Removing sediment from bottom of fuel tank

akyaka

akyaka

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The heavy seas we have sailed in over the last few weeks has shaken up the 30 years of sediment in our fuel tank resulting in two engine failures. The tank is not large and whilst made of stainless steel is glassed in position.

Would appreciate any advice as to how to remove the crud with tank in situ. The boat is based in the Menai Straits.
 
I had a similar problem some years ago. Unfortunately, my tank is a keel tank, baffled, with quite a small access hole.

I rigged up a home-made “fuel polishing” system, with an old electric water pump, some plastic hose, and a fuel filter. First, I emptied the fuel tank. Then, for the best part of a day, I repeatedly tipped 25 litres of fuel back in and immediately pumped it out, from the bottom of the tank, through the filter, and into a plastic jerry can. For the suction pipe, I used a rigid plastic tube which I could move around the bottom of the tank, as far as the baffles allowed this. The action of quickly tipping 25 litres in stirred up the gunge in the bottom of the tank, and some of this lodged in the filter. I needed to change the filter element several times during the day.

Then I refilled the tank with clean fuel and triple-dosed it with Startron biocide. The real concern with any sort of gunge in the tank is that it will block the fuel filter and stop the engine (usually when you really need it). A buildup of ordinary dirt and grit in the filter tends not to be too much of a problem, because fuel can pass through it. On the other hand, dead “diesel bugs” leave a sticky slimy residue which can quickly coat the surface of the filter element and block it. Ordinary biocides won’t necessarily cure the problem. Startron, on the other hand, doesn’t just kill bugs, it contains enzymes which effectively eat up the slimy residue, leaving only “hard” remains which - like grit - won’t really block a fuel filter.
 
I opened the access hatch, dropped in a 12v submersible pump to transfer the fuel into jerrycans, then mopped up the sludge in the bottom with paper towels. Fuel was still suspect so gave it to a mate who runs big generators.

But I guess if you had such a handy hatch you wouldn't be asking the question ;)

Pete
 
Graham_Wright said:
Wickes wet and dry vacuum cleaner - £39! I has a great suck and I used mine to clean out the bilges. The attachments include a long hose and a long nozzle.
Click to expand...

Errr.. perhaps not a good idea. These vacs use the flow of extracted air to cool the electric motor. Although diesel fumes aren't hugely flammable, it could possibly lead to a fire. Best avoided!
 
The last tank I cleaned in situ, I removed a panel and crawled inside and round the baffles. Or is yours not that big?
 
With a similar problem I drained the tank in situ and used a pressure washer to clean the inside of the tank of left over residue. Getting the water out was easy and once a tankfull of diesel had been put in place the remaining few drops were skimmed out naturally by the fuel polisher I built ( fuel pump, separator and filter ).
 
pvb said:
Errr.. perhaps not a good idea. These vacs use the flow of extracted air to cool the electric motor. Although diesel fumes aren't hugely flammable, it could possibly lead to a fire. Best avoided!
Click to expand...

Geroff!!!!!:)

It worked great for me but it did cause some aeration. If you're chucking away the contents, it matters not otherwise it takes a while for the bubbles to settle.
 
I bought a Wolf pump which looked very much like a small plastic copy of the raw water pump on your boat complete with flange to mount it and push / click in and out connections for typical garden hose. I mounted the pump on a board together with a 12v electric drill to power it. Shifted 50 gals of diesel and any crud it found in just 10 minutes or so with most of the time spent changing over 5 gallon jerry cans. Worked well

Problem was the tank was installed before the deck and the access was only at one end with two other large sections hidden behind baffles. In retrospect I probably should have reversed the pump and hosed the bottom of the tank with diesel to loosen the crud.
 
>A vacuum cleaner will never light diesel. Ever tried lighting it with a flame?

You might be right but I wouldn't risk it. Diesel spray will explode obviously. Put another way the professional tank cleaners don't use that method.
 
PCUK said:
A vacuum cleaner will never light diesel. Ever tried lighting it with a flame?
Wet and dry vacuum every time.
Click to expand...

Should you ever attempt this please issue a NTM before those those of us with common sense can move our vessels as far away from you as possible.:D:eek:
 
Lots of food for thought .thanks. The only access is through the filler pipe nor is there access for one to be cut in the top. The crud is the accumulation of many years of filling from bowsers on the beach.No more as being a small tank( 10 gallon) we do not now use red diesel.
 
If the filler tube is wide enough, you may be able to poke a pressure washer nozzle down it once the fuel has been drained, then suck the crud and water out with the wet & dry vac.
 
This is what might be at the bottom :eek:
Tank1.jpg

After emptying out my tank, through the inspection hatch, and steam cleaning it looked like this :)
Tank2.jpg

In the absence of an inspection hatch you probably need to pressure wash "blind" down the fuel inlet to loosen it, then suckout, then repeat until you think it is clean.
Can you get some form of "endoscope" to inspect it internally?
 
aquaplane said:
The flash point of diesel is >62°C so using a wet/dry vac is not going to go BOOM unless it's a VERY warm day.
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what about when the vac tips or is overfilled?

it certainly will vapourise,(you can guess how I know) hopefully the sparks from the brushes wont light it.

wet vac is graet for lifting the sludge if you can get the nozzle round on the tank bottom.
my suggestion would be to remove fuel

add 2 gall of hot deterganty water

agitate by pump, rocking & any other method.

remove , rinse fill with water and 2 bottles of bleach to kill any remaing live bug, hopefully.
pump out and dry, with the outlet pipe from the wet vac, as air will be warmed by motor.
 
My penny's worth. I not saying it right or wrong.

Wet or dry vacuums have a bi pass motor.

The motor is cooled via it's own fan,, not the pick up hose end (working air)

The machines have two separate compartments so motor cooling air doesn't come in contact with the working air.
 
capetown said:
My penny's worth. I not saying it right or wrong.

Wet or dry vacuums have a bi pass motor.

The motor is cooled via it's own fan,, not the pick up hose end (working air)

The machines have two separate compartments so motor cooling air doesn't come in contact with the working air.
Click to expand...

Some might; not all do.
 
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