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Gas Tank Modifying and Sealing - These Fuelish ThingsModifying And Sealing An Old Gas Tank From the July, 2010 issue of Rod & Custom By Kev Elliot
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It's strange how things pan out sometimes. While I've been sporadically working on the gas tank over the past few weeks, which you're about to read about, it was never intended to appear in the same issue as the fuel system in my project '49 Chevy, which you'll read about elsewhere in this issue. The two fuel-related stories effectively bookend carbureted fuel system technology, from a high-tech, pump-in-tank system equipped with a return line to a basic tank/filter/mechanical pump system. In fact, the only way this system could be more basic would be if it were a gravity feed system with no pump! 1 Here's what I started with:... 1 Here's what I started with: a Ford Anglia gas tank that I bought some 15 years ago for a "future project". That project finally presented itself, so the tank was pulled from the shelf of old rusty stuff. While working on the gas tank before finishing the rolling chassis may seem a little odd, it was a small job I could work on at my bench in my garage whenever I had a few spare minutes, and it's all got to be done at some point, right? I bought the tank, an oval-shaped item that was original equipment on an English Ford Anglia, at a swap meet some 15 years ago, though I had no particular use for it at the time. I figured it'd fit perfectly on the back of the Modified I'm building though, and once the original mounting brackets were removed, the filler neck and drain plugs cut out and the subsequent holes welded shut, it began to look pretty good. Flipping it over to hide the heavy seam that ran its full width improved things, and with a sight gauge fitted to one end, and a neat vintage-looking flip fuel cap from Crafty-B mounted in its center, the grungy old tank was looking pretty cool. But I wanted to seal the inside to ensure trouble-free use without flaky rust and debris blocking the fuel lines. 2 The original tank mounts... 2 The original tank mounts had to come off, which meant drilling out the spot welds. Lightly grinding the surface revealed where they were. The Eastwood Company is known for all manner of restoration materials and products, and their gas tank sealer looked perfect for my home-brewed budget tank resto project. While the required muriatic acid, acetone, and chemically resistant gloves aren't included (and couldn't be anyway or it couldn't be shipped), everything needed to flush, treat, and seal a gas tank up to 20 gallons capacity was delivered to my door. With a Sunday afternoon set aside for the job, which has to be completed in one session, I now have a leak-proof, old-style tank and the Modified is one step closer to completion. A Word of Warning ...
Never weld, grind, or cut a gas tank that has recently had gas in it. They can and do explode, even if they've been drained for a while. Find a specialist gas tank or radiator shop to perform the work for you or at the very least get them to thoroughly flush it so it's safe to weld on. This tank had been in my possession for so long that I was absolutely sure it had been empty for 15 years, so I felt confident in working on it. If I'd bought it recently, I'd be sourcing a specialist to perform the work.  3 Taking care not to drill...  3 Taking care not to drill through the tank itself, a Rotobroach cutter made light work of the spot welds.  4 The stock mounts are different...  4 The stock mounts are different at each end of the tank, but the same method was used to remove them. However, it was hard to locate the spot welds in this heavily rusted C-channel, so starting at one end I drilled the first weld, then used a chisel to pry the channel up, noting that where it started to bend was where the weld was. This was then repeated along the line of welds.  5 A cut-off wheel was used...  5 A cut-off wheel was used to remove the original filler neck. Obviously, cutting and welding gas tanks is dangerous if they've had gas in them recently, and I'd recommend getting one flushed and thoroughly cleaned if that's the case. This example had been empty for at least 15 years.  6 The fuel gauge sending...  6 The fuel gauge sending unit/gas outlet was removed from the top of the tank. This hole will eventually become the outlet as I elected to flip the tank over so that ugly seam (arrow) was hidden underneath.  7 Removing the drain plug...  7 Removing the drain plug revealed a little rust and I was beginning to wonder what this tank was going to be like inside.  