I will be fabbing a fuel tank soon for my 34 coupe, (I built one for my 31 coupe out of 2.5mm alloy several years ago - tested and certified as per engineering guidelines for registration) this one will be made out of cold rolled steel 1.6mm thick, I plan to use a external fuel pump, I have a universal sender unit. The tank will be baffled and tig welded etc. I am after any advice / tips from others who have built a fuel tank e.g. the use of a tank sealer like POR 15 etc - is this necessary. Thanks in advance, Glen
I used POR 15 on a custom aluminum tank, after a few years, the POR 15 sealer was flaking off inside the tank. Had to change out the tank
Since you have done it before and it gets checked, you have more experience than many. I'd try to avoid a sealer. If concerned with rust, could you include a top plate large enough to allow a powder coat or other coating that would seal but wouldn't flake? I'd ask the engineer!
Only asking about POR 15 after watching a youtube video where a guy who fabbed a steel tank used it, I was not going to use any sealer when I initially planned to build this tank. I was going to use alloy again but decided on steel as I had some cold rolled 1.6 mm lying around. I am not to concerned about rust as this hot rod will be used on a regular basis. I also thought about all the cars manufactured with steel tanks from the factory. Thanks again for your input, Glen
Factory steel tanks are or were made from terneplate. On the other hand; I've made several tanks out of plain old cold roll steel with no problems. Far as coatings; usual story heard is they failed.
aren't factory steel tanks galvanized? I would think that the alcohol in todays fuels would absorb water and rust the hell out of the inside of a steel tank. I would build it out of aluminum or stainless
I built the one under my '37 out of cold rolled, wasn't smart enough to know any better. I welded with a mig welder, two baffles inside, 14 gauge steel. It was tough to bend, but easy to weld being so thick, thought the 14 gauge would hold up better if it was rear-ended. No sealer, had it out a few years back, it had very little rust inside on the top where the fuel splashes, bottom and sides were still clean steel. It's been in the truck since 1999. Took four or five pressure tests with soapy water to get it all sealed.
I have built a number of them when I was playing with off-road rigs. I was generally using 10 gage plate, but I would lightly sandblast or sand with a 36 or 80 grit flap disc on the side that was going to be used inside the tank before fabbing things up. I figure that gave it a bit of "tooth" for adhesion. Then I would seal the tank when finished with a gas tank sealer from Northern, the same outfit that makes radiators and such. It is blue, and sets up a bit harder than any other sealers I have seen. I haven't had any issues with that stuff whatsoever as far as adhesion or degrading go, and some of those tanks were pretty much used as a skid plate at times, and had some good scars on them. I have seen other sealers that stay soft or rubbery, and those seem to be the ones that turn into a "bag" and cause trouble. I have bought it through a local radiator shop before, as well as Summit. I see Speedway has it too: https://www.speedwaymotors.com/Gas-...MIqIaUy__kjwMV2xFECB3mNwm1EAQYASABEgKZQ_D_BwE
The surface tension of gasoline is much lower than water. What this means is that gasoline will seep out of any tiny pinholes in your welding. Far different than water. Hopefully there are none. If there is a tiny pinhole or 2 don't use tank sealer. Look for a tube of Seal-All and use a tiny dab on the spot and try to force it in there best you can. You can actually seal a tiny leak from the outside too. Forget JB weld or similar. Seal-All works great and you don't have to deal with tank sealer problems.
If you make your own tank out of steel and use a sealer, make sure the sealer can handle the new ethanol blend gasoline. I have two homemade steel tanks in which I used Bill Hirsch tank sealer. I think the preparation of the inside is super important to get good adhesion of the tank sealer. In the first tank I made I had used clean cold rolled 16 gauge steel. That one has held up fine. In the second tank, I used hot rolled steel (which has a thin layer of grey mill scale on it). After about ten years the sealer in the hot rolled steel tank sort of shriveled up and came loose from the inside, and some bad gas full of moisture corroded the hell out of the inside of the tank once the bare steel was exposed. The rust, mixed with decomposed fuel deposited a thick layer of black sludge that looks like asphalt and clogged up the whole sump area completely. Nothing dissolves that black sludge, not even acetone or carburetor cleaner. After two weeks of trying different things, I gave up and put the old tank on the shelf and bought an aluminum tank. Ethanol blend gas is a pain in the ass and wrecks everything over time. I also had to replace the rubber diaphragm in my fuel pressure regulator because the ethanol in the gas had turned the soft rubber diaphragm into a brittle cracker, so that it stopped regulating the pressure. By the way, a Rochester tri-power setup (2G+2GC+2G) really likes 4 psi. Any higher than about 4.5 psi and the fuel bowls overflow from the vents and dribble gas down the throat of the carbs, which makes for horrible fuel mileage and a really rough idle.
