Tank surgery

 At the last car show in Newark, I bought myself a short length of fuel filler hose, just to finish off that particular job. Shouldn't be too much a problem I thought... then I got home and remembered how things sit;

Unfortunately the distance from the fuel cap location to the tank is longer than I remembered. It's also way too sharp an angle. And finally the roll bar support is in the way. Here's a better view of the issues;

Last night I had a thought about making a steel pipe to get from the tank to the filler location, but even that is not possible. So unfortunately it's going to be open surgery on the tank. Quite extensive open surgery in fact. What I did spot was a gap on the side;

There's a sufficiently large gap between the corner of the tank and the roll bar support. If I move the end piece to the side of the tank, it then becomes a shorter distance for the fuel filler pipe to travel. It's also a less severe angle to get to the filler, which means I can use the length of flexi filler pipe that I have bought.

The downside to that is I need to remove the end cap and the existing filler hole, and replace the lot with a repositioned hole. It's not going to come off without a fight so it's going to have to be a fresh piece of metal. And of course it's only thin steel to start with so that's going to be a fun task again. My wife described the tank as 'home made', and that's purely because of all the extra welds that had to be added to solve the pinprick holes! Still, I don't think any of that is a bad thing, I've got a lot more experience with welding so I might do a better job this time round. 

The last thing that is a worry is that I open up the end plate and find the tank is rusted to hell inside. This has been sat for many years, and in theory it's been sealed but water seems to find a way. Fingers crossed it's not too bad, but if not it'll be a whole new tank. I still have steel so it wouldn't cost anything other than time. I've got some 2 inch tube left over from my exhaust, it's not seamless but there's no requirement for seamless for a fuel tank. 

(Follow up from Wednesday)

So I got it cut open, and actually it's not too bad inside;

The surface corrosion is limited to the heat affected zone of the welds, and it is just surface corrosion. A wipe with a cloth gets rid of it. The edges are all rippled, but that's partly where it's welded and partly where I've taken the end cap off.

It looks really good after cleanup, the edges are pretty straight and I was able to make a template;

The lower half is the end plate with marks for folding into shape, then the top will cover the cutout section. It's marked up but more for riveting and welding.

Oh yeah, that's one thing. The metal seems to be 'pinging', IE it's going from one position to the next due to either tension or compression. That means that it's only straight in one state. So I'll need to hold it in place while I weld it. I'm thinking a series of temporary rivets will do the trick, then as I weld things into shape they will hold the surfaces together. 

I do need to insert the tube, which is the whole point of this exercise, but I also don't want to make things awkward when fitting the end plate. If I fit the tube before putting the cap on, I can get the weld done well but have a chance of warping the metal. Whereas if I cap it first then put the tube in, I can get things straighter than they were but the tube insert might then warp things. 

Either way I've got to be very careful here, I'd rather not have to go on the hunt for microscopic holes again. But I also don't want to blow through the metal as it's really thin. I might do some practice runs on spare tin just to see what I can drop the settings down to. 

(Thursdays update)

The cap is working quite well. The corners folded a lot better this time, I guess watching a whole load of random panel beating Youtube videos does actually improve things! This is the current state;

The sides are pretty tight although the plan for using some fixing rivets is still the best idea to really get things snug for welding. The tabs on each corner will be trimmed and then dressed round the tank, with rounded corners on all four sides I need to make a rounded cap. I've just noticed from this pic that I can see some paint underneath the new part, that'll have to be cleaned up before I weld. 

Talking of welding, this is my current welding setting;

So the toggle switch is at max, the rotary is at 2, and wire feed is at around 7. This works well for the steel I use, but is way overkill for this tank. Checking the manual it reckons 1mm to 1.2mm for these settings, given the fuel tank is 1mm I think that's wrong. I'm going to drop it to Max 1, with around 5 on the feed. That's good for 0.6mm to 0.8mm.

By the way, I think I might have mentioned this before, but these Clarke units are really good. While I started with an Aldi special, that burnt out after a year or so. This one I got second hand and had already lived a very long and hard life judging by the condition of it. A clean and replace of the consumables and it's alive again. The only real issue I have now is the wire feed knob, it has literally no resistance so it's really easy to knock it with the torch lead and set it too high or too low. I think a protective shroud might be useful, something to stop it turning by accident.

So the plan for tonight is to do the corners of the fuel tank, then the weekend will be welding it up and pressure testing it again. 

(Later that day)

The corners are now done;

I'm also happy with how the temporary rivet fixings are working. It's really able to clamp those surfaces together so I can get a good weld seam. Yes I have half a dozen extra holes to fill in, but that's easier than a potentially leaky seam. So that's all set up for welding, once I've had a bit of practice on some scrap.