Plastic Fuel Tanks: Worth The Switch?

Fuel tanks can be made of either plastic or metal. While it is possible to modify a plastic fuel tank, it is not recommended. For instance, cutting a plastic tank down and resealing it is not advisable due to safety concerns. However, some people have attempted to modify their plastic fuel tanks using plastic welding, which involves using a hot air gun and a filler rod made from the same plastic as the tank. Others have suggested using a compression bulkhead fitting with a solvent-resistant rubber seal. Nevertheless, the general consensus is that modifying a plastic fuel tank is not worth the risk, and it is better to either find a tank that fits or have one custom-made.

Repairing a hole in a plastic fuel tank

It is possible to repair a hole in a plastic fuel tank. Here are some methods you can use:

Plastic Welding

Clean the area with a solvent like acetone and use a soldering iron with a sacrificial piece of plastic that matches your tank's plastic. If you can reach the hole from both sides and weld, that would be ideal, but it is not necessary. Plastic welding is a common method for repairing plastic fuel tanks and can create a strong, long-lasting seal.

Sealants and Adhesives

Some sealants and adhesives can be used to repair plastic fuel tanks. It is important to ensure that the product you choose is resistant to the contents of the tank. One option is to use a clay-like epoxy putty designed for repairing fuel tanks, such as Quick Steel or Pig Putty. Clean the tank with a solvent, roughen the surface around the hole, and then apply the putty to seal the hole. Another option is to use a product called PRC, which is commonly used on aircraft fuel tanks.

Tapping and Plugging

Tapping and plugging is a common method for repairing holes in plastic tanks. Clean the area thoroughly, apply a suitable sealant, and then screw a small sheet metal plate over the hole. The sheet metal will form to the surface and hold the sealant in place. This method can be effective, but it may not be as permanent as other repair methods.

Kits

There are also repair kits available specifically for fuel tank repairs, such as the Permatex kit available on Amazon. However, it is important to read the instructions and ensure that the kit is suitable for plastic fuel tanks, as some kits are only intended for metal tanks.

Soldering

If you have access to a soldering pen, you can use it to repair a plastic fuel tank. One approach is to use strips of a milk jug to seal the hole after soldering. Another option is to combine soldering with plastic welding by using a soldering iron to plastic weld over the hole.

It is important to note that some of these methods may be temporary solutions, and the best option for a permanent repair may be to replace the fuel tank entirely. Additionally, always take appropriate safety precautions when working with fuel tanks, as some methods may involve flammable fumes.

Plastic welding to modify a plastic fuel tank

Plastic welding can be used to modify a plastic fuel tank. However, it is important to note that this process requires careful preparation, practice, and skill. It is not a simple task and should be left to professionals or those with experience in plastic welding.

Firstly, it is crucial to identify the type of plastic the fuel tank is made of. Many plastic fuel tanks are made from cross-linked HDPE (high-density polyethylene), which cannot be welded. Therefore, it is essential to determine the material before attempting any modifications.

If the fuel tank is made of a weldable material, the next step is to thoroughly clean the area that needs to be modified. This includes removing any fuel, fuel residue, or grease from the tank. It is also recommended to flush the tank with water to eliminate any remaining fuel fumes.

Once the tank is clean and dry, the plastic welding process can begin. This typically involves using a plastic welder or a soldering iron with a gas tip to heat the plastic and create a strong bond. It is important to use the correct type of plastic welding rod that matches the material of the fuel tank. The welding rod should be softened and forced into the parent material, creating a clean and even ribbon of fused material on both sides of the weld.

It is also recommended to add a strengthening agent, such as a steel screen or mesh, to the weld area. This will help reinforce the repair and ensure its longevity.

After the welding is complete, it is crucial to test the tank for leaks. This can be done by filling the tank with water and checking for any signs of leakage. If leaks are detected, they can be repaired by reheating the area and adding more welding material.

While plastic welding can be used to modify a plastic fuel tank, it is important to approach this task with caution and ensure that all necessary safety precautions are followed.