I have fabbed a fuel tank for a turf machine and plan on doing one for my roadster build. If your diligent with the TIG you won't need to use a sealer. I also think having a good design and well thought out plan is key..................try to think of everything i.e. sealing the sender, tank access, venting the tank, plumbing the pump supply, how it's mounted to avoid chafing from movement etc. I have seen fuel cells where the pick up is located towards the rear (and low) of the tank. I freshened the fuel tank in my '64 Ranchero and thought it was all fairly simple though - it was galvanized or zinc plated. I renewed the sender, and the fuel pick up plumbing was part of the sender unit and the fuel pick up had a filter on it. I would also add beads to the sheet metal to stiffen the tank walls. All stuff to consider
From my off-roading experience, and as you have suggested, Aussies are subjected to pretty intense certifications when modding vehicles. I have a 167L Long Ranger tank from Australia installed in my off-road rig and got it second hand. Exterior was pretty crusty, but interior was absolutely mint. It was made from steel and I believe it wasn’t coated.
Maybe use "Zincanneal" sheet, it's very formable and has a zinc protective coating other than where you'll weld it. Build it with lapped corner joints if possible for improved rigidity. Try to condition any accessible internal welds with a Phosphoric acid type metal conditioner. https://en.enzymecode.com/news/the-effect-of-phosphoric-acid-on/ Alternatively make it from 304 or 316 S/S and then have NO corrosion fears
Thanks guys for all the advice / tips, I've got a lot to think about before I start, mainly the use of alloy or steel, I am not to concerned about the sealer - seems like it may be more trouble down the track. Anyway keep the advice coming as I plan to start in about a weeks time. Glen
If you are building a brand new tank I would avoid the sealer. Back in the early 70's I used sealer and when the ethanol gas came along it gave me nothing but trouble. I know the new type sealer is impervious to the ethanol gas, but who knows what the future brings? As far as your new tank you seem to have all the bases covered. I would also provide a threaded bung for a drain plug.
If the shape is rectangular, I’d check out ATL or Fuelsafe for a real fuel cell. They can also make bladders for a canister or vintage fuel tank, and the bladders will stand up to any fuel you will experience on the street. Spendy? Yes, but safe and won’t leak.
Thanks for all reply's, I have decided to build an alloy unit, I purchased some 3mm / 1/8 alloy sheet, after working out basic design I folded sheet and made some mounts, still in the early build stages. My plan is to mount to one side and put battery next to tank in its own similar looking alloy box, tank will have a sump with 2 x AN 8 fittings, I will be using a electric pump with a return line etc. A few pics, Glen
When you weld on the ends roll every edge with a slight radius so that your welds are more like butt welds instead of corner welds. that will make fit-up easier and reduce distortion and produce a generally more professional look.
Ethanol is a corrosion inhibitor at all but the tiniest concentrations. Also, ethanol will stop absorbing water from the atmosphere once the water reaches around 4% of the alcohol volume. There is research that suggests aquaeous E90 is a lovely performance/everyday fuel, but the only way to make it is to add the water on purpose. The problem is where we get mixtures with a three-way miscibility situation, i.e. ethanol — water — petrochemicals. That changes with temperature, and miscibility matrices exist for various blends. The problem with low-ethanol blends is that the temperature where the water ceases to be miscible with the rest is within the ambient range you're likely to see. You might have a stable mixture in the afternoon, but by midnight water has separated out, and that can cause corrosion if oxygen can get at it. As long as the water stays in solution, it isn't a cause of corrosion. Higher-ethanol blends will only separate at much lower temperatures. The problem isn't the ethanol as such. It's having ethanol and water-insoluble petrochemical compounds together at the same time, and more of the latter than the former. Most vodka around here is pretty much aquaeous E43, and we know it stays in solution in the freezer. The alcohol should make it possible to mix it with vegetable oil, if it's warmed up a bit. It'd be interesting to see how much oil you could mix in at different temperatures. Alcohol-petrochemical mixtures can do crazy things. E100 is considerably less volatile than most petrochemical fuel components, but mix them together and the result is more volatile than either on its own. Again, the low-ethanol blends are worse.
I wonder how practical it would be to make a tank by the very early method of double-seaming and soldering. I rather like the visible seams around two faces. Edit: I came across this: https://www.eaa.org/eaa/aircraft-bu.../fuel-systems/how-about-an-aluminum-fuel-tank
A few pics of todays progress, fabbed up tank baffles and machined fuel sender unit bung ( I paid $45.00. for a sender mount kit but ended up making my own as mount kit was fucking useless ). I need to practice my alloy welding as its been a while, approx. 3-4 years since I welded aluminum. Glen
I used an HQ panel van tank (modified) in my ICV I registered in 2013 with Por15 sealant and it's still going strong. I also used in my Son's MightyBoy tank and that's been going for 8 or 9 years. If prepared properly and the instructions are followed to the letter it works well.
Thanks for reply, I used POR 15 for my 31 chassis - I followed instructions to the letter with excellent results. I have decided to use aluminum so I don't have to use an inside coating, my 31 coupe has an aluminum tank and has been on the road for 5 years without issues, thanks again for your input. Glen
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