Clean diesel tank with no access hatch (or easy access)

[alisdair4]

I have just discovered that my 25 gal, stainless steel diesel tank has a serious case of diesel bug/water in the fuel. It seems a pretty bad case - the primary (bowl) filter and the engine filter was changed, the fuel system bled and the engine was running fine just after the New Year holiday. I added more biocide and topped the tank up to the brim. 10 days later, I attempted to start the engine without success and, on checking the bowl filter, there is about 1cm water at the bottom.

On speaking to my friendly mechanic, his advice was to drain the tank completely, then clean the gunk out of the tank - ideally with steam. Unlike other vessels mentioned in similar threads here, there is very limited access to the tank - and no inspection hatch. As far as i can see, the tank was put in before the deck went on (30-odd years ago...)! I can reach it with one hand, via an access hatch in a quarter berth. (There are no Hobbits on the Island)!

The tank has a fuel take-off at the bottom; a fuel return inlet at the top, and a filler (45mm) neck at the top.

I think I can get the old fuel out - and, possibly suck all of the water out. How would I get rid of the gunk?

 

[rogerthebodger]

IMHO if you don't has a access hatch that you can clean/check the inside of your diesel you should fit one.

There has been a discussion on fitting an access hatch here

http://www.ybw.com/forums/showthrea...o-stainless-diesel-tank&p=5575408#post5575408

 

[pvb]

Without access, it's difficult to do it well. But you can achieve something by doing some fuel polishing. You need to rig up a fuel pump connected to a fuel filter, then circulate the fuel through it constantly. I used an old electric water pump, to get a decent throughflow. If you use a rigid suction pipe, you can bend it to enable you to suck up the rubbish over an area of the tank bottom, although baffles may make this difficult. you may be able to use the returning fuel to stir up the rubbish - again, a rigid pipe helps direct it to the right places. As the rubbish gets removed, the filter will clog and will have to be replaced. For this reason, cheap filters are preferable, so maybe use a simple CAV296 type filter rather than a Racor! I used this method with a 150 litre keel tank, under the engine, with terrible access, and succeeded in getting most of the bug rubbish out. Good luck!

 

[alisdair4]

IMHO if you don't has a access hatch that you can clean/check the inside of your diesel you should fit one.

There has been a discussion on fitting an access hatch here

http://www.ybw.com/forums/showthrea...o-stainless-diesel-tank&p=5575408#post5575408

Yes, I did see this post, among others. I cannot see how I could fit a hatch when I can only get one hand into the space where the tank is fitted. Another option may be to cut the old tank up in situ, and replace it with a smaller tank, perhaps elsewhere in the boat. There isn't much space in a Rival 32..!

 

[alisdair4]

Thanks for that. Would it be simplistic of me to assume that I could rescue the majority of the fuel by sucking it out with a Pela pump and decanting it into cans - or is the bug throughout the contents of the tank? I don't mind losing the bottom 2-3 gallons as long as it gets the gunk out. I could use your method to polish the rescued fuel, if need be?

 

[pvb]

Thanks for that. Would it be simplistic of me to assume that I could rescue the majority of the fuel by sucking it out with a Pela pump and decanting it into cans - or is the bug throughout the contents of the tank? I don't mind losing the bottom 2-3 gallons as long as it gets the gunk out. I could use your method to polish the rescued fuel, if need be?

You can certainly suck out most of the fuel, put it in containers and leave it to settle for a time (no need to polish), then suck out the clear stuff into clean containers for re-use. When you eventually return it to the tank, double-dose it with biocide (Marine 16 is not bad).

 

[chrishelen]

Hi I had a similar problem two years ago, the bug would clog the cav filter almost straight away if the fuel got stirred up. Access to the tank was almost non existent. I managed to suck all the fuel out with a syphon and decant into 25 ltr containers, it was pretty dirty with slime and bits of black stuff floating around, I then managed to get a wet vacuum cleaner pipe into the fuel filler pipe and sucked up the residue, I don't think I got all of it, but I think the worse jf the sludge was sucked out. Then I poured the dirty fuel into a clean container through a funnel filter which took all the crap out, it took all day to do about 60 ltr but at the end I had cherry Red fuel ready to go back in, I then dosed up the tank with poison and touch wood, all is well, I change the primary at 250 hrs and so far it has been clear.

 

[alisdair4]

Chris,

thanks for that- really encouraging! I was starting to consider major surgery and lots of £ signs!

 

[Poignard]

I steam cleaned my 12 gallon diesel tank using a hired wallpaper stripper. As I remember, it took about 12 to 16 hours until no more black stuff came out. BUT I was able to remove the tank so this allowed me to move it into different positions as I steamed it. As you aren't able to remove the tank you might not get as good a result as I was able to. Even so, it might be worth you trying it. It doesn't cost much to hire the wallpaper stripper.

