Sea water in diesel tank

[cmedsailor]

I have accidentally put some sea water in the diesel tank (probably maximum one glass, say a quarter of a liter) and then made the mistake to run the engine for around 10 minutes thinking that the water/diesel separator filter (racor) may catch it. No water appear in the racor and the engine run fine by the way.
What shall i do? Do you think what i did (running the engine) could have caused any damage? Shall i just drain the whole tank (has around 60lt) replace the filters, empty any diesel in the racor and then add clean diesel?
Thanks

 

[Aeolus]

The water will probably be sitting in the bottom of your tank below the outlet, so unlikely to be sucked into the engine until you're out at sea and the motion causes the water to get mixed up with the diesel.

If you can drain from the bottom of the tank, then the water should come out first.

 

[pmagowan]

I wouldn't worry too much. I have had well more water than that in my tank with no problems. The Racor is excellent and it will settle in the trap and can be let out. It will sink to the bottom of the tank so will only come through in dribs and drabs when the tank is tossed about. You can get additives that supposedly absorb water but I don't understand how. If you have a sump to your tank you could stick a hose down and suck it out but with such a small amount I don't think it is a big deal. Others may disagree.

 

[knuterikt]

I have accidentally put some sea water in the diesel tank (probably maximum one glass, say a quarter of a liter) and then made the mistake to run the engine for around 10 minutes thinking that the water/diesel separator filter (racor) may catch it. No water appear in the racor and the engine run fine by the way.
What shall i do? Do you think what i did (running the engine) could have caused any damage? Shall i just drain the whole tank (has around 60lt) replace the filters, empty any diesel in the racor and then add clean diesel?
Thanks

The water have probably settled below the level of the suction pipe going to the fuel filter.
It can become a problem when motoring i waves.

If you don't have a drain at the bottom of the tank you insert a small hose going to the bottom of the tank and pump it out.
On my boat we have a access port at the top of the tank we use for inspection and pumping out.
If you don't have a assess port in the tank you might have a tank sensor you can take out.
Last option would be to go down through the filling cap.

I have vacuum extractor like this I use for this type of things

 

[NorthUp]

If you have a vacuum type oil extractor you may be able to 'hoover' the bottom of the tank.
As above though, there was probably water in there anyway.

edit, beat me to it!

 

[cmedsailor]

If you don't have a assess port in the tank you might have a tank sensor you can take [/img]

Unfortunately that's my only option. I have never removed it in the past so hopefully i will manage without breaking anything...
I guess remove the four screws and pull up to remove?

 

[knuterikt]

Unfortunately that's my only option. I have never removed it in the past so hopefully i will manage without breaking anything...
I guess remove the four screws and pull up to remove?

Yes just be careful when you lift it out so you don't bend the float arm.

The good news is that the sensor sits close to the deepest part of the tank

If you use a clean container to collect the fuel/water you will also get good indication if there are other "fun" stuff in the tank.
Keep pumping until you get clean fuel and then some more.

 

[KenMcCulloch]

As it happens I have just spent a happy Friday working on our boat's fuel supply. I assembled this simple polishing rig

out of standard bits (the electric pump was about £17 from an ebay supplier). The suction hose is partly copper for stiffness to allow it to be directed to every accessible corner of the tank and by running it for 3 hours we have in theory filtered every ml of diesel at least twice. The priming bulb is there to prime the system and allow the filter to be bled. A truly PBO solution to the dirty/water in diesel problem, I think.

 

[Deleted member 36384]

Ken - Let it settle and repeat the clean up again. The small amount of head and small diameter pipes (inlet an outlet) will only draw down fuel form a small radius around it. Even if you move the bits around a lot you are not likely to filter all the fuel in one go even though the pump may have circulated multiples of the whole volume.

 

[NormanS]

It all makes you wonder why modern tanks are not made with sumps. My fuel tanks have a small sump at the bottom. Any movement of the boat encourages any dirt or water to gravitate into the sump. The bottom of the sump has a drain valve. I use it periodically. Problem solved.

 

[PabloPicasso]

Ok I'll start a new thread on home built fuel polishing

 

[claudio]

You will probably get more water in your tank when you fill from the pumps unless you use a water separator funnel. Most filling station diesel tanks never get cleaned properly.

I wouldn't worry too much, the Racor will catch it, just keep an eye on the water level in the filter, and just keep emptying the water, some have water level alarms.

 

[KenMcCulloch]

Ken - Let it settle and repeat the clean up again. The small amount of head and small diameter pipes (inlet an outlet) will only draw down fuel form a small radius around it. Even if you move the bits around a lot you are not likely to filter all the fuel in one go even though the pump may have circulated multiples of the whole volume.

I'm sure you are right. The plan is to do it every time the tank gets down to half full or less, if possible. Using the transparent hoses did enable us to see how much crud was coming through and the size and frequency had declined markedly by the start of the third hour. It may not have got every bit of crud out but we have made a difference. The main intention was to try to make sure that large lumps, such as that which blocked the feed entirely and caused engine failure a couple of months ago, are eliminated. Small bits that can pass through the pipes are not really a problem so long as the filter is changed reasonably regularly.