Aluminium fuel tank

crui05 · 31 March 2021, 18:24

hi all,
i have a viking 5.5. the service guy suggests my fuel tank is full of "rubbish" so wants to convert to outside plastic tank.
i would rather keep the the original tank as it means trips further afield. do i really have to abandon my original tank. cant it be cleaned out. ?

Jon Tallis · 31 March 2021, 18:41

Quote:

Originally Posted by crui05

hi all,
i have a viking 5.5. the service guy suggests my fuel tank is full of "rubbish" so wants to convert to outside plastic tank.
i would rather keep the the original tank as it means trips further afield. do i really have to abandon my original tank. cant it be cleaned out. ?

Probably depends on whether the tank is baffled, has an access hatch or just hose takeoffs.
If it has an access hatch (and you can get to it) and isn't baffled, or has hatches in each compartment then yes it can definitely be cleaned out.
If not then, not without modifying the tank

crui05 · 31 March 2021, 19:00

it has a inspection hatch above it but thats more to get at behind the consol. i cant see a way of getting into the tank other than the filler hatch.
i wondered it it could be exchanged for a replacement tank

CUSAC · 31 March 2021, 20:11

I’ve got a tornado with tanks under the deck so similar setup (Viking range by same manufacturer I believe). There was all sorts in the fuel as it had sat for years. No access hatch but pumped as much as possible out through the filler hole and treated with an enzyme treatment. Kept flushing with new fuel and filtering.

Had a couple of blockages during the first season but I knew that was likely so had portable tanks on deck ready. After a few months of new fuel and a couple of filter changes (when I noticed sediment in the filter bowl) it all seems fine now.

Orwell boy · 31 March 2021, 20:48

Is access possible via the level sender unit mounting hole ?

crui05 · 01 April 2021, 09:16

thanks everyone for your input.
i cant find a sender unit Hole. must be one im sure as i have a fuel gauge (still working) but the only hatch i can see is the one for getting at the back of the consol.
how could i pump out "rubbish" thorough the filler neck ?

CUSAC · 01 April 2021, 09:18

Quote:

Originally Posted by crui05

thanks everyone for your input.
i cant find a sender unit Hole. must be one im sure as i have a fuel gauge (still working) but the only hatch i can see is the one for getting at the back of the consol.
how could i pump out "rubbish" thorough the filler neck ?

Same with mine. The fuel sender was back under the deck inaccessible with no access hatch (why would they build it like that?!).

We made up a crude contraption using an old manual bilge pump, a length of hosepipe and a lot of tape. Did the job well enough.

crui05 · 01 April 2021, 09:30

wondered if i could get the crap out of the tank at just before the filter end (near the engine.)
would so love to have fuel in the tank as it holds so much more and safer than dealing with plastic tanks with swapping over. also limiting distance with two 25 l tanks at rear.
i also wondered if the boat sat better in the water without fuel tanks in the stern ?

CUSAC · 01 April 2021, 09:51

We tried that but the small bore of the fuel hose meant it wasn't getting much out, plus the pick up tube doesn't appear to go right to the back of the tank. The hose allowed us to get right to the back of the tank.

Depending on the size of your tank I agree the weight distribution change could be significant. Our tanks are 2x100L so was never going to be an option to run portable tanks long term.

willk · 01 April 2021, 11:08

Quote:

Originally Posted by crui05

the service guy suggests my fuel tank is full of "rubbish" so wants to convert to outside plastic tank.

Yeah, cos he looked inside your tank. The one with no access hatch. Easy shout for him, bigger probs for you!

That said, he might be right - but chances are it's a bit of crud gathered down around your pickup pipe that is getting sucked back into whatever filters you have. If it was me, and I had only the info and setup you have, I'd go out and invest in a top quality filter and fit it where you can access it quickly. Something with cartridges like a RACOR - you can carry spares and select different levels of filtration. Carry a spare filter for whatever filtration is on the engine as well. Run that out for a trip and check the filter - see what you've caught.

Service guy is overlooking the potential for a dirty fuel purchase going forwards - even plastic tanks suffer that from time to time!

Pikey Dave · 01 April 2021, 12:30

Quote:

Originally Posted by willk

Yeah, cos he looked inside your tank. The one with no access hatch. Easy shout for him, bigger probs for you!

