by Chris Stevenson
Thomas Northcut / Photodisc / Getty Images
Aluminum marine gas tanks don’t last forever, as they withstand corrosion and exposure to the environment like any other component on your boat. However, aluminum has its advantages over other materials used for gas storage in marine vessels, mainly because it better fights corrosion and weighs less than other heavier metals, including some fiberglass tanks. Fuel leakage from an aluminum tank requires an immediate response, as liquefied gas and fumes pose a hazard to passengers on board. Finding and repairing an aluminum tank leak doesn’t have to be difficult and only requires a few practical steps and basic tools.
Tow the boat to a convenient job site and park the tow vehicle with the emergency brake on. Remove the safety key from the ignition. Disconnect the negative battery cable with a socket. Close the main fuel supply valve on the tank and on the engine. Use a screwdriver to loosen the gas inlet hose clamp and pull the hose from the neck of the gas tank.
Disconnect the fuel discharge line to the fuel pump with a screwdriver. If equipped with a vent hose, loosen the end of the hose or loosen the clamp with a screwdriver. Disconnect the sensor cable from the tank, if equipped.
Attach a siphon hose to the gas inlet and pump the gas into a certified container. Eliminate as much gas as possible. Use a socket and wrench to remove the strap or bracket bolts that hold your gas tank to the stringers or bottom deck. Be careful not to break the rubber mounts or insulation under the tank.
Use an assistant to help you remove the tank from the boat and place it on one end over a suitable drainage area. Drain the remaining fuel from the tank into a certified container.
Use a high pressure water hose to wash the inside of the gas tank, removing all traces of gas. Use a compressor air nozzle to force all moisture out of the tank. Place the tank at one end, allowing it to drain and air dry completely. Position the tank in a position to work on the damaged area.
Chalk an outline of the crack or corroded area, allowing an overlap of at least three inches. For a small crack or hole, use a drill and tapered bit to grind a bevel into the crack, or open the hole to produce new metal on the sides of the hole.
Use 400-grit sandpaper to sand over the crack or hole area, overlapping the area on all sides by 3 inches. For a corrosion stain, sand over the entire corroded area to bare metal and overlap on all sides by 3 inches. Put on gloves, a particulate mask, and goggles. Clean the area several times with acetone and a cloth. Dry with a cloth.
Mix the contents of the marine epoxy solder according to the instructions. Mix the epoxy agent with the hardener solution in a cup and stir vigorously. Apply epoxy welding compound to the crack or damaged area with a putty knife, using pressure to push it down into the crack or hole.
Use strong pressure to force the epoxy compound into the tank. Build several coats of epoxy solder over the damaged area, extending up to the chalk marks. Allow epoxy solder to dry and cure according to instructions.
Ask your assistant to help you put the tank back in the canister. Align the straps or brackets and insert the mounting bolts. Tighten the screws with a socket. Reconnect the main fuel inlet hose and tighten the hose clamp with a screwdriver.
Connect the fuel discharge line and tighten the clamp with a screwdriver. Replace the fuel vent hose and close the clip or tighten the clamp with a screwdriver. Reconnect the fuel tank sensor wire, if you removed one.
Refill your gas tank with the gas recovered from your containers. Check for leaks.
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