diesel ?)

[deputysitman]

Hi richard,

Thanks for replying,

Here are your answers;

Wen

Integral fuel tank aft.

Brass filler cap,whasher intact around brass screw cap.

2 weeks ago bought 60ltrs full to the brim 40 gallon tank but went to York last week so used enough fuel for 36 hours cruising time, think its about about 3/4 full.

I did think condensation but the weather has not been cold enought for it ....

Oh it tastes awfull ;-( with a hint od diesel.....

 

chris

[DHutch]

Never been a fan of the flush brass fillers for fue. Ok for water tanks, and very nice, but a little vunerable to rain ingress.

- That said, they are common throughout the country, so much work for most, and with the washer in good nick, no reason they should seal.

 

Has this happended before (or since?)

 

 

Daniel

[Guest]

I have had exactly the same problem. The brass fitting was leaking where it joined the deck, so I cleaned it and sealed it with special silicon from halfords. The filler cap seal was brokeen too and I bought a new neoprene one for sixty pence. I added some Fortron to tank, and after settling, I pumped out all the crud from the bottom. It has been fine this year. The fault you have is very common.

Edited to add if your tank was leaking you would see loads of diesel on the water, as happened to mine. It is a good ida to pump out the bottom of the tank every season, and I have been amazed at the amount of crud in there.

 

Edited now that I am sober.

Edited August 31, 2009 by Guest

[deputysitman]

Hi alan,

Yes it is a standard fuel tank to the curved rear and the boat is 5 years old nothing really.

Willl try to check the rudder tube.

Most people have suggested the brass fuel filler cap going to re-seal that today.

[alan_fincher]

Hi alan,

Yes it is a standard fuel tank to the curved rear and the boat is 5 years old nothing really.

Willl try to check the rudder tube.

Most people have suggested the brass fuel filler cap going to re-seal that today.

If you are not seeing a Diesel slick in the cut, I doubt there is any hole between the tank and the canal.

 

At 5 years old, unless there is a really crap weld that has failed, it is certainly not going to have rusted through.

 

I agree with the others - filler cap fault, or a fill of "bad" red.

[deputysitman]

Hi there catweasel,

 

I have been shopping around for the cheapest "cherry" and also checking the quality befroe I add it to my tank so I do change my suppliers.

 

chris

[springy]

Hi Chris

 

A neighbour of mine had a similar problem - turned out to be poor welding where the rudder tube

meets the deck plate, there was never any sign of diesel leaking and the problem was erratic -

sometimes there would be water in the tank, other times it would be ok - it turned out to depend

on the nature of the cruising he'd been doing - when using full rudder and high engine revs the

water forced up the rudder tube was being forced into the tank & causing the problem, he does

have a fixed sealed ball bearing race at the top of his rudder shaft rather than a plain sloppy fit

sleeve which allows most of the water to just gush up onto the deck. Definately worth a look -

particularly if you have a sealed bearing at the top.

 

springy

Edited September 2, 2009 by springy

[RobinJ]

I am having a repeat problem I have an ongoing problem of water ingress into my fuel tank.

I have drained 1/2 a pint of water from the first in line filter before any diesel has fallen through the bottom of the drain off valve....

Then I have sucked out from the bottom of my Diesel tank 2 pints of contaminated diesel.....

 

A mixture of water and muck.

The return fuel from the engine is clear also I Have checked the oil and that has no contamination.

 

1/ Do I have a leak under the water line ?

2/ I am going to check the filler cap and surround for any water leaks tomorrow.

3/ And how do I check if there is a leak only thing I can think of is by pressurising the tank itself or totally emptying the tank? ?

1/2 a pint is not a great deal (in what time?), could be condensation, water in the diesel when purchased (suppliers have the same problem from rain ingress), rain or even canal?

1) Doubt it (not enough water, no loss of diesel?)

2) Good idea.

3) Pressurising would probably be the only way to check it, but it might have to be done out of the water? It is possible to get a leak on any weld or puncture a tank at any point (how old is it?), the most sensitive spot is usually at the back of the weed hatch where wear, water and heat are usually in the right proportions!

[deputysitman]

Hi there Springy,

This sounds very interesting....

I have had water come up the rudder tube a couple of times..when first getting use to the boat.

Now I am a bit more in control and don't get over enthusiastic with the throttle its not happened for a while but well worth some investigation..

Thanks much appreciated !!!!

 

Chris

[nb Innisfree]

Hi there Springy,

This sounds very interesting....

I have had water come up the rudder tube a couple of times..when first getting use to the boat.

Now I am a bit more in control and don't get over enthusiastic with the throttle its not happened for a while but well worth some investigation..

Thanks much appreciated !!!!

 

Chris

 

Been covered already quite recently, my cure was to put a grease nipple in the top bearing, another is to fix a rubber flap round rudder stock just below uxter plate (needs to be dry docked for this one)

[deputysitman]

Been covered already quite recently, my cure was to put a grease nipple in the top bearing, another is to fix a rubber flap round rudder stock just below uxter plate (needs to be dry docked for this one)

 

Hi there Innsfree,

Going to put an air test on the tank soon so will know one way or another what the problem is.

I have re sealed around the filler and bought a new Fuel Lock system so hope fully thats 1 problem out of the way.

 

chris