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Author: Subject: Fuel tank leak
luke2152

posted on 20/3/17 at 09:32 PM Reply With Quote
Fuel tank leak

Identified a small leak from my fuel tank today. About 1 drip per 2 minutes and leaves a small puddle on the floor overnight.

I've pretty much identified where its coming from although I can't see if its a pinhole or a hairline crack. Seems to be coming from the weld on one of the corners. Photo attached. Reference the green marks I drew the leak appears to start about 2cm below and travels both directions (slightly shaded patch in the photo and just as hard to see in real life. You can ignore the scratch next to the green line as that was me marking before I found my green pen. There is a mark made by handbrake cable further down which I thought was the cause but the leak actually starts about this mark so its not that. But other than these two there's no obvious marks. It must have happened relatively recently because I noticed the smell in the garage.

Access is a little difficult for welding, tank is silkoflexed to the chassis and I shudder to think what kind of precautions need doing before welding a petrol tank anyway. Would epoxy JB weld or similar be fuel resistant enough to deal with a small leak?


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Doctor Derek Doctors

posted on 20/3/17 at 09:48 PM Reply With Quote
That looks almost identical to a leak I had, who made it and when?





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luke2152

posted on 20/3/17 at 10:58 PM Reply With Quote
quote:
Originally posted by Doctor Derek Doctors
That looks almost identical to a leak I had, who made it and when?


From GBS although I don't think they make it themselves. Guess I brought it about 3 years ago.

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CosKev3

posted on 21/3/17 at 06:09 AM Reply With Quote
Who stuck it to the chassis?

Stupid idea that is imo!

Welding is no issue,if you could get the tank out that is!

My m8''s welded loads of alloy tanks, just leave them to dry out for a while before welding and they are fine.
Welding is the only 'proper' fix

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JeffHs

posted on 21/3/17 at 09:11 AM Reply With Quote
Many many years ago I grounded an overloaded A30 on a curb and knocked the tank drain plug causing a leak. I drained, cleaned and applied a large blob of epoxy putty - I can't remember the name of the stuff but it came in 2 tins, 2 different colour putties that you mixed together in equal quantities. It never leaked again.
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40inches

posted on 21/3/17 at 09:33 AM Reply With Quote
I have used Granville Petro Patch Putty to seal a leaking motor bike ally tank with success.The area needs to be clinically clean
and abraded. https://www.amazon.co.uk/Granville-0455-Petro-Patch-Putty/dp/B004OS8N1W
Bonding the tank to the chassis!!!!!!!! Why?

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leon51274

posted on 21/3/17 at 09:36 AM Reply With Quote
Granville Petro patch putty is what I used on my fuel tank and its not leaked for over 2 years.
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David Jenkins

posted on 21/3/17 at 09:44 AM Reply With Quote
POR-15 do a liquid that you pour in the tank and sloosh around. I have no experience of this stuff, so I can't comment on how good it is, but I expect it will be expensive...





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rusty nuts

posted on 21/3/17 at 06:59 PM Reply With Quote
Another vote for Petro Patch , didn't know it was still available. As others have already asked , why Sikoflex? Suspect the best way to cut it would perhaps be a cheese wire type windscreen remover?
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froggy

posted on 21/3/17 at 08:41 PM Reply With Quote
Looking at the etching around the weld it looks like it's been fused rather than adding rod like you usually see on ally work . If it's a crack along the weld with no filler metal rather than a pin hole it's a lot more likely to happen elsewhere if that's how the tanks been welded up . Normally a quality tank has a lovely stack of dimes pattern on any weld Seams





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BenB

posted on 21/3/17 at 09:56 PM Reply With Quote
POR15 do a not very expensive tank sealant but you use gravity to get the stuff to the right place which might be tricky... Technoweld would work but would need a big torch with that surface area....
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luke2152

posted on 21/3/17 at 11:14 PM Reply With Quote
Yeah i initially silkaflexed it to chassis to make sure it wouldn't vibrate but then it stuck so well i didn't need to bolt it down. Maybe not so clever in retrospect. Still i don't think it will be too hard to remove. Was thinking cheese wire method too like rusty nuts suggested. Someone PM'd me a story about that whole weld failing suddenly which sounds rather scary. I'm allergic to fire
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snapper

posted on 22/3/17 at 07:45 AM Reply With Quote
Petrol patch will do it but it's not permenant especial if exposed to road grit and water
I used POR 15 and whilst you need to clean and prepare the tank with chemicals that comes with the full kit carefully and dry the tank out completely once you have used the POR 15 it produces a tough fuel proof layer in the tank.
I even used it to line an intake manifold that had bad welding and porous tubes





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CosKev3

posted on 22/3/17 at 07:59 AM Reply With Quote
If you are going to remove the tank get it welded end of!

All these sealers etc are only really acceptable if the tank can not be removed imo

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luke2152

posted on 22/3/17 at 04:46 PM Reply With Quote
quote:
Originally posted by CosKev3
If you are going to remove the tank get it welded end of!

All these sealers etc are only really acceptable if the tank can not be removed imo


Ah yeah thats what I mean - if I remove the tank I'll get it properly welded.

I think I'll patch it up for now and keep a close eye on things to see if it spreads. Pull it out and get it welded if need be.

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BenB

posted on 22/3/17 at 06:38 PM Reply With Quote
You could just some of this stuff

http://www.frost.co.uk/oyltite-stik-seals-oil-leaks-thread-sealer.html

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BenB

posted on 22/3/17 at 06:40 PM Reply With Quote
The instructions just say you have to vigorously rub your stick into the crack after peeling back the outer coating.

Reminds me of sex ed lessons...

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