Skirrow
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| posted on 5/5/13 at 12:31 PM |
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"Welding" a tank full of fuel
Just discovered a fuel leak. There's a stainless pipe on the top of the tank which connects to the flexible fuel filler pipe. The pipe should
have been welded on at the build stage by the looks of it but it looks to have just been stuck on with some sort of sealant. Anyway, the sealant has
now failed which means fuel leaks into the boot.
I know I can't weld it with traditional means without a fair amount of messing about to rid the tank of vapour and fuel, but can anyone
recommend anything I can reseal and attach it back with? Was thinking of that liquid metal or similar?
[Edited on 5/5/13 by Skirrow]
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coyoteboy
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| posted on 5/5/13 at 12:34 PM |
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You want to risk a bonded fuel tank? Not me, and I wouldn't be recommending it to anyone either! Do it once, do it properly, don't die in
a ball of fire. First sign of an impact and a bonded area like that (it's not even bonded well for christs sake, the adhesive is several mm
thick!) will pop right off and cover you, your passengers, likely your exhaust and anyone else in the vicinity with fuel.
And who the hell built that in the first place? It's not even bolted and bonded, just bonded - madness.
[Edited on 5/5/13 by coyoteboy]
[Edited on 5/5/13 by coyoteboy]
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Skirrow
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| posted on 5/5/13 at 12:39 PM |
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Wasn't me who built it, I know that much!
I was hoping there would be some safe way of bonding it. Wasn't planning on using the safe stuff that was used there...
It's worrying really, I had no idea it was like that until I discovered the leak.
I actually thought the leak was from where the flexible fuel pipe joined the metal. Gave it a twist with my hand and the whole thing popped off!
[Edited on 5/5/13 by Skirrow]
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britishtrident
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| posted on 5/5/13 at 12:49 PM |
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You know the answer before welding remove the tank then wash it out followed by steaming out (use a steam wall paper stripper) to get rid of any
remaining petrol in the seams.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Skirrow
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| posted on 5/5/13 at 12:49 PM |
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So, assuming bonding it is out, how do I weld the tank without blowing it up? Would filling it with water to remove any fuel vapour be safe?
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Skirrow
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| posted on 5/5/13 at 12:51 PM |
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quote:
Originally posted by britishtrident
You know the answer before welding remove the tank then wash it out followed by steaming out (use a steam wall paper stripper) to get rid of any
remaining petrol in the seams.
Cheers, I guess I have to face reality then. First day out this summer was yesterday and was hoping to get to Stoneleigh tomorrow but I'm not
sure they'd let me in if I was being chased by a fireball.
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ali f27
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| posted on 5/5/13 at 01:01 PM |
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Hi how about some red hylomar and rivet it would get you to stoneleigh and may work for ever but if not can take off and weld later
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Macbeast
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| posted on 5/5/13 at 01:04 PM |
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Make a neoprene or cork gasket and use screws to fix it to the tank body ? Works for fuel level senders.
I'm addicted to brake fluid, but I can stop anytime.
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Thailoz
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| posted on 5/5/13 at 01:11 PM |
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what he said
It may sound a dumb Question to you but to others it may be an eureka moment
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craig1410
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| posted on 5/5/13 at 01:25 PM |
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Get some of the stuff they use to glue the Lotus Elise chassis together. I think it is an epoxy adhesive. Not sure if it is fuel resistant though so
would need to check that. It should be strong enough.
To be honest, in a crash with the fuel tank on the Locost so exposed to rear impact, I would doubt it would make much difference if it is a welded
tank or if it has a (properly) glued panel in it. It's going to be compromised. Look at all the bolts and things in the rear area around the
tank - it's going to be punctured.
Best stuff I've come across for fixing fuel leaks is Plastic Padding Leak Fix. You can get it in Halfords. Here is the Loctite spec page for it:
http://www.loctite.co.uk/fullproductlist-plastic-padding-4997.htm?countryCode=uke&BU=industrial&parentredDotUID=productfinder&redDotUID=10
00000JB9360360652
and here is the Halfords page:
http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_223933_langId_-1_categoryId_255230
Described as petrol resistant on the Loctite page although Halfords don't advocate using it to fix petrol tanks, probably for legal reasons.
Might be okay for a temporary fix, ideally backed by some mechanical fixing as well (eg. rivets or rivnuts or something). I used this a while back to
do a temp repair on a fuel tank seam leak although ultimately I got a new tank made up under warranty by the company who made the defective one. It
certainly stopped the leak long enough for me to finish prepping the car for SVA and get the new tank into which I could transfer the 15 litres of
fuel I had put in it. I just tipped the car up on its side to allow me to dry and clean the leaky bit before rubbing down with some emery to provide a
key for the leak fix. I've also used leak fix before on an old Rover 820 Vitesse which had a badly corroded tank. Again it saved the day and
allowed to me to fix the problem for long enough to source a new tank and use up the 68 litres of fuel I had just put in it! I had to syphon the fuel
into big plastic buckets initially which was more than a little bit worrying but I had to get the fuel level low enough to carry out the fix and let
it set before putting the fuel back in. Worked a treat though.
Usual disclaimers apply - I take no responsibility for anything, ever! 
Good luck,
Craig.
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mad4x4
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| posted on 5/5/13 at 01:52 PM |
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Make up a gasket as a tempaory fix and then fix properly once back from stoneligh.
Scot's do it better in Kilts.
