Water in diesel tank

[WJM]

It is fair to say that unless you use an emulsifier additive, then all narrowboats will suffer from water in the diesel tank (and there are negative opinions about the use of emulsifiers). So how to get it out before it becomes a problem?

 

I bought a very simple hand pump on eBay, dropped it into my diesel tank so that the pickup was right on the bottom of the tank. I then pumped perhaps five litres into a clear container. I let that settle for ten minutes or so. Yes, a layer about three inches thick at the bottom of the container that was definitely not diesel. I pumped again, another five litres and again let it all settle. Then I had about four inches of 'not-diesel'. Repeat the settling and pump again. Still four inches of crud. Assumption: I had now extracted most of the water. I let the container settle and then pumped back most of the clear red diesel, leaving behind perhaps a litre or two where I daren't risk picking up the water under it.

 

It was a really cheap and simple procedure. Ok, it is not 'Fuel Polishing', but I already dose heavily with Marine-16 so diesel bug is not my concern.

 

I thought the information might be useful.

 

Pump:

http://www.ebay.co.uk/itm/281234891509?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

[Barry]

Mmmm nice looking pump

 

thanks

[richardf]

I use this http://www.kolorkut.co.uk/ - water finding paste. Simply put a tiny bit on the end of a piece of timber dowel. Submerge until it hits the bottom of the tank - extract and see if it has changed colour

[OldGoat]

That's a great looking pump!

 

There was an awful lot of water in the tank, perhaps it would be prudent to perform the same procedure at regular intervals.

Also find out how the water is getting in. The breather pipe is the first candidate.

 

 

[mango]

An emulsifier will not be much use if there is much water in the tank. Water must be prevented from getting in via the filler cap and breather. If these are not the problem, you may have paid for this water when you bought diesel.

 

To pump out water from the tank, first heel the boat over in some way so that water collects in one corner of the tank and pump from there.

[MtB]

An emulsifier will not be much use if there is much water in the tank. Water must be prevented from getting in via the filler cap and breather. If these are not the problem, you may have paid for this water when you bought diesel.

 

I thought condensation was the major culprit.

 

MtB

[mango]

 

I thought condensation was the major culprit.

 

MtB

I think this is a myth. If condensation was the major problem then all diesel tanks would have a layer of water at the bottom. A simple experiment to try is to leave a container of diesel open to the atmosphere but with something over the top to prevent rain getting in. I have done this to prove the point for myself. I am not saying that condensation does not occur, but I don't believe that it is a major problem.

 

Deck fillers flush with the deck, with no cover can be a good way of collecting rain water and the spillage guard can act as a funnel. A seal on the filler cap might prevent water entering, but designing out the problem would be a better approach.

 

Common designs of approved tank vents are not much better. I saw one fitted adjacent to the rudder post on a boat. Every time the boat was reversed, water emerged from the plain bearing and drenched the tank vent. The engine smoked badly and I guess that the injectors had been ruined by water in the diesel.

 

Edited to complete a sentence.

Edited February 4, 2014 by mango

[cereal tiller]

 

I thought condensation was the major culprit.

 

MtB

Most canalboat tanks are built into the stern section,when temperature changes occur as in day/night, situations ,the air content of the tank will expand/contract.

 

each time the air in the tank contracts it will bring in moist air which condenses on the top and sides of the tank.

 

just one drop per 24 hours will build up to a detrimental amount

 

CT

[MtB]

I think this is a myth. If condensation was the major problem then all diesel tanks would have a layer of water at the bottom.

 

But all diesel tanks DO have a layer of water at the bottom!

 

This is why we have drain cocks at the base of diesel tanks, for getting it out. It's a common cause of domestic central heating oil boiler breakdown too. I was always draining water and shite out of oil tanks in gardens, even well-designed and obviously watertight ones.

 

 

Most canalboat tanks are built into the stern section,when temperature changes occur as in day/night, situations ,the air content of the tank will expand/contract.

 

each time the air in the tank contracts it will bring in moist air which condenses on the top and sides of the tank.

 

just one drop per 24 hours will build up to a detrimental amount

 

CT

 

Yep, this is the sequence of event I think causes the problem too.

 

Something similar happens with gas systems too, the ones with microscopic, otherwise undetectable leaks, when a boat is left with the gas OFF for weeks on end. Peeps may have noticed this on theirs. Come back to the boat and turn the gas ON, but the pilot lights won't light until air is purged from the system. How di it get there? Well after a week or two the gas pressure in the system falls to zero due to the microscopic leak. Then the temp cools at night and the gas pressure falls slightly below atmospheric pressure and a bit of air is sucked in over ten hours or so. Then the temp rises and the pressure rises, and a bit of the gas/air mix is expelled. Then next night a bit more air is sucked in and each time the cycle repeats, the gas in the pipe gets a little more diluted.

 

 

MtB

[ditchcrawler]

Most canalboat tanks are built into the stern section,when temperature changes occur as in day/night, situations ,the air content of the tank will expand/contract.

 

each time the air in the tank contracts it will bring in moist air which condenses on the top and sides of the tank.

 

just one drop per 24 hours will build up to a detrimental amount

 

CT

At the present time under the counter of our boat around the weed hatch and on the outside of the diesel tank is running wet with condensation so I wonder how much is forming on the inside of the top of the tank.

[mango]

 

But all diesel tanks DO have a layer of water at the bottom!

I think we will have to agree to differ on this one.

 

I do agree with you about the strange behaviour of gas systems. No smell of gas and leak-free according to a manometer. On one boat I put on the kettle for coffee before attempting to light the water heater, which ensures that the pilot light lights first time.