8 With the lead melted away...  8 With the lead melted away (using a heat gun) I could see and drill out the spot welds.  9 With the base of the filler...  9 With the base of the filler neck, and some lead, removed...  10 ... I chose to enlarge...  10 ... I chose to enlarge the hole outside the damaged area and weld in a square patch with rounded corners.  11 With the repair patch...  11 With the repair patch trimmed and bent to the same curvature as the tank, it was tacked in place then seam-welded in short sections, as the tank was extremely thin and blew through in a couple of places.  12 The hole left from the...  12 The hole left from the stock drain plug was also welded closed. Compressed air was used to cool the weld between stitches and keep warpage to a minimum.  13 Kirk Brown at Crafty-B...  13 Kirk Brown at Crafty-B supplied this super-cool, vintage-style flip-up gas cap, which uses a mix of cast and polished aluminum as well as brass, for contrast and appearance. After measuring and marking the central point on what was now the top of the tank, I laid some masking tape down and pressed the cap and base, with its mounting bolts inserted, into the tape to mark their locations.  14 The mounting holes were...  14 The mounting holes were drilled (note how the new cap overlaps the old drain plug location but doesn't completely cover it) and the filler hole drilled then opened with a rotary grinder to match the size of the hole on the cap base. It was here that I noticed the central baffle inside the tank, which explained the offset drain plug!  15 The Crafty-B caps are...  15 The Crafty-B caps are normally supplied with a flat base, but I asked Brown to radius mine, as I knew it'd be going on this tank. He got it pretty close with just a phone description to go on, as you can see, and I only had to do some minimal grinding on the base to totally match the curve.  16 I bent up a short section...  16 I bent up a short section of 3/8-inch stainless steel tube and welded it on one end of the tank, drilling 3/8-inch holes in the tank first. I'll remove the middle part of what looks like a handle, and with a length of clear tubing in place, it'll serve as a gas sight gauge, eliminating the need for a fuel gauge sender and associated wiring on a tank that will be mounted totally on view. Fabricating it as one piece meant the ends would align later.  17 With the tank modifications...  17 With the tank modifications complete, I wanted to pressure test it for leaks, so I made a cork gasket for the filler cap, using a punch to form the mounting bolt holes as shown. You'll also note I "massaged' the baffle over to one side to allow the tank to be filled.  18 To access the nuts on...  18 To access the nuts on the mounting bolts I modified a short 3/8-inch wrench to suit. Well, that sounds better than saying "I clamped it in the vise and whacked it with a big hammer" right?  19 The stock sending unit...  19 The stock sending unit incorporating the fuel outlet turned out to be fortuitous as I was able to put it back in and use a blower on my air line through the old outlet to pressurize the tank. Soapy water is best to show leaks (remember fixing flats on your bicycle as a kid?) and a spray bottle of auto glass cleaner is ideal.  20 It transpired there were...  20 It transpired there were two pinholes around this patch, as can be seen from the bubbles (arrows), though the end of the tank where the sight gauge was fitted contained several, mostly around the seam where the end plate was welded to the tank. Incidentally, it didn't take much pressure before the ends of the tank started to "balloon".  21 I spent a fair amount...  21 I spent a fair amount of time trying to weld the pinholes in what was definitely the thinnest area of the sheetmetal, eventually admitting defeat and taking it to a radiator shop, who leaded over my repairs and pressure tested the tank for $25! Although I intended to seal the tank, I wanted to ensure it had no leaks beforehand. You can see here I'd also cut the sight gauge tubing. Also at this stage I scraped off the underseal that had previously been brushed on the exterior, repaired the few dents, and knocked down a couple of ridges (really edges of large depressions) as once the sealer is in and hardened, you don't want to be hammering on the tank.  22 On the left is the sealer...  22 On the left is the sealer kit as supplied by the Eastwood Company, containing Metal Wash, an etching solution, and the sealer, as well as detailed instructions. Additional items required are muriatic acid (available from hardware and building supply stores), acetone, and chemical resistant gloves for handling the acid.  23 Though hard to photograph,...  