That said, he might be right - but chances are it's a bit of crud gathered down around your pickup pipe that is getting sucked back into whatever filters you have. If it was me, and I had only the info and setup you have, I'd go out and invest in a top quality filter and fit it where you can access it quickly. Something with cartridges like a RACOR - you can carry spares and select different levels of filtration. Carry a spare filter for whatever filtration is on the engine as well. Run that out for a trip and check the filter - see what you've caught.

Service guy is overlooking the potential for a dirty fuel purchase going forwards - even plastic tanks suffer that from time to time!

Wot he said^^^^^^
You could also rig up a makeshift flushing system with a pump & filter. Stick a few gallons of fuel in the tank, make a re-circulating system where the pump draws fuel from the tank via a filter & dumps fuel back to the tank. Leave it running for a few hours. Start with a coarse filter & work up to a fine 2 micron.

crui05 · 01 April 2021, 15:15

thanks guys for your input. as usual you come up with a solution. will investigate it.
maybe then my boat will handle better with correct weight distribution.

davej · 03 April 2021, 18:32

Quote:

Originally Posted by crui05

thanks guys for your input. as usual you come up with a solution. will investigate it.
maybe then my boat will handle better with correct weight distribution.

We had a similar problem on our club tornado years ago, always blocked fine jets in the yam 115, it was a pain in the butt cleaning the jets after every trip out. The sh1t got through the two filters. However, we siphoned off all we could filled up with water and hole sawed a 130 mm hole on the top of the tank that was under the drivers seat.

We then poured buckets of hot soapy into the tank through the fillet and siphoned it all off endless times. We then dried it off and one of our members made an Ali plate which was held in place with captive nuts. All good ever since!

Matt · 07 April 2021, 09:42

Yup, I think this is what I'd do in the same circumstance.

Quote:

Originally Posted by davej

We had a similar problem on our club tornado years ago, always blocked fine jets in the yam 115, it was a pain in the butt cleaning the jets after every trip out. The sh1t got through the two filters. However, we siphoned off all we could filled up with water and hole sawed a 130 mm hole on the top of the tank that was under the drivers seat.

We then poured buckets of hot soapy into the tank through the fillet and siphoned it all off endless times. We then dried it off and one of our members made an Ali plate which was held in place with captive nuts. All good ever since!

pritch · 13 April 2021, 14:51

Quote:

Originally Posted by Matt

Yup, I think this is what I'd do in the same circumstance.

I've got the same problem with my old Tornado 5.8 and Yamaha F100 at the mo.....

is the fuel tank baffled?? Just wondering how much space i'll have to clean it? Also, hoping to stick a camera in there to inspect.....

Matt · 13 April 2021, 15:12

Some of the ebay USB endoscope cameras give you 1080p, have a built in light for illuminating dark places and are cheap. I have one - it's decent enough.

It is of course entirely possible for a tank to be too knackered to clean out well enough to re-use. But in line with the above - you don't know until you know, it's all worth a go.

Also, while acknowledging it's a lot of work to cut out the floor to replace a built in tank - if you do it carefully so you're not cutting the whole floor out, only what is required, then it's doable.

One of my old boats the tank was too rusty and I removed the whole thing. It wasn't too bad.
Current boat would be a bit of a nightmare - there's quite a bit of stuff on top of the floor now that'd need removing too - rear seat bench, front seat boxes and so forth. I think disassembly would be quick, but putting it back together would be a pain.

Matt · 13 April 2021, 15:32

Also, a note on anyone getting a new tank fabricated:

1. Do it in aluminium and then get it powdercoated externally.
2. Have baffles made as a kind of concertina shape that folds in, and only have them welded on either the top, or the bottom?

Why?
a. Stainless hardens and cracks
b. Tanks "pant", especially when you've got 200+ litres in there and you're going over the rough stuff bouncing around.

That little tack weld to hold the baffle top and bottom won't hold and will rip out.

You might be fine with a stainless tank and baffles welded top and bottom 90% of the time, but sods law you'll be a 10%er.

Of course, you can make the tank out of girders so it doesn't move at all - that'd also be OK.