Using a sealant to fix a plastic fuel tank

Using a sealant is one of several methods to fix a plastic fuel tank. The process involves first draining the tank of any gasoline and allowing it to dry. Next, the area around the hole or crack should be sanded to create a rough surface for the sealant to adhere to. It is also important to clean the area with a solvent such as acetone, rubbing alcohol, or soapy water to ensure that the sealant will bond effectively.

Once the area is prepared, a suitable sealant can be applied. One option is to use an epoxy glue, which is available in a two-part mixture. The epoxy should be applied around the perimeter of the opening, and a fiberglass patch can be used to cover the hole and overlap onto the surrounding area. More epoxy is then applied to the patch and the surrounding area, pressing firmly to saturate the patch. This method creates a strong bond and can be sanded smooth once dry.

Another option is to use a plastic welder, which can be purchased or rented. Plastic welding rods made specifically for this purpose are used to fill in the crack or hole. It is important to start at the edge and run the bead completely around the opening before crossing over to ensure a complete fill. Once the weld has set, it can be sanded smooth if needed.

A third method is to use a soldering gun, which involves heating up the plastic around the crack to create a trench and then laying a plastic patch over the area while the plastic is still soft. The soldering gun is then used to smooth out the plastic and fuse the patch in place. Once cooled, a two-part epoxy glue can be applied over the patch for added strength.

It is important to note that not all sealants are suitable for use with plastic fuel tanks. Some products, such as Flex Seal, are not designed to withstand heat, pressure, or flammable liquids like gasoline. It is crucial to choose a sealant that is specifically recommended for use with plastic fuel tanks and always work in a well-ventilated area to avoid inhaling fumes.

Using a hot air gun to modify a plastic fuel tank

Preparation:

Before using a hot air gun on a plastic fuel tank, it is crucial to ensure that the tank is made of a suitable plastic that can be welded. Softer plastics, such as those used in bumpers and dash binicles, are more amenable to welding than harder plastics like those found in water manifolds. Identify the type of plastic your fuel tank is made of and research its weldability. Additionally, ensure that the tank is properly ventilated and has not contained fuel for a significant period, reducing the risk of fuel vapour accumulation.

Equipment:

For the modification process, you will need a hot air gun, preferably electric to avoid naked flames. A gas soldering iron tip can also be used but is less ideal due to the open flame. You will also need personal protective equipment, including gloves and eye protection, to safeguard against any potential hazards. Ensure you are in a well-ventilated area to dissipate fumes.

Execution:

When you are ready to begin, use the hot air gun to heat the plastic fuel tank until it becomes pliable. The plastic will start to turn transparent as it reaches the appropriate temperature for welding. Be cautious not to overheat the plastic, as it can melt through. Once the plastic is pliable, use a piece of wood or PVC pipe to shape it. For more complex shapes, you may need to use a glove to manipulate the plastic. If you need to join two pieces of plastic together, use a sacrificial piece of plastic from the tank or a similar plastic as a filler rod to create a strong weld.

Cooling:

After shaping or welding, use compressed air or a spray bottle with water to cool the plastic rapidly. This will help set the shape and prevent deformation. Be cautious not to use excessive force when cooling, as the plastic will be more fragile when heated.

Safety:

Working with fuel tanks and hot tools presents several hazards. Ensure you are in a well-ventilated area and take steps to prevent ignition of any fuel vapours. Avoid using a propane blow torch, as the intense heat can easily split the tank open. Always wear appropriate protective gear and be mindful of the potential risks involved.

Using a plastic tank for diesel fuel storage

Plastic fuel tanks are a common alternative to metal tanks for diesel fuel storage. They are often made from polyethylene, a durable yet malleable form of plastic. Specifically, industrial-grade plastic drums are made from high-density polyethylene (HDPE), which is designed to hold industrial goods.

There are several benefits to using a plastic drum for diesel fuel storage:

• Plastic drums can be safely used to store diesel fuel for up to six months.
• Diesel fuel degrades quickly when it comes into contact with certain metal alloys, such as zinc or copper. Plastic drums do not have this issue.