Diesel Fuel Tank deposits/sludge/tar

[richardsussex]

Have a stainless steel tank on 5-year old boat. Only access is hole for fuel sender unit.

I am getting a bit of sludge forming in the bottom of the tank, It's a black tarry mess – slightly gritty - and is now a couple of mm deep (it has got worse over the past year). From reading the threads on here I know a lot of yotties have this problem, but what's the best way of getting rid of it, or stopping it getting worse?

My marina has access to a pump for "fuel polishing" (presumably for filtering out mould and dirt) but how do you get rid of the tar? A vacuum pipe isn’t much help as tank has internal baffles. I have looked on the net and there are some things mentioned like Exocet and Soltron. I have only the fuel gauge aperture as access. And it's a big tank.

The general impression I am getting is that diesel is an unstable fuel and its quality has got worse over the years, and that at least road diesel is reported to have been getting more additivies to prevent deposits. No mention of the same thing happening to red diesel. Even if I changed to yellow diesel tomorrow I still have sludge in my tank which is a worry to me next time I go out in a reasonable chop.

Have used Grotamar71 fuel additive (Best buy in more than one ybw test) since new and the fuel is clean and clear. No mould. Filters not getting clogged up.

What I need is some sort of solvent that will dissolve the tar and leave it in suspension to be pumped out. I would reduce level of fuel in tank as far as I could, put in said product and then pump tank dry and dispose of the dirty fuel, and then replace the good stuff.

All comments and suggestions gratefully received. Thanks

 

[David2452]

Petrol? Acetone?

I imagine almost any solvent would still need some kind of "agitation" to get the tar in suspension.

 

[pcatterall]

I'm lucky, my 2x50gallon tanks have large access covers.
Is it possible ( worth while) creating an access cover? bit of a pain but handy once done?
I have made up my own version of a fuel polishing kit. I use it when transferring fuel from the reserve to main tank.
The pipes go right down to the tank tank bottom so a couple of times a year I can remove the bottom 3 or 4 gallons ( the really mucky accumulation) and pass it a few times through the polisher. I can stir the bottom with SWIMBOS long handled dish scrubber.
I dont know if there are chemicals which will get your sticky sludge into suspension.
Short of re-creating choppy sea conditions I cant think how to replicate the conditions which will stir the mess up for you.

 

[starfire]

Without access it's difficult.

An access cover is the way to go.

Otherwise I would suggest 2 possible ways, you also have access via the filler pipe ?

1. Using the fuel polishing kit, create a long wand out of copper pipe with a flattened end to create a spray, use this on the outlet of the polishing rig through whatever access you have, to 'pressure wash' the bottom of the tank.

2. Get a steam cleaner, drain all the fuel from the tank, steam clean as much as you can.

Pump the tank dry, use acetone to mop up the remaining water & dispose of the mess.

Both work better if you can arrange a temporary fuel supply for the engine, then you can go for a sail to agitate the tank.

 

[rich]

I could tell you what to use,but some folks on here. get upset when I say the S word.

 

[nimbusgb]

You have diesel bug.

Fortunately you have access to a polisher, arrange to use it.

Beg, borrow or purchase an oil suction pump ( Pela or similar - fit with a 5mm or greater bore suction pipe ) to remove the worst of the 'tar' then hook up the polisher and let it run for a day or so, circulating the fuel as much as possible. Agitation may be required ( A length of 7*19 stainless cable in a batterey operated drill will get through baffle holes )

Buy lots of filters for the polisher.

Replace any filters in your fuel system with new ones.

Treat a tankful of fuel with your preferred anti-bug solution.

 

[richardsussex]

Thank you everyone

Much appreciate all of your ideas and suggestions.

I agree that an access aperture would be the best way forward but as you can see the amount of tank visible is very small and trying to drill on the side of the tank (even if I wanted to) isn't possible either.

btw, I didn't know that I had "diesel bug" - I thought that this was a mould that grew where water rested on top of the fuel... and my fuel definitely looks clean and clear. Grotamar warn against exceeding the maximum dose for their additive as it "may cause deposits". So it's difficult to know where I have gone wrong. Except that the general feeling seems to be that diesel is an unstable fuel.

So, I shall start using my generator tank as a "day tank", will pump out as much fuel as I can from main tank, add some petrol, take the boat out and get the fuel moving around and see if the deposit loosens up. Then is will be a case of pumping out the residue, assisted by a fuel polisher.

Have also emailed Grotamar UK "Contact Us" to see if they have any suggestions but I doubt whether they will be that interested as they seem to deal mostly with commercial ships and refineries etc.

Anyway, thanks again to all of you for kindly taking time to reply and a Happy New Year

Fair winds etc

 

[FuelRepair]

Richard, has this problem arisen since?

 

[CaptainBob]

We're going through the same thing after finding out the hard way with an engine failure due to blocked filters. We also used Grotamar (in our case after reading that it was the best in one of the sailing magazines).

I won't bore you with our protracted story but we now have a Racor Duplex filter installed so we can monitor the clogged-up-ness (it has a gauge) and if required, very easily hot swap filters. This has solved our problem and gives us much peace of mind about emergency filter changes in sticky situations in the future. Expensive though!

Subsequently have heard from more than one that Grotamar has caused quite a few others to have problems with blocked filters as it creates a lot of solids. Have not heard the same about Fuel Doctor, which is generally recommended down Dartmouth way.

 

[Piers]

Have a stainless steel tank on 5-year old boat. Only access is hole for fuel sender unit.

I am getting a bit of sludge forming in the bottom of the tank, It's a black tarry mess – slightly gritty - and is now a couple of mm deep (it has got worse over the past year). From reading the threads on here I know a lot of yotties have this problem, but what's the best way of getting rid of it, or stopping it getting worse?

My marina has access to a pump for "fuel polishing" (presumably for filtering out mould and dirt) but how do you get rid of the tar? A vacuum pipe isn’t much help as tank has internal baffles. I have looked on the net and there are some things mentioned like Exocet and Soltron. I have only the fuel gauge aperture as access. And it's a big tank.

The general impression I am getting is that diesel is an unstable fuel and its quality has got worse over the years, and that at least road diesel is reported to have been getting more additivies to prevent deposits. No mention of the same thing happening to red diesel. Even if I changed to yellow diesel tomorrow I still have sludge in my tank which is a worry to me next time I go out in a reasonable chop.

Have used Grotamar71 fuel additive (Best buy in more than one ybw test) since new and the fuel is clean and clear. No mould. Filters not getting clogged up.

What I need is some sort of solvent that will dissolve the tar and leave it in suspension to be pumped out. I would reduce level of fuel in tank as far as I could, put in said product and then pump tank dry and dispose of the dirty fuel, and then replace the good stuff.

All comments and suggestions gratefully received. Thanks

Grotomar is excellent and may well start to dissolve the muck you talk about, over time. The expert on this is Bandit from Guernsey of this parish. He deals with many boaters who have fuel issues and sorts them out.

 

[chewi]

Admittedly this won't help unless you can take the tank out of the boat, but with mine we threw a handful of mildsteel M8 nuts in the bottom and shook the hell out of the tank, alowing the nuts to dislodge the sludge , then pump out. A magnet rerieved them from the s/s tank.