Diesel Fuel Tank Cleaning

[Midnightsun]

I have a small issue I think. I believe I have some water in the bottom of my main tanks. Reason I say this is my boat is equipped with a diesel heater which I never really got to work. I pulled it out last year and rebuilt it but still it does not function properly. Played with it for the last couple of days and noticed lots of water in the line therefor giving me a no start fault. Primed the lines until all was clear and then she fired up and ran like a champ for a few hours before I shut her off. Last night I decided to try her out, she started up fine but a few minutes later she conked out and once again a no start fault.

The filter is transparent so I can see there is once again water in there. My Racor main engine filters hardly see any water by the end of the year, in fact I just emptied them yesterday, maybe 1/4 ounce total for both.

Theory, my heater draws from a very small 2mm ID diameter copper fuel line inserted from the top of my starboard tank. I am thinking this tube is inserted almost to the bottom and therefor can suck up water in the tank. I am going to try to loosen the retaining nut and pull up the intake a couple inches to see if it solves my heater water problem however this would indicate I do have a little water in the tank/s

Question, is this normal to have a little in there or should I be looking at getting this out of the tanks. If so, how is this done?

[bud37]

Hans , if you have access then perhaps you can vacuum the tank bottoms with one of those Pela oil change tanks...that way you will see what comes out. Will work if there is a straight shot down thru the fillers as well.

[Midnightsun]

Great minds think alike, had that in the back of my mind.

[Hugo]

You don't want water in there. Our tanks are aluminum and that will cause corrosion on the inside of the tank. Biological growth in tanks also need water. My tanks have extra plugs for pick up tubes so I stick a copper pipe with a hose over it hooked up to a pump. You need boat out of water bow up and access to the rear of the tank closer to the stern. Ideally I'd want a drain under the tank but I think regulations don't allow that.

[Midnightsun]

Thanks for the insight. I do believe a little water is OK however it may have more than a little. Boat is now on the hard so I will see what access I have towards the rear of the tank. I think there is an additive that emusifies water so it can be burned up during regulat use as opposed to acumulating in the tank bottom. May look into this for as regular additive once I have removed as much water as possible.

Here is a very explanatory article regarding diesel/water. https://www.ezoil.com/resources-diesel- ... sification

[Hugo]

I wonder how much of that emulsified water will go through the injection pump and injectors? Wouldn't be good if it did...
Maybe we need to test with a pump and a racor to see if the racor actually pulls all the emulsified water out or if some gets through.

That article was good but if it were me I would mechanically remove the water (if possible) and not add any additives.

Good luck!

[Viper]

Water is not very friendly to injectors especially in a diesel application because of higher fuel and cylinder pressures. Have seen injector tips ruined because of it.

Additives have a place but it's best to try and prevent getting water in the first place though I'll admit that's not easy. They also have their limits which is dependent on the amount of water in the tank, there has to be a saturation point, and how long do the additives keep the water in suspension?

I think you're on the right track, remove as much water from the bottom of the tank as possible. Since you probably won't get it all, treat the fuel and hopefully the amount of water left will be caught in the primaries or burned without causing any issues.

[Midnightsun]

I have done some research on this and yes have come up with the injector issue. The problem I now fear is using any kind of water emulsifier as it may break the water down to smaller particles than the primary or secondary filters are able to deal with so still on the fence with the emulsifier thing. Good news is the Volvo secondary has a sensor for water contamination which has never gone off yet. Running 20micron primaries and I am pretty sure the secondaries are 10 micron.

Anyone here with D series Volvos, this video shows the water sensor and how to prime the fuel system in case you did not know. I suggest you keep a small length of 1/4" ID hose on board to attach to the primer nipple instead of squirting fuel all over the place.

[Viper]

Don't know that I agree with the statement of never putting fuel in a filter prior to installation. IMO, the comment should have included that it's okay to do that only if it's a mechanical fuel pump application. In the context of this video it's okay but it's too general a statement. You should never install a fuel filter on an electric pump application without filling it first. The fuel is what lubricates an electric pump and running it dry until the filter fills up will shorten the pump's life. Water doesn't help here either.

[Midnightsun]

I install dry HOWEVER, you simply unscrew the bleeder valve and pump the primer until fuel comes out, which comes from the primary from the tank, it is now full.

I find this primer quite practical as when I change my generator filter I simply attach the hose to the nipple on the secondary unit and insert the other end into the Racor spin on genny filter with sediment/water bowl attached. I pump until the filter is full and then screw the generator filter back into place. I can also use it to fill a small container to fill my primary main engine filters when changing filter elements.

I realize a true mechanics shop is set up with diesel and means to pour pump it into filters however for me as a DIY guy this method avoids bringing diesel and containers with me to the boat. Also I would need to go to the gas station and get a gollon of diesel which I may not use entirely and then I need to dispose of this. Not very convenient as not many people have diesel in jerry cans at home. Gas, no problem as almost everyone has this in the shed.