Gas Tank Modifying and Sealing - These Fuelish Things

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 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, 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 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 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 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 (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 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, 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 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 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 hours at 60 degrees or warmer, the sealer should have a slight rubbery texture and be odor-free.

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.