In Tank FI Pump Solutions?

[Max Welton]

I'm not sure how VW joined the the upper and lower shells. Doesn't seem like spot-welds would seal.

Max

[Max Welton]

I've never seen tank shells available separately.

Max

[Ol'fogasaurus]

I've never seen tank shells available separately.

Max

I haven't either but then I have ordered other things before (my second and thicker material floor pans, for an example) and accidentally got the timing right to where I could purchase them incomplete or missing what I didn't need.

Lee

[GS guy]

I think tank halves are press-formed then robot seam welded together. The welding process somehow compresses the tank halves together at the weld seam, along the flat flange outer portion of the tank, welder rolls around the flanges while simultaneously welding the seam. Seems sort of like a spot welder on wheels!
I cut my tank in two at the outer seam, added baffles and extra inlet/outlets then welded the halves back together. Or rather my welding buddy did all the actual welding, I did all the "fitting". Unfortunately, I could not simply split the tank at the welded seam, at least not without damaging it beyond use (hammer and chisel?). I used a cut-off wheel and worked as close to the weld seam as possible to only cut through one tank half and trying to avoid cutting into the bottom half. Worked just OK, but a not easy task welding it back together. It might have been easier to cut through both halves at the weld seam and then just seam-weld edges back together? This would remove a lot of the outer flange area, creating tank-mounting problems. Opening it up was awesome for getting internal access to the tank though! Great for adding EFI internal baffling.
Jeff

[Ol'fogasaurus]

I did a search on this GS guy and you are pretty close to what I was able to find.

Adding the baffles is a really a great idea to do/have when done right (I have seen them with the lower part of the baffle strips not open enough at the bottom for fuel movement (a brain fart by someone who knew better).

I didn't see anything on metal tanks sold in halves but who knows for sure.

Lee

[Max Welton]

I would be very surprised if there were enough of a market to justify making shells, particularly for the relatively small number of type-3s remaining.

Max

[GS guy]

This manufacturing video is probably representative of how most steel tanks are made today, it shows the welding process I was trying to describe:

I used a Spectra tank for my project, purchased off Amazon.
I think if you wanted to find tank shells for a T3 you'd have to start with 2 used tanks and create (1) usable upper and lower half, cutting and grinding around the flange. Sure would be easier to work with new halves!
Are any other VW tanks at all similar to the T3? Maybe Super Beetle? Dasher? Other similar year VW offering? Maybe combine parts from different tanks to work?
I thought I was going to need a custom tank for my application (custom frame members under the tank), until I flipped the tank front to rear in the hole in the fiberglass body. It fit perfect that way! Only problem, now the top didn't work under the hood in that orientation. So off came the top to reverse it relative to the bottom, and while I was in there...
Jeff

[GS guy]

Max, again I applaud your efforts trying the bottom mount pump. That said, at this point I'd think long and hard about going top mount on your new tank. T3 parts don't grow on trees! All OEMs and aftermarket go top mount - must be a good reason. Such a large flange, in my mind, seems like it would be a real bear to 100% seal up underneath, especially long term. I'd even consider installing a (welded in) pass-through tube through the tank to get the lines out the bottom before cutting that BIG hole in the bottom of your new tank. Maybe even supply and return "stubs" welded in top and bottom? Fit submerged rated fuel hose inside connecting the tubes, with standard external fittings? The flexible internal lines would allow for some tank expansion and vibration without stressing the welds. Something to think about.
Believe me, I've "built" myself into a corner and trying more and more build-a-better-mousetrap ideas to get out, then finally backing up and re-doing it the conventional way. Hard to swallow that pill, but in the end easier to cry once and move forward that keep digging!
Jeff

[GS guy]

One option, should you consider going with the hoses through the tank idea: weld NPT bungs on upper and lower tank surfaces (where-ever convenient). This opens up many options for creating fluid passages top to bottom, and something "solid" to tighten against. Then, with simple NPT male fitting (thinking stainless here), either bore the fitting and weld in a section of SS tubing to connect hoses/fittings on either end, or use compression "bored" fittings (designed to have a tube passed through) with NPT external male threads. These are plentiful in the "brewing" market. All solid metal to metal seals (with a little sealant on the NPT threads) and little worry about future leaks. Once you have a female NPT fitting on the tank, there are LOTS of options on a through connection. If you're trying to stay tight to the top of the tank, a 90* street elbow NPT could be utilized. Bore and weld (even solder) a section of tubing to the internal-tank side to stick inside the tank. A little out of the box, much more "seal-able" than a 6" flange on the bottom!
I saw Tanks Inc. does have some bulkhead style fittings (with hose connections on either end), but again depending on a rubber ring to do all the sealing. In a plastic tank it makes sense, but on a steel tank I'd choose other options.
Jeff

[Max Welton]

Appreciate the ideas Jeff, but I haven't run out of stubborn.

This tank was not is very good shape and we did some cutting and patching. My local guy is pretty much up for anything fab-wise and did all the TIG work.

We replaced the stock sump area and had to make a bump for the bottom of the fuel gauge sender.

For the fuel pump "hat" I sandwiched a square of 22-ga between two bits of scrap in order to make clean holes. The finished panel (bolted up to the "hat" to maintain the shape) was then welded into the tank. I tested the welds with air applied to the vent tube and everything held.

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Then it was off for powder-coating.

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Max

[Max Welton]

Next I built a bracket to hold the pump where it needed to be. The hydramat needed to clear the fuel gauge sender so it's arranged diagonally.

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If it still hasn't leaked by tomorrow I'll put it in the car.

Here's a vid showing me feeding the whole thing through the hole.

https://youtu.be/WXFXJa3uyrY

Max

[Ol'fogasaurus]

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Max, keep an eye on this. Usually, a patch over a patch isn't considered to be a good idea especially when you see ripples in the materials being welded.

You are probably OK but just in case. While the idea of pressurizing for a while is a good idea add in a liquid for weight, like a full fill tank, then pressurize it a for a while just to be sure.

Lee

It is the liquid jostling around in a full tank either on the road or off-road that can make a difference. Again, you are dealing with fuel especially if it is in the front or rear of the vehicle... things can happen so be careful.

Lee

[GS guy]

Looks good Max! If that doesn't get it I don't know what would. Props for getting that pump assy into the tank- that took some finessing! Keep us posted.
Jeff

[Max Welton]

I told my welding guy that he was my enabler. I couldn't try these dumb things without him.

He said "as long as you pay me..."

Max

[Ol'fogasaurus]

Again, I was just being careful when pointing this out to you. You are probably OK with it but since I worked in much stricter controlled situation, it was my job to notice things like this.

Lee