it's time to replace the fuel tank...

S

Shearwater

Well-Known Member
Joined
19 Oct 2005
Messages
428
Location
Felixstowe Suffolk UK
Visit site
it\'s time to replace the fuel tank...

I have started working on a 1982 motor boat powered by a Perkins 4108 diesel, based Spain (i.e. hotter than UK climate), and in general, poorly maintained. I haven't had a diesel inboard before but am aware of diesel bug and and the probability of sludge in the tank so am going for a new, plastic fuel tank; the question is whether to try installing it myself or leave it to the boatyard. I've found various 50 to 70 litre plastic tanks but, as yet, haven't found where to get the pipeline connecting thingies, outwards and return. Does the team think working in a confined space (oh, it's going to hit 23 degrees tomorrow), sawing or angle-grinding an old (GRP?) tank full of grot, crud, slime and probably maggots and then clearing up the mess is worthwhile? The bilges, btw, are greasy, grimy and stinking. If I ask the boatyard to quote, is there anything I should specify particularly (i.e. a water separator or new pipelines or....?). Tips, comments welcomed; guffaws ignored !
Why did I buy it? Well the hull is in vgc with only a little osmosis, the owner had to sell as he's quitting Spain and I got it cheaply enough to permit a budget for the refurb. Oh, and I like the shape of the hull, it's very traditional.
 
Re: it\'s time to replace the fuel tank...

It's the "try" that worries me; if it isn't totally cleared of muck then surely that muck is freed up to go down the fuel line and cause problems. And what do you use to clean out the tank? More diesel?
 
Re: it\'s time to replace the fuel tank...

The place for plastic tanks and fittings TekTanks see:- http://www.tek-tanks.com/ They also do custom tanks to suit your space. Does the tank have an inspection hatch which you can get inside to all the corners etc? If so it can be cleaned , I suspect just by mopping up all the old diesel and washing it out diesel? or perhaps some sort of cleaning gunk - others may be able to advise - how about Bilge cleaner? I;ve use this for cleaning oily bilges and it was successful. If you don't have an inspection hatch, cut one out then use a stainless plate or something similar to make a cover.
 
Re: it\'s time to replace the fuel tank...

I've just cleaned up and re-used my old tank (from 1960's) although it was petrol so I didn't have the same worry of bugs as you.
I've cut an inspection hatch in the top to give pleanty of acess to clean inside and coated it with tank sealer to prevent any build up of gunk inside.
It saved me a fair bit off the cost of replacing plus I had a tank that fitted the boat rather than the standard rectangular ones you can buy.
 
Re: it\'s time to replace the fuel tank...

Cleaning out the tank would be my choice. Suck the fuel out, pass fuel through a filter then blast fuel back into the tank so that the content of the tank is well mixed up. Repeat process until fuel is seen to be clean. Of course, getting in to suck and blow could be difficult but this process should be more economical than changing the tank.
 
Re: it\'s time to replace the fuel tank...

If you can access the tank, and most had hatches, bail the diesel into drums for re-use, and go through your's, your wife's, your friend's wardrobes for all the old (clean) underpants, shirts, tee-shirts, sheets, towels etc you can lay your hands on. Buy some Marigolds 'cos 'err at 'ome won't let you beyond smelling range otherwise, and mop the bugger out and dump all your old rags into a bin bag. If you can get hold of some acetone that's good for a final mop and clean and engines don't mind a bit of that anyway. Better job and far cheaper than new tanks and a whole lot less effort. Besides, with a decent inspection lamp you can do that job at night when it's cooled down and there's no nosy buggers around to interrupt you.
 
Re: it\'s time to replace the fuel tank...

If you do decide to replace your tank, consider if there might be room for two tanks, each delivering fuel through its own filter. I was very glad I had done this on two occasions in midchannel after taking on dirty fuel [I would only ever fill one tank from any particular supplier].
Engine stops, just turn the taps and swap the supplying tank, sort out blocked filter in port afterwards.
 
Re: it\'s time to replace the fuel tank...

