Aluminum Vintage Fuel Tanks: Safe For Outboards?

Vintage outboard fuel tanks are a hot topic among boat enthusiasts, with many forum discussions dedicated to their maintenance and repair. These tanks, often referred to as pressure tanks, were used on various models of outboard motors from the late 1940s to the early 1960s. While the material composition of these vintage tanks is not explicitly mentioned in the sources, the primary focus of this paragraph is on the construction and functionality of these tanks. However, it is worth noting that modern fuel tanks for outboard motors are available in both aluminum and plastic variants, with each material offering unique advantages and considerations.

Advantages of aluminium fuel tanks

Aluminium fuel tanks are advantageous for several reasons. Firstly, they are extremely durable due to their corrosion resistance and ability to withstand harsh outdoor elements such as heat and dust. This makes them ideal for marine applications as they can withstand constant exposure to saltwater, which can quickly degrade other materials. Aluminium is also lightweight, strong, and anti-corrosive, making it a preferred choice over stainless steel for fuel tanks. The longevity of aluminium fuel tanks is further enhanced by their resistance to dents and punches, which can affect the appearance and form factor of the tanks over time.

Another advantage of aluminium fuel tanks is their customisability. The malleability of aluminium allows fabricators to craft fuel tanks that precisely fit the unique space constraints of each vessel. Additionally, aluminium is easily cut and welded, making it a preferred material for industries seeking spacious fuel tanks for automotive and marine needs. Aluminium fuel tanks can also be treated with a protective polymer coating, further enhancing their resistance to oxidation, tarnishing, and staining.

Aluminium fuel tanks offer peace of mind to captains and crews alike due to their ability to withstand intense forces at sea without leaking. This is attributed to the high-density properties of aluminium coupled with its low melting point, enabling it to endure the fabrication process while maintaining its ability to resist water damage. Furthermore, the use of aluminium fuel tanks can contribute to cost reduction, as they are lighter than steel tanks, leading to potential fuel efficiency gains.

In summary, aluminium fuel tanks offer a range of benefits, including durability, corrosion resistance, customisability, and weight reduction. These advantages make aluminium a popular choice for fuel tanks in various applications, particularly in the marine industry, where its resistance to saltwater degradation and ability to withstand intense forces at sea are highly valued.

Repairing vintage outboard fuel tanks

Vintage outboard fuel tanks made of aluminum are susceptible to corrosion and environmental damage, which can lead to fuel leaks. It is crucial to address these issues promptly to ensure the safety of passengers. Here is a comprehensive guide on repairing vintage outboard fuel tanks:

Step 1: Prepare the Work Area

Before commencing the repair, find a suitable work location and park the boat. Disconnect the negative battery cable, shut off the main fuel feed valve, and remove the lanyard key from the ignition.

Step 2: Disconnect Fuel Lines and Remove Fuel

Disconnect the gas intake hose clamp, fuel discharge line, and, if present, the vent hose. Use a siphon hose to pump out the gas into a certified container. It is crucial to remove as much fuel as possible to ensure safety during the repair process.

Step 3: Remove the Fuel Tank

Detach the tank from the stringers or bottom deck by removing the strap or bracket bolts. Carefully lift the tank out of the boat with assistance and set it over a suitable drainage area to remove any remaining fuel.

Step 4: Clean and Prepare the Tank

Utilize a high-pressure water hose to thoroughly clean the inside of the tank, ensuring the removal of all fuel traces. Then, use a compressor air nozzle to eliminate any residual moisture. Set the tank aside to air dry completely. Identify the damaged area, including cracks, holes, or corrosion spots, and mark an outline around it with chalk, allowing for a three-inch overlap.

Step 5: Repair the Damage

For small cracks or holes, use a drill and conical bit to widen the area and expose new metal. If there is corrosion, sand over the affected area and its surroundings with 400-grit sandpaper until you reach bare metal. Ensure you wear protective gear, including gloves, a particle mask, and goggles. Clean the area with acetone and a rag, and then dry it thoroughly.

Step 6: Apply Epoxy Weld

Following the manufacturer's instructions, mix the marine epoxy weld compound. Using a putty knife, apply the epoxy weld with pressure to force it into the cracks or holes. Build up several layers of the compound, extending beyond your chalk marks. Allow the epoxy to dry and cure according to the specified directions.

Step 7: Reinstall the Fuel Tank

With assistance, carefully place the tank back into the boat, aligning the straps or brackets. Secure the tank with the mounting bolts and reconnect the fuel lines, vent hose (if applicable), and fuel tank sensor wire.

Step 8: Final Checks

Refill the gas tank with the fuel removed earlier and carefully check for any leaks. Ensure that all connections are tight and secure.

It is important to note that this repair process requires careful adherence to safety precautions. Do not work near any smoking or ignition sources, as even slight fumes can be a potential hazard.

Differences between vintage and modern outboard fuel tanks

Vintage outboard fuel tanks differ from modern ones in several ways. Firstly, vintage outboard fuel tanks often utilised pressure tanks, which used air pressure to force gasoline through a hose to the engine, while modern outboard fuel tanks typically use fuel pumps to draw fuel through the hose. Vintage pressure tanks had attachments for two hoses, usually with one labelled as "fuel" and the other as "air", and they lacked a vent due to being pressurised. Modern fuel tanks, on the other hand, have a single fuel line and a squeeze bulb for manual priming.

