Leaking Fuel Tank

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Morph
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Leaking Fuel Tank

Postby Morph » Mon Jun 08, 2009 3:01 pm

Well, with all this wet weather Gadget and I decided to ground EPH for a weeks and fix the leak in the one wing tank.

There were two choices 1. fix it in the wing, or 2. cut the tank out of the wing, repair and reinstall, with includes recovering etc

So the obvious choice was try the easy route and fix it in the wing. This requires a magical tin of dragon snot that is fuel/solvent proof, stays flexible, thick enough to plak on your woolen jersey sleeve, strong enough to never come off your woolen jersey sleeve, fast drying and readily available. Enter Scotchclad EC776 (^^) (^^)

Sourcing this stuff is NOT easy. But I phoned 3M, (they have a farm full of dragon's with bad colds it appears :wink: ) and I managed to get the number of the local rep for my area. I then phoned him and told him what I want, in 1 liter, and he gave me the name of one of his dealers. Following my call to them and their call to the local rep the stuff was ordered and a week later and R275 poorer I got the snot.

I suspected that the tank was leaking from the front seam. We took the wing off and stood it on it's leading edge. There was a little bit of fuel in it and after a few moment we could see it starting to drip out.

I used a cup full of MEK (or Acetone) to clean the tank out and let this dry thoroughly. Next I put a cup full of EC776 into the tank and swirled it around, trying to cover all the corners. It was then left for 2 days standing upright on the leading edge. At the same time I left some in a off cut 2liter plastic bottle to use as a sample and to test for dryness. 2 days later, I gave her a second dose, and let it dry until the weekend. At the same time I mixed up some Epidermix 372 epoxy to closed what I thought was the obvious crack on the outside of the tank, just in case.

Sat morning we put 10 liters in the tank, leaving it standing upright, marked the level with a pencil on the side of the tank and went for coffee. 1 hour later the fuel hadn't dropped a mm. 8)

So finally the wing is back on, and EPH is back in the air (^^) (^^) (^^)

BTW, 1 liter covers 6sqm or a 1000liter cube.
Designed for aviation purposes, compatible with mogas and avgas but not Jet Fuel.

Good stuff this Dragon Snot
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EC776.pdf
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Re: Leaking Fuel Tank

Postby weedy » Mon Jun 08, 2009 3:30 pm

Does mogas not sometimes contain alcohol?
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Re: Leaking Fuel Tank

Postby Morph » Mon Jun 08, 2009 4:00 pm

According to Engen
Do all petrol brands contain alcohol?
All the brands of leaded 93-octane petrol in the biggest part of the Gauteng area and parts of the North West and Mpumalanga provinces contain alcohol.
Is alcohol present in unleaded petrol?
No. Alcohol is not added into unleaded petrol.
(http://www.engen.co.za/home/server/faq/ ... efault.asp)

You shouldn't be using leaded fuel anyway, except maybe on VW powered aeries.
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Re: Leaking Fuel Tank

Postby bluesmancoops » Tue Jun 09, 2009 11:13 am

vw aeries also use unleaded we just add valve ease
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Re: Leaking Fuel Tank

Postby georgeh » Wed Jun 10, 2009 10:39 am

Hi guys
This is the first time i,m trying this, i,m useless with computers. Never tried a forum before.
I own a Shadow and have had endless problems with a fuel float switch leaking at the flange and the centre pin. will this "Dragon snot" work in this area?
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Re: Leaking Fuel Tank

Postby Morph » Wed Jun 10, 2009 11:11 am

can you take some photo's of this area? Is it part of the Fuel Level sensor? I need more information.
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Re: Leaking Fuel Tank

Postby georgeh » Wed Jun 10, 2009 1:52 pm

Sorry, battled to attach a picture. I'm not a computer geek. Its a regular car type float sendor. The problem is that the craft has a top tank that feeds a bottom tank and the sendor is on the side of the bottom tank. the fuel eventually stars to seep through all the areas where there bolts with thread.
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Re: Leaking Fuel Tank

Postby Morph » Wed Jun 10, 2009 2:12 pm

Got it,

I reckon this stuff will probably work. Take the lower tank out, degrease with MEK or Acetone, especially around the sender unit. Pour some of this stuff in and lay the tank with the sender flange at the bottom, i.e. the stuff will dry and seal around the threads. Maybe do a few doses to get it nice and thick. It forms a flexible rubbery layer. I know some guys slightly (very slightly) pressurise the tank and force the sealer into cracks and threads. Keep it away from the working components of the resitive float mechanism.

Where abouts are you based
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two tanks.jpg
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Re: Leaking Fuel Tank

Postby georgeh » Wed Jun 10, 2009 3:14 pm

Ok! S you a boffin with the computer. Almost perfect. The sendor mount is on the side, not on top. I was looking for something fuel resistant that i could use like a gasket maker. No one seems to have a product that is fuel resistant. I could make a new back plate with a gasget between, but without a fuel resistant sealant i'll always have the same problem. I live in Pinetown and fly out of Light Flight, Coto Ridge which is just outside Pietermaritzburg. Where are you? By the way, you don't know of a Streak Shadow out there suitable for restoration?
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Re: Leaking Fuel Tank

Postby Morph » Wed Jun 10, 2009 3:29 pm

They normally use gaskets made out of cork for fuel level senders. Once you have made a gasket and redone it, there is no harm making doubly sure and using this stuff as well

Nope no idea on a Shadow
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Re: Leaking Fuel Tank

Postby georgeh » Wed Jun 10, 2009 3:58 pm

Ok, thanks. I'll get onto the 3M guys now and hope they have the stuff here. Will let u know if it works.
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Re: Leaking Fuel Tank

Postby Morph » Wed Jun 10, 2009 4:19 pm

Make a dummy tank out of the bottom half of a plastic bottle and put a dummy flange in it. Try ensure it's leaking a little. Then pour some of the stuff in, let dry for 24 hours and test. Might need a few layers

Once you are happy, then strip the tank off and go mal
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Re: Leaking Fuel Tank

Postby AlanM » Thu Jun 11, 2009 8:37 am

Phone Rob 083 648 1132
He had a similar problem on an Aquilla tank and fixed it successfully using Thread coils, they tap into an existing hole where the thread is stripped so you can then bolt down the gasket firmly.

Hope this helps
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Re: Leaking Fuel Tank

Postby MAGNIficent » Wed Aug 05, 2009 12:53 pm

Morph

Do you have any details of the rep or where you bought the Sctochclad EC776?

Thanks
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Morph
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Re: Leaking Fuel Tank

Postby Morph » Wed Aug 05, 2009 1:27 pm

I spoke to 3M headoffice and asked for their local rep.

Telephone: +27 11 806-2000

Durban:

Tel: +27 31 265-1200
Fax: +27 31 265-1270

http://solutions.3m.co.za/wps/portal/3M ... p/Contact/
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