Would you weld a petrol tank?

Would you weld a petrol tank?

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52classic

Original Poster:

2,447 posts

209 months

Tuesday 27th September 2016
quotequote all
Crazy idea I know, but with the support of the PH crew......

Zodiac MKII fuel starvation problem. I think we've isolated the cause as st in the tank. Previously pressure washed and slosh sealed through the existing holes so next plan is to open it up and clean again before fitting some sort of mesh filter to the pick up pipe.

My thoughts are that if the tank is (emptied of petrol!) filled to the brim with water, then it should be OK to disc cut a square hole say, 150mm. (I imagine that the water would cool the disc but that it would still work.) To close it up again I'm thinking something like a patch cut from a copper cylinder, including the immersion heater boss which would be soft soldered to the top side of the tank so as to give an access hatch in case of further problems.

So firstly, do you think it is safe to carry out? Is copper and solder OK with petrol? What's the chances of the 'fix' being effective.

SystemParanoia

14,343 posts

197 months

Tuesday 27th September 2016
quotequote all
no harm in giving it a go.

the only other option is to by another tank... but if it does'nt work you'll have to do it anyway, so nothing to lose in my opinion

williamp

19,217 posts

272 months

Tuesday 27th September 2016
quotequote all
they showed a guy doing this on wheeler dealers. He filled it with water and then welded it with no problems. Dont simply empty it and then start: lots of baffles where old fumes can hide, etc

edit: its the TR6 epiode if you can find it.

Edited by williamp on Wednesday 28th September 17:42

52classic

Original Poster:

2,447 posts

209 months

Tuesday 27th September 2016
quotequote all
Wow! Fast response as ever!

Thanks for your support, I now have a lot more confidence to give it a go.

andygtt

8,344 posts

263 months

Tuesday 27th September 2016
quotequote all
Had more than one alloy tank welded to modify it, always filled with water first left overnight then emptied.

Peanut Gallery

2,418 posts

109 months

Tuesday 27th September 2016
quotequote all
I have helped mod an old mini tank, he had emptied it, rinsed it many times, left it soaking, etc, worked fine! - due to the amount of moding that was needed we used gas welding on an empty tank, and I am here to say that we did not blow up!

I repeat, the tank had been emptied and rinsed many times before we lit the oxy-acetylene torch.

anonymous-user

53 months

Tuesday 27th September 2016
quotequote all
You need to get the tank nice and hot to drive off any petrol vapour that will sit in the seams and pores of the metal (especially on an old tank). Best option is to get insides and outsides heavily stream cleaned!

Failing that, empty tank, and slosh in a couple of kettles worth of boiling water and some de-greaser. Slosh around for a bit, then drain and leave tank to vent for a few days. If you don't want to fill it with water for the cut, just use a hairdryer or hot air gun (on "cold" setting) to blow a nice stream of fresh air into the tank while you cut it, which will prevent a rich enough mixture forming that can ignite.

52classic

Original Poster:

2,447 posts

209 months

Tuesday 27th September 2016
quotequote all
Some good ideas there. Thank you all. God willing I'll let you know what happens.

cmsapms

707 posts

243 months

Tuesday 27th September 2016
quotequote all
If you've got a steam wallpaper stripper, feed the pipe from this into the tank and pump steam through it for 10 mins or so. This worked for me.

julian64

14,317 posts

253 months

Tuesday 27th September 2016
quotequote all
I've done this a couple of times. always filled with water and them emptied.

Are people suggesting they would try to weld with the tank full of water. How would that work then smile

Spangles

1,441 posts

184 months

Tuesday 27th September 2016
quotequote all
I've heard it done with exhaust fumes being blown through the tank. And it wasn't from the next of kin.

stevieturbo

17,229 posts

246 months

Tuesday 27th September 2016
quotequote all
Ive done it before. As others have said, it's not so much the petrol that is the risk, but any petrol vapours that may reside within the tank.

Filling with water, cleaning, etc etc can all reduce the risks to pretty much zero.

I welded a tank must be 20 years ago after I drove over a boulder and it punctured. I did empty and clean the tank first...then hid behind a sheet of plywood whilst aiming a blowtorch into it once cleaned to see if anything went bang lol.

Nothing did and I welded it up after that.

But both on WD and GMG....seemingly there are places that can fix such tanks, by lining them with some product ?

Frost also sell a POR15 product for repairing such a tank too ?

Peanut Gallery

2,418 posts

109 months

Tuesday 27th September 2016
quotequote all
julian64 said:
Are people suggesting they would try to weld with the tank full of water. How would that work then smile
If the repair is on a corner, you 95% fill the tank, position it so that the corner you are working on is at the very top, and all your welding points are above the water level - with a small extra gap down to the water level to allow the metal to heat up enough.

Bonus part of this is there is reduced areas of heat damage to the paint, and you can check for leaks very easily!

But then again the tank is rather heavy!

Allan L

779 posts

104 months

Tuesday 27th September 2016
quotequote all
Tanks on older cars were soldered so in that case it is possible to dismantle the tank, clean it out and then re-assemble it - I had that done to one of mine.
I expect the Ford in question is too modern for that, but the point of telling you that is that you could solder the repair patch rather than weld it.

stevieturbo

17,229 posts

246 months

Tuesday 27th September 2016
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anonymous-user

53 months

Wednesday 28th September 2016
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I worked with a chap years ago whose brother was killed at RAF Benson during the war trying to hot repair a Lancaster fuel tank. He always did fuel tanks as a result because lightning never strikes twice and all that.

chammyman

123 posts

111 months

Wednesday 28th September 2016
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The biggest issue I have had welding tanks is that they are usually so thin you just blow holes as they are rotten everywhere inside.

anonymous-user

53 months

Wednesday 28th September 2016
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There used to be a plastic material that set hard. Don't know what its called but I've seen it a few times. I've used chewing gum when I split a tank on a kerb and can confirm petrol is a quick solvent of gun it ended up everywhere.

Allan L

779 posts

104 months

Wednesday 28th September 2016
quotequote all
V6Pushfit said:
I worked with a chap years ago whose brother was killed at RAF Benson during the war trying to hot repair a Lancaster fuel tank. He always did fuel tanks as a result because lightning never strikes twice and all that.
(a) lightning can strike twice (I know a man who had lightning strikes in an aeroplane on two separate occasions!)
(b) using statistics as a safety logic puts one in mind of the air passenger who always travelled with a bomb in his baggage, after he had read that the odds against there being two bombs on an aircraft were some 10 million to 1 higher than for a single bomb!

itiejim

1,821 posts

204 months

Wednesday 28th September 2016
quotequote all
The advice I have previously taken and used to successfully cut and mig weld a fuel tank was to wash it out with water then to completely purge it with exhaust fumes. Let the exhaust fill the tank for 10 minutes or so before starting and keep it going as you work on it.
Please do your own research on this and risk assess carefully before you attempt (or even decide) to do it as the consequences of getting it wrong could result in having much more time at home looking at PH (or never looking at it again)...