23 Though hard to photograph, you can see the inside of the tank was in pretty good condition given its age and outward appearance. However, I couldn't inspect the ends of the tank, which were the worst areas for corrosion. The old drain plug was inserted into the fuel outlet on the old sender unit (from which I'd now removed the old float to stop it from hitting the side of the tank during the sealing process) and the sight gauge tubes plugged with carburetor vacuum rubber bungs.  24 The tank was thoroughly...  24 The tank was thoroughly washed with hot soapy water, sloshing it around by shaking and rotating the tank, then a garden hose was used to flush the tank a couple of times.  25 The Metal Wash was added...  25 The Metal Wash was added to 2 gallons of hot water, repeating the previous step to ensure all internal surfaces were treated before flushing again. Though the inside of the tank, or the parts I could see at least, looked clean, the Metal Wash was a brownish color when it was poured out.  26 The Eastwood instructions...  26 The Eastwood instructions called for 3 ounces of muriatic acid to be mixed with 60 ounces of water to make a 1/2 gallon of 20:1 solution. I measured out 3 fluid ounces in a glass before mixing them. The glass was then disposed of. You don't want this going back in the kitchen cabinet! Note the use of chemical-resistant gloves. Muriatic acid is made up of about 32 percent hydrochloric acid and requires correct handling and disposal. Again, the solution was sloshed around in the tank for 10 minutes to ensure total corrosion removal, leaving the filler cap hole open to allow pressure to escape.  27 With the acid drained...  27 With the acid drained (and neutralized with baking soda) and the tank flushed twice using the hose, the Fast Etch was poured in the tank, which was then rotated slowly to allow it to contact all surfaces. This was poured out into its original container for future parts rust removal.  28 The interior of the tank...  28 The interior of the tank was much cleaner at this stage, the metal taking on a uniform gray appearance, though it looks shiny here owing to the camera flash. A quart of acetone was added to the tank next, sloshed around, drained, and then repeated.  29 After shaking thoroughly,...  29 After shaking thoroughly, the sealer was poured into the tank. I'd moved into the garage by this point as it was raining but also cold, and the instructions call for the tank, sealer, and room temperature to be above 60 degrees, though good ventilation is important too as this stuff stinks!  30 With the filler hole taped...  30 With the filler hole taped up, the tank was rotated slowly in all directions to completely coat all surfaces. The tape was then removed, the tank left to stand for 10 minutes, and then the process repeated so the excess sealer could re-coat the surfaces. This tank is so small (around 6 gallons) that I only used one of the two sealer bottles. When the tank was standing between "rotating sessions" I opted to let it stand on each end, as these were the most corroded areas. However, it's important not to let the sealer drain to one area in a thick puddle and dry.  31 Forced ventilation is...  31 Forced ventilation is required to prevent the sealer from re-flowing and puddling, as well as for thorough drying. I removed the old drain plug from the outlet, and inserted an air line fitting (the thread wasn't the same but I didn't plan on using the sender again, so I wound the fitting in!) in order to hook up my air line. Eastwood recommends a pressure of between 1-5 psi. I'd also bent the old pickup tube so the air didn't blow directly at the side of the tank.  32 Completely dry after 48...  32 Completely dry after 48 hours at 60 degrees or warmer, the sealer should have a slight rubbery texture and be odor-free.  33 While all that's seemingly...  33 While all that's seemingly left is to tackle prep and paint in order to finish the tank, not to mention some mounting bracketry, there is one further item required. The old sender had more than one use throughout the sealing process, but is now ready to be consigned to the trash. Using a hole saw I cut this disc from 1/8-inch steel, and will drill it to fit where the old sender was, as well as to take a Russell AN-8 bulkhead fitting sourced from Summit Racing. Stainless fuel line will carry the gas to the motor. And if you're wondering how I'm going to vent the tank, I plan on drilling a horizontal hole in the base of the filler cap under the hinge and running a brass or nickel-plated tube from there.
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