Vintage outboard fuel tanks also varied in terms of their compatibility with different outboard motors. For instance, the Mercury pressure tank was used for specific models like the Mk-15 and Mk-20 from 1953 to 1955, while the Champion tank was compatible with a range of horsepower motors from 1953 to 1958. The hose connections on these vintage tanks could differ, with some having a single outlet and others featuring separate "air in" and "fuel out" ports.

The construction and design of vintage outboard fuel tanks also set them apart from modern ones. The vintage pressure tanks often had large, removable tank tops, usually painted black, and the hose was typically clamped to the tank without a quick connector. The caps for these pressure tanks were unique and hard to replace. Additionally, the quick connector that attached the hose to the outboard was also a rare and expensive piece to find.

Vintage outboard fuel tanks were made of materials such as aluminium, brass, and steel. They were often painted or had a natural metal finish. The tanks could be cylindrical, rectangular, or sometimes customised to fit the boat's shape.

In summary, vintage outboard fuel tanks relied on pressure systems, had unique hose connections, and were constructed with different materials and designs compared to modern fuel tanks, which favour fuel pumps and standardised connections.

Collectors' interest in vintage outboard fuel tanks

Vintage outboard fuel tanks are a sought-after item for collectors, with enthusiasts scouring flea markets and online auction sites for rare models. These fuel tanks are often made from metal, with some older tanks made from aluminum. The tanks come in various sizes, from 3-gallon to 6-gallon capacities, and were used for different outboard motors, such as Johnson, Mariner, and Mercury.

The age and model of these fuel tanks are of particular interest to collectors. For example, a vintage Johnson outboard 6-gallon metal gas tank is likely from the 1950s, while a Champion tank with a single outlet could be from the 1950s or 1970s. The Mercury tank, with its "air in" and "fuel out" ports, was used from 1953 to 1955 for the Mk-15 and Mk-20 models.

The condition of the tanks is also important to collectors. While some tanks may show signs of cosmetic wear, they are often still fully operational and functional. Collectors are willing to pay a premium for tanks in good condition, especially those with rare or unique features. For instance, the pressure tanks and fittings for Mercury outboards are considered valuable by collectors.

The scarcity of certain models also drives up their desirability among collectors. A very rare vintage Mariner outboard fuel tank with a 3.7-gallon capacity is one such example, attracting a lot of interest from collectors. The availability of specific parts, such as fuel connectors and hose hook-ups, can also impact the value and appeal of these vintage outboard fuel tanks.

Overall, the interest in vintage outboard fuel tanks among collectors stems from their age, model, condition, and rarity. These tanks represent a bygone era of outboard motors and can be a valuable addition to any collection, with enthusiasts always on the lookout for unique and well-preserved examples.

Cleaning vintage outboard fuel tanks

Vintage outboard fuel tanks are often made of aluminum. Before cleaning, it is important to determine the material of your tank, as alkaline cleaners can eat away at aluminum.

Step 1: Drain the Tank

Firstly, you will need to drain the tank. If you have a removable tank, simply empty out the gas. For fixed tanks, use a gas siphon. Remove the fuel cap and plug any vent piping. Place the hose into the gas tank and put a chemical-safe container under the other end. Pump the siphon and allow the gas to drain. Remember to dispose of the old gas properly as it is toxic.

Step 2: Disconnect the Fuel Line to the Boat Engine

Before adding any cleaning chemicals, disconnect the gas line to prevent any damage to the motor. Every boat is different, so check your manual for specific instructions.

Step 3: Clean the Boat Fuel Tank

Now it's time to start cleaning. You can use a pressure washer on the lowest setting to blast water into the tank and remove dirt, grime, and debris. Keep blasting until the water runs clear. Alternatively, you can use a specific fuel tank cleaner or isopropyl alcohol to remove sludge. Pour in about 3/4 of a can of cleaner or fill the tank 2/3 of the way with alcohol. Let it sit for 15 minutes to several hours, then dump or siphon the liquid into a chemical-safe container.

Step 4: Check and Change the Fuel Filter

Check your fuel filter and other parts such as gas lines, intake valves, gas caps, and floats for any debris. Use carb cleaners or specialized cleaners to remove debris and wipe down the parts with a lint-free cloth.

Step 5: Dry the Tank and Reattach Hoses

Use a lint-free towel to wipe down the tank and other parts. If the tank is removable, leave it to dry in the sun for a few hours with all openings uncovered. Finally, reconnect the fuel lines and other parts, and remove any plugs in the vents.

Additional Tips:

• Put the boat on a trailer if possible.
• For fixed tanks, angle the boat so the gas moves to one side of the tank.
• Always wear protective clothing and gear when dealing with gas, and ensure the area is well-ventilated.
• Regularly clean your tank to avoid thick sludge and buildup, especially when you know the boat will be unused for a while.
• For large boats or if you don't feel confident, contact a marine professional in your area.

Happy cleaning!

Frequently asked questions