19 replies to this topic

[leepol83]

Hi chaps I recently bought a right hand fuel tank I want to have it painted so it looks nice in the boot however it's not perfectly flat it has lots of big dents,well I say dents I think it's just How it's been made to be honest. what's the best way to straitened it out I fear if I use filler it will just crack when it's filled with fuel any tips would be greatly appreciated.

[antcole]

Id have thought filler would be no problem as long as the surface is properly 'keyed' and is back to bare metal.
Surely the tank doesnt swell that much when its full of fuel?

[minidaves]

key it and sand it just ofcourse as its a fuel tank, u should not use electric tools on it.

[leepol83]

Cool thanks chaps appreciate it

[leepol83]

Hi chaps just been looking at the tank looks like it could be as thick as 5 mm in places how about if I latyer it up with fiberglass matting and resin would this have any effect in the tank it's self

[jonny d]

can you suck out most of the dents with a panel sucker

[leepol83]

I've tried the panel sucker but just pops back in again
Cheers buddy

[tiger99]

Is the tank new, and therefore never had any fuel in it? If you are sure about that, you can be a bit more adventurous. Pressurising very gently with air may pop the dents out permanently. Don't go above anout 1 or 2 psi!

Or, pressurise with an inert liquid.

If you do decide that, as a last resort, you have to fill the dents, body solder (commonly called lead but legally it must be lead free now) will not crack and fall off if the tank flexes. No problem on an new tank, just get the metal bright and shiny, apply flux, tin like any other solder job. Plumbers solder is just as good for jobs like this. If it is lead free you can sand it down with a DA sander or whatever you use on bodywork, but if lead is involved you must use hand tools only.

If the tank has contained fuel, you will need to clean the metal by hand, not using any tools that will produce sparks, and apply the solder with a very large electric soldering iron, not any form of blowtorch. As an added precaution, fill the tank with argon or C02, whichever you use for welding.

[tiger99]

Oh, yes you can! In fact a really big iron works tolerably well on general bodywork too. With practice you can partially remelt the solder without it all wanting to run away. But I am talking about a monster iron, not anything that you might use on electrical work.

http://www.spotweldi...heavy-duty.html

That is a US site, so they are probably all 110V, and likely don't meet UK safety rges anyway, but the biggest one, 550 watts, would do a fine job. Google will find a UK model, I am sure.

Old fahioned plumbers solder is quite workable, the lead-free version slightly less so, but still adequate for filling minor dents. The lead-free stuff is lighter, which is good. Actually, it is mostly tin, with usually copper and silver added to lower the melting point.

[Shifty]

I don't like where this is going, well the bits about doing hot work on a petrol tank anyway.

If the tank was dented then compressed air could push the dents out, but I'm assuming that the dents are just left over from the pressing of the tank? If this is the case then all you can really do is use filler and try and make it look pretty.

[Shifty]

That I don't doubt but I'm not too keen on recommending it to other people. I've heard of people welding them by rinsing/cleaning and then connecting to a car exhaust to flush though whilst welding as the carbon monoxide reduces the explosion risk.

[Noah]

Depends on how big the dent is but as above,

If its had fuel in it, ever.

No Sparks, No Flames. Other wise you'll end up crispy.

I'd just filler and paint.

[Alex_B]

I wouldnt bother to be honest if its how its been pressed I would just fit and forget as there is only one side visable when fitted and you could board out the boot anyway?

[tiger99]

Oh, you will not be able to tin the metal, with or without a soldering iron, if the tank is full of water. But if empty, or full of inert gas, you just clean and flux it, and apply a blob of solder to the iron, to help make good thermal contact with the tank. Apply the iron to the tank, and as the flux melts, rub over the area with your stick of solder. The white plumbers flux used with lead-free solder is nasty stuff, so it needs to be washed off afterwards, and don't dip your finger in it! The old brown flux, used with lead solder, was less harmful.

You could of course use fiendishly expensive solder paste to make the tinning easier, but why waste money?

[sam7]

whats wrong with just using filler!!!!!! its not a very hard decision!!

filler will flex a hell of a lot to cope with the expansion of the tank. it will stick to the metal on the tank just like it would on a body panel. so u wont have any problems unless you havnt rubbed it down properly or have dents that are about 3 inches deep?? which u definatly wont have!!