# Water in (diesel) fuel - removing



## camallison (Jul 15, 2009)

I am aware that I have traces of water in the diesel in my MH. To remove the water from the fuel filter I have been told to open the little "tap" on the bottom of the filter. Now I am a cautious soul, and don't wish to introduce air into the fuel lines. So, my questions is this, can I just open the "tap" and drain off the offending water, or should I do it with the engine running to keep a constant head of fuel?

Colin


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## BillCreer (Jan 23, 2010)

There are traces of water in all diesel so don't worry about it. 
Just drain the filter on a regular basis without the engine running. The fuel pump will self prime and fill the filter. On some older engines you might have a rubber prime button or bulb to squeeze to speed up the process.


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## camallison (Jul 15, 2009)

Onto it now Bill - thanks for your very prompt response.

Colin


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## Glandwr (Jun 12, 2006)

Don't mean to hi jack your thread Colin but I'd like to ask Colin a question. I've gone back to diesel after a long way away. In the olden days if I ran out of fuel it was a case of bleeding the system to get going again.

I’m still paranoid as the needle gets to the end today. I’ve got two vehicles a car and MH (BM and Sprinter) both ‘54 plates. Would these now be self bleeding or should I continue to be paranoid?

Dick


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## camallison (Jul 15, 2009)

Not sure Dick - I am as much in the dark as you - maybe Bill can answer that one. Our van has a 2007 Renault Master base vehicle and the fuel system on that has the "squeezy bulb" that Bill refers to.

Colin


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## Glandwr (Jun 12, 2006)

Sorry Colin it was Bill I was asking. My mistake (I put it down to the hot weather)

Dick


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## BillCreer (Jan 23, 2010)

I think you have to assume that if you run out of fuel and there is no priming pump then the system will self prime.
After running out of fuel the first job to do would be drain the filter.
The priming pumps are usually used after you have changed the filter. If you can drain the pump it's almost as easy to change the filter, just make sure you don't allow any dirt in.


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## BillCreer (Jan 23, 2010)

I once pumped 8 gallons out of my Citroen BX tank with the "Bulb" after I mixed 8 gallons of petrol into 4 gallons of diesel. Surprisingly it did drive the mile home with that 2:1 mixture where I pumped 8 galls of 2:1 out and filled it up with diesel. Ran ok after that. 
The tank was too low to siphon so the bulb was very handy but hard work.
I’m not sure if I would if I would get away with it on new diesels that have computer management but a limited amount of petrol does mix quite happily with diesel. Just don’t put diesel in you petrol vehicle.
Ramble over


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## sideways (Jun 2, 2008)

Gladwr, be careful not to run your Sprinter out of fuel, the fuel pumps only source of lubrication is the diesel its pumping.I hired a Sprinter that had a large warning sticker on the dash warning of dire consequences of running it out of fuel.


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## grizzlyj (Oct 14, 2008)

Hi

Just as an aside, I believe many (all?) diesel systems have a flow and return, so any fuel unused by the engine goes back to the tank. My fuel pump for instance runs flat out all the time, so there is a large amount of fuel going back to the tank from the hot engine.

This means that after a long drive the contents of your diesel tank will be warmer than the air around it. The air in your tank will also be warm, and as it cools the water vapour naturally in it condenses on the tank walls, running into the diesel.

This will happen all the time, on every vehicle, so must be something the fuel system can cope with.

I've been told that good practice, however, is to always aim to fill the tank at the end of the day. as this will minimise the air volume during the overnight cooling, and therefore the water available to condense out.

Jason



Theres also a product called Mr Funnel used in the UK by gokarters and microlightests that will filter the fuel. The largest size is not widely available, but it will remove water from diesel for you if you felt inclined or had a problem that required you to.


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## tony50 (Oct 16, 2007)

camallison said:


> I am aware that I have traces of water in the diesel in my MH. To remove the water from the fuel filter I have been told to open the little "tap" on the bottom of the filter. Now I am a cautious soul, and don't wish to introduce air into the fuel lines. So, my questions is this, can I just open the "tap" and drain off the offending water, or should I do it with the engine running to keep a constant head of fuel?
> 
> Colin


My advice is to drain the fuel filter before you start it after say overnight that way you won't have stirred the fuel and water up in the filter housing , you only want to drain it for a few seconds (should start up ok ) ,unless you have substantial water in the system , then it's advisable to drain it if it has a drain plug , or remove tank and swill it out with diesel and then change the fuel filter a couple of times .

Tony A.


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## Chausson (Oct 17, 2006)

Hi
Modern diesel engines do NOT like running out of fuel it can be very costly if you have to call out a MB mechanic, so keep it at least quarter full all the time then you're OK.


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## buffallobill (Sep 28, 2007)

when my water in diesel light came on .dash board i followed instruction of hand book ,
that was to unscew the drain at the bottom of the filter. this drain plug also had the electric wires attached to it for the water in diesel sensor.
i did what the book said with the engine switched off.
caught the diesel/water in small container,
it only comes out slow.
replaced the drain plug/ sensor and the engine fired up ok.
engine is a fiat 2.5D 1998 model.


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