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Modifying a petrol tank


sheeppimp

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I have a petrol tank mounted in the rear bed of the 80in and I want to separate it a little from the cabin space for obvious reasons. My thinking was to 'simply' put in a false floor running across the top of the wheel boxes. This would have the added bonus of providing extra separate space for tool/spares/junk etc.

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however, perhaps predictably it doesn't look like it's going to be that simple as the filler neck sits above the wheelboxes

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Either I buy another tank, which is probably going to have to be custom made as every tank I have looked at so far is too deep, or modify the filler neck. there's nothing wrong with the existing tank and since modifying it is probably the less spendy option I'm currently leaning that way but not sure how to do it safely what with explosive petrol vapour and hot metal? Any suggestions?

Alternatively has anyone got a tank that might fit, max height including filler is 20cms

Cheers

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If you plan on grinding/welding it, there's emptying/purging procedures to follow. something along the lines of draining it, leaving it to properly 'dry out' and then purging with inert gas.

someone else has probably got better advice though.

The other option would be to make the false floor thick/high enough so the filler sits flush, in a hole in the floor, though that would contradict the whole cabin seperation idea.

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Could you recess the floor so that it sits lower down. It would help keep the tank in place at the same time.

Les.

short answer is don't know, hadn't thought of that option so haven't looked :)

It's bolted down at present (you can just see in the top picture) so movement hasn't been an issue to be honest. I could just put the floor in so it sits above the wheel box by 50mm, but that results in dead space and being an 80in I don't like that idea so much, kinda want to retain as much usable space as possible.

I was wondering about the possibility of an 'aircraft' stylee flush filler cap?

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I think unless you are prepared to cut your bodywork about to fit an external filler it may be worth just boarding over level with the seat boxes, leaving a hole for the filler to poke through. Then box around the filler, allowing a hinged access flap to open to put fuel in. That way you reduce the fumes and risk of fuel spilling on you in an accident for the least effort and chopping things about.

Giles

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I cut a section out of and modified both my 16 gallon tanks to make room for belly wheels (another storyfor another time) and I am still here fuly functional and intact :rolleyes: I first filled the tanks with water, leaving about a litre of air spaceat the top. Then with an acetelene torch I burnt the fumes that were vaporising through the filler tubes for a couple of minutes. There were no bangs or explosions. After I was satisfied that most of the fumes were burnt off I topped the tanks back up full with water, sealed the filler and breather tubes with bungs and tape, turned the tank uside down and cut the section out with angle grinder and cut off disc. I temporarily filled each cut with bathroom silicon sealer to retain the water so that I could turn the tank over to cut the other wall. Once I completed the cut I fired up the torch again and burnt off the fumes before removing the cut out section. There were some fumes but so long as the air volume is kept down to a minimum, violent explosionswon't occur. i filled in the cut out section to the revised shape by siliconing and taping the filler panel in place,just leaving one plane clearfor welding refilling with water but leaving justenoughair volume to permit localised heating for oxy welding. The welded sections took about half hour each to weld up and during that period Icould feel and hear only minor popping as the remaining fumes ignited.

Bill.

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I emptied my tank then thoroughly pressure washed and drained it three times over, til there was absolutely no smell of petrol then filled almost to top with water then took the grinder to it, no bangs. Flushed again several times and airline to get the grindings out.

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Better than just venting it, get the tank steam cleaned - ten minutes of thorough 'internal inspections' with the lance on maximum and there'll be naff all left to even smell. If you want to fill it with water or argon fill it afterwards so much the better but it'll be worth the beer money just for the peace of mind of the rest of us!

AndyG

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nice one, cheers for everyone's replies a little more confident about this one now. just in case i'll make sure the camcorder's running so if it does go bang you can all see. :o

... and you'll get £250 from Germy Beagle on the "It shouldn't Happen To A Welder Video Outakes Show" :-)

AndyG

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