If determined to replace the existing tank, and I side with others here that if it is a grp one I would try to clean it before destroying it, look at Vetus. Although I agree that Tek-tanks make a good product, Vetus are specialists in the field of fuel tanks and they can supply all the fittings that you will need.
 
Re: it\'s time to replace the fuel tank...

Well, that's the GP practice finished now and have had another look at the original post. Sounds like the tank AND the bilge need cleaned out. I did my bilge with very hot water, worked a treat. The boat was in my yard and with the the sea cocks open and the pipes removed all the muck and very dirty water just washed out on the yard floor. Some of the bilge paint lifted but this was easy to patch up later.

My centaur had a 10 gallon (or so) tin tank and was replaced with a 35 gallon bladder. The filler fuel filler was moved out of the cockpit at the same time.

The thing is, do you need to replace the tank because of something else, ie bigger / smaller tank required, filler in the wrong place etc?

Whatever you do it will be dirty and smell which is a good reason to pay someone to do the job for you.
 
Re: it\'s time to replace the fuel tank...

New tanks usually (always?) take the fuel from the top through a 'dip-pipe' that almost reaches the bottom of the tank. This has only one advantage that I can see (that the tank will not empty into the bilges if you get a pipework leak somewhere), but many disadvantages. In my view the apparent increase in diesel bug problems over recent years is due to this issue. If the fuel take of is from the bottom of the tank with a propper sump area it is an easy job to drain off any water sitting at the bottom of the tank through a suitable valve for the purpose. This is impossible to do with the dip-pipe arrangement. The only way to get at any water in the bottom of the tank is to try to pump/siphon it out from the top of the tank and since most have no sump it does not collect in one place so it is impossible to get it all out in any case. If you can't get at the top of the tank, as in my installation, you are stuffed and you just have to accept that there is always going to be some water at the bottom of the tank. The only way to get it all out is to get the tank out and clean it, which is an engine out job for me! Why on earth don't plastic tank manufactureres provide a sump with a valve to drain off the water. They could still use the dip-tube to supply the fuel, but a means of drain off all of the water is essential. Rant over! Bare this in mind if you go for a new plastic tank.
 
Re: it\'s time to replace the fuel tank...

For my part I like dip pipe tanks, two or more if possible.

The disadvantages are minimul if a suction pump, water separator and filter arrangement are available for occasional use.

If it is possible to get to the top of the tank to insert a suction pipe, (filler) just suck everything out, filter it then blast the cleaned fuel back into the tank. Blasting it backwill "stir" up the contents, (water, dirty fuel, bugs etc). Repeat process until the fuel is as clean as you want it to be. Easy ! !
 
Re: it\'s time to replace the fuel tank...

My idea of the ideal set up (much influenced by Calder) is a fuel take up a little way above the bottom of the tank (as you describe) but with an additional drain from the bottom of the tank. Ideally this should exit from a fitting at the top of the tank (holes in the bottom of tanks having obvious drawbacks). I made such a tank from GRP four years ago, using a Tek-Tank inspection cover with out, return and breather fittings, plus a proprietory fitting for the drain line.
Draining sludge/water (or just checking what the liquid at the bottom of the tank looks like) is now a simple matter of opening a tap fitted to the end of the drain hose. It literally takes but a minute. Once primed (yuch!), the bleed hose seems to stay that way. Simple and reassuring.
 
Re: it\'s time to replace the fuel tank...

All this talk of dirty fuel tanks has just landed me with cleaning job on a friends landrover. We sucked the dirty diesel out with an aqua vac. It is a pro one with a big container. Worked a treat. But how did the fuel become contaminated in the first place, a lifetime of filling from the farm tank, that's how. I expect to have the 600 gallon tank to clean out some time soon.
 
Re: it\'s time to replace the fuel tank...

as a subsequent question, given a bucket of say 10 litres of dodgy diesel fuel taken from a dodgy tank, how does one filter it suitable for returning to the boat. My Dad told me they filtered petrol thru chamois leather in the desert duting the WW2 but there may be a more modern approach ??
 
You must log in or register to reply here.

Share this page

Top