Fuel Tank Issues - SIlicon removal

Hi Guys,

Last week I found that my fuel tank had a leak in it, putting 60l into the bilge and 60l left in the tank.  Got the rest of the fuel out of the tank this morning (it is an inhull tank) but have found that it has been foam filled down the sides for insulation (I will be able to get this off with some hard work) 

The problem is that I have found the tank to be siliconed to the base and there isn't really much of a gap to get in there and leverage it out.  Just wondering if anyone knows of any chemicals which will break down the silicone without compromising the fibreglass?

Cheers,

Adam

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sea-kem's picture

Posts: 14983

Date Joined: 30/11/09

I know this might seem a bit

Sun, 2011-10-23 12:10

I know this might seem a bit out there and just trying to think laterally. Maybe dry ice in the tank to freeze the silicone .Or maybe boiling water to soften the Silicone. Just some ideas to throw in the hat.

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Posts: 912

Date Joined: 23/07/10

If there is enough gap to fit

Sun, 2011-10-23 13:16

If there is enough gap to fit thin wire, then you should be able to saw it loose slowly if there is minimal room, faster if there is more room.

Posts: 9358

Date Joined: 21/02/08

Good idea, just use some

Sun, 2011-10-23 13:30

Good idea, just use some trace wire, we used to do this at work for cutting it of metal.

Silicon is pretty much inert. Its not going to soften in any solvent you have handy, and boiling water isn't going to affect it either.

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Adam Gallash's picture

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Date Joined: 29/11/05

unfortunately

Sun, 2011-10-23 13:44

Unfortunately there is no room - it is about 2m long and completely tight in there.  All I can hope is that it is just the front and back siliconed, not the whole thing.  Will give it a shot though, any other ideas welcomed.

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grantarctic1's picture

Posts: 2546

Date Joined: 03/03/11

As above

Sun, 2011-10-23 13:45

As above Adam, the best way i have found is to cut the silicon with a blade or thin wire. There are some products now that can reliese the silicon and are aplied with a corking gun to the join.

We use thinners as well but i don't think the fibreglass would like this , in sensitive areas we use turps or Metho, but i usualy do a sample first to make sure it dose not stuff up the surface.

Cheers Grant

fishy fingers's picture

Posts: 1719

Date Joined: 28/04/07

try braid

Sun, 2011-10-23 18:10

some strong braid with a handle on both ends use it like a saw u may need 2 people to get the action though (thats if you have the room to get something under the edge) maybe tap in a small timber wedge or better the plastic wedges for tiling small but should be able to tak a bit of hamering to get a start with the braid

carnarvonite's picture

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Date Joined: 24/07/07

Jeffro

Sun, 2011-10-23 16:22

Nip round and see Jeff, get some of that black line he's got on the big snapper winch to feed in under the tank like the others have said. Its very strong and still rough enough to saw through the snot.

Adam Gallash's picture

Posts: 15644

Date Joined: 29/11/05

Good call

Sun, 2011-10-23 18:47

Good call re the braid I will give that a shot.  I've been trying with a hacksaw, blades, knives etc and got about 1/8th done, but the braid may save me a bit of work, will see how that goes.  Cheers.

On another note, from what I have done so far I can't possibly see where the hole or crack in the tank has come from.  Theres no one in town that can do an air pressure test, is there any other way I can test the tank's integrity without refuelling it (with fuel or water)  (I have thought water but then need to find a way to discard it - without just pouring it into the drain pipe)

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marble's picture

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Date Joined: 03/09/09

Should be easy enough to

Sun, 2011-10-23 20:13

Should be easy enough to pressure test it once you get it out, just have to put a bit of hose on the outlet and fold it over and hose clamp or wire up then the same with the inlet hole. Jam an air nozzle into the breather and keep pumping air in while a mate goes aroung the whole thing with water and detergant to find the leak. You dont need heaps of pressure in there for it to work.

Its a bit dodgy but if you do fill it with water to find the leak you can pour the water out and burn off any residual fuel mixed with the water, told you it was a bit dodgy . . .

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sea-kem's picture

Posts: 14983

Date Joined: 30/11/09

Either needs to be degassed

Sun, 2011-10-23 20:36

Either needs to be degassed before welding or filled with water. You can buy a three can dye penetrant testing kit usually from Repco or somewhere like that. It will give an accurate pinpoint on where the crack is. Being a big tank it will be worth the money. Don't know who's in your industrial area up there Adam but someone might have the kit. The dye pen is used on all the non ferrous metals. The welds need to be cleaned very carefully beforehand. It will give you peace of mind knowing you have found all the faults properly.

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just dhu it's picture

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Date Joined: 14/05/09

silicon removal

Sun, 2011-10-23 21:41

Adam , i noticed at the shop last week theres a silicon removal stuff in a tube that you put on silicon beads and it turns the silicon to  jelly for easy removal  if you can get to all the areas, otherwise i would use the olf Fireline braid idea as it pretty rough edges to cut