 

[alisdair4]

I'll hold that thought- thanks! Step 1 is to get the diesel out of the tank. ��

 

[William_H]

Yes the pella suction type pump is best approach. Suck out as much as you can after draining from the normal fuel take off.
You may be able to put some list on the boat for a long period so that gunk settles to one side or corner.
As said put it into containers and allow to stand for 24hrs then decant off the top layers of clean fuel. Glass jars are handy here if you can find jars big enough.
If you had a pump that delivers some pressure you might then blast clean fuel into the corners as far as possible then suck out again before the gunk settles.
Ultimately with no access hatch and without removing the tank you will just have to persevere with this cleaning until you seem to be sucking out clean fuel after blasting in fuel to clean it, and until you reckon you have done enough.
Then use biocide and and keep spare filters on hand for change when at sea.
I don't believe fuel polishing alone will get all the settled gunk in the corners. good luck olewill

 

[Fascadale]

I see that the OP's boat is a Rival 32

It may be worth him contacting Ian Nicolson, the surveyor and guru of all thing Rival.

I understand that Ian, when faced with the same problem on his R34, cut a hole in the cockpit floor thus giving access to the top of the tank where he then fitted an inspection hatch.

 

[vyv_cox]

Thanks for that. Would it be simplistic of me to assume that I could rescue the majority of the fuel by sucking it out with a Pela pump and decanting it into cans - or is the bug throughout the contents of the tank? I don't mind losing the bottom 2-3 gallons as long as it gets the gunk out. I could use your method to polish the rescued fuel, if need be?

I drained my tank through the discharge tap at the bottom. I could only fit fairly small containers beneath it but did the job when the tank was run well down. However, with a full tank, no reason why you could not siphon most of yours out first, the simple plastic manual siphon pumps will do it well provided the tank is relatively high in the boat, otherwise buy a cheap electric pump on Ebay, there are plenty on sale. I then pressure washed the tank to stir up the sediment as I had no access to steam cleaners. I was able to remove my tank but no reason why the same method would not work in situ.

 

[lw395]

I have just discovered that my 25 gal, stainless steel diesel tank has a serious case of diesel bug/water in the fuel. It seems a pretty bad case - the primary (bowl) filter and the engine filter was changed, the fuel system bled and the engine was running fine just after the New Year holiday. I added more biocide and topped the tank up to the brim. 10 days later, I attempted to start the engine without success and, on checking the bowl filter, there is about 1cm water at the bottom.

On speaking to my friendly mechanic, his advice was to drain the tank completely, then clean the gunk out of the tank - ideally with steam. Unlike other vessels mentioned in similar threads here, there is very limited access to the tank - and no inspection hatch. As far as i can see, the tank was put in before the deck went on (30-odd years ago...)! I can reach it with one hand, via an access hatch in a quarter berth. (There are no Hobbits on the Island)!

The tank has a fuel take-off at the bottom; a fuel return inlet at the top, and a filler (45mm) neck at the top.

I think I can get the old fuel out - and, possibly suck all of the water out. How would I get rid of the gunk?

I don't think a hatch is imperative, after all your tank has done 30 years without disaster.
There are lots of cheap camera systems you can shove down the filler pipe these days if you really want to look inside.
What you really want is a means of keeping the tank as water-free as possible, like a standpipe that draws from the lowest point.
If there is a lot of gunge sticking to the tank, steam cleaning is best.
Otherwise you can normally just suck the crud from the bottom of the tank and filter the diesel you take out.

 

[MagicalArmchair]

I have a similar situation, as part of my refit I wanted to clean out the tank and only have access through the sender hole. As others have suggested, I PELAed out the diesel and ran it through one of these filters:

http://www.seamarknunn.com/acatalog/water-blocker-funnel-large-1651.html

I now have an empty tank and some clean fuel, just need to clean the skum out. I am planning on doing that with fish tank cleaning stuff.

If I can't get it adequately clean, I'll cut the access hatch - I'd prefer to avoid if I can!

 

[lw395]

I have a similar situation, as part of my refit I wanted to clean out the tank and only have access through the sender hole. As others have suggested, I PELAed out the diesel and ran it through one of these filters:

http://www.seamarknunn.com/acatalog/water-blocker-funnel-large-1651.html

I now have an empty tank and some clean fuel, just need to clean the skum out. I am planning on doing that with fish tank cleaning stuff.

If I can't get it adequately clean, I'll cut the access hatch - I'd prefer to avoid if I can!

That does not look too badly stuck on.
I'd have suggested agitating the diesel to remove it, I used a flail made from a bit of rope on the end of a rod, spun in a drill.
But now the diesel is out, I'd suggest using a hose from a wallpaper steamer.
Or a jetwasher would do it.

 

[alisdair4]

Thanks all. I am aware of Ian Nicolson's writings - interesting stuff. However, I still baulk at the option of cutting a hole in the cockpit sole. I will persevere with the methods covered in this thread.

 

[vyv_cox]

A Pela is a very useful bit of kit but emptying a 100 litre tank with one seems like a tedious job.

 

[lw395]

A Pela is a very useful bit of kit but emptying a 100 litre tank with one seems like a tedious job.

Yes it would be.
But generally you only need to take a few litres from the bottom of the tank.

 

[alisdair4]

Yes it would be.
But generally you only need to take a few litres from the bottom of the tank.

But would one not need to filter or polish all of the fuel that had been in the tank? That is why I am planing to pump out most of of the contents via the filler hose, let it settle and then filter it. Or is this step not needed?