MK INDY's Don't Self Centre Regardless of MK Setting !
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Skirrow
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| posted on 5/5/13 at 03:21 PM |
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Cheers for the help fellas. Due to running out of the garage time my wife has allocated to me I've ruled out stoneleigh and might as well go for
a proper fix rather than anything temporary.
Like the idea of a cork gasket and screwing the plate on as it saves draining but is that as safe as it being properly welded?
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Skirrow
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| posted on 5/5/13 at 03:22 PM |
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Also, I only have an electric drill. Fuel vapour and those little sparks inside the drill could result in a large bang...
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JAMSTER
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| posted on 5/5/13 at 04:57 PM |
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i did this works well
quote:
Originally posted by britishtrident
You know the answer before welding remove the tank then wash it out followed by steaming out (use a steam wall paper stripper) to get rid of any
remaining petrol in the seams.
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Ben_Copeland
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| posted on 5/5/13 at 04:58 PM |
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Put the drill inside a bag, stops the sparks??
Ben
Locost Map on Google Maps
Z20LET Astra Turbo, into a Haynes
Roadster
Enter Your Details Here
http://www.facebook.com/EquinoxProducts for all your bodywork needs!
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Wadders
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| posted on 5/5/13 at 05:49 PM |
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Windscreen bonder will stick it no problem, but you need to key the parts and use the proper primer on both surfaces.
Al.
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spiderman
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| posted on 5/5/13 at 06:51 PM |
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quote:
Originally posted by Skirrow
So, assuming bonding it is out, how do I weld the tank without blowing it up? Would filling it with water to remove any fuel vapour be safe?
I have used this method before on many occasions and I am still here. You can also do the same with Argon gas or some other inert substance. What
you need to do is remove all oxygen from the tank as all explosions/fire require fuel/oxygen/and an ignition source, remove any one of the three and
you are safe.
Spider
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motorcycle_mayhem
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| posted on 5/5/13 at 08:54 PM |
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Please don't use epoxy resin, please don't. It's not just the aryl hydrocarbons that it isn't stable to, the ethers alcohols
and other polar components in petrol are effective removal agents.
As a complete unsafe bodge, as has been mentioned, any quality PU (polyurethane) adhesive/sealer will survive temporarily. This is used as a
constructional adhesive, including chassis bonding. No, it isn't fuel proof, or fool proof, but it will survive long enough to enjoy the car for
a while. You won't find Sikaflex mandating it's use on solvent tanks! (and neither should they).
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bi22le
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| posted on 5/5/13 at 10:28 PM |
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I had a small split in my fuel tank and used a metal repair glue to fix it. It stated it was safe for use with oil and petrol. Also very heat
tolerant. It seemed quit brittle when dry but has worked.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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Bare
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| posted on 6/5/13 at 02:58 AM |
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Ridding an empty Fuel tank of Fuel vapors for welding on it is NO Joke.
Lotsa methods: most range from suicidal to it might work /russian roulette.
One old welder recounted his method. (plausible given his age though :-)
Remove tank.. fit petcock valve onto it's exit.
Fill with water to overflowing.
Hold a wee flame above the overflowing with water filler neck.
Open the drain valve..
Hold the burning flame in position until ALL the water has drained out.
He claims is safely weldable at that point as all vapors have either been expelled or burned.
Dunno.. never tried it.. But? he was still alive and seemingly unburnt.
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britishtrident
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| posted on 6/5/13 at 06:28 AM |
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This is nothing to do with the tank up blowing up but I would give the plate some nicely rounded corners (at least R 10mm) before welding
it on --- right-angled corners are asking for the tank to crack at the welds.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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doobrychat
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| posted on 6/5/13 at 07:59 AM |
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i have yet to find anything other than welding to be successful to seal petrol..
advise is to take tank out, wash with water then what i do is fill tank with exhaust fumes as non combustable by running it under a car exhaust for
10-15mins..
i do this to motorcycle petrol tanks regular due them splitting when they hit the deck or having a large dent..
good luck..
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jelly head
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| posted on 6/5/13 at 08:22 AM |
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I was told years ago that the way to weld a fuel tank is to fill it with water as much as possible so that most of the air/ fuel vapour is forced out
so that if any remaining vapour does ignite you'll just get a pop and not destroy your garage.
Cant say that i've tried it but as a method makes sense to me.
I think someone should at test the theory!!
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wicket
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| posted on 6/5/13 at 08:39 AM |
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Surely the correct thing to do is dump this suspect tank and fit and properly built one. It will cost you money for sure but your life and maybe
others is PRICELESS
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Skirrow
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| posted on 6/5/13 at 10:38 AM |
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Thanks for all the advice. I think the tank itself is OK. It appears to be an off the shelf welded tank but presumably the filler pipe wasn't
fitted and the builder didn't have the gear to weld it so decided to bond it.
I've spent a bit of time reading online opinions regarding welding the used tank and I'm not that keen on having a go at welding it myself
even full of water. Chances are it would be fine but there's a small chance I might not get all the vapour out and I really don't want a
thermal incident of any description.
My current plan is to drill the tank with a hand drill to avoid sparks and screw the plate on with a cork gasket. Then use some of that aviation fuel
tank repair stuff on top of the screws to seal them and prevent fuel getting through the screw holes/threads.
I can't think of any safety issues with that, if anyone else can it would be appreciated to hear them.
Failing that, I'll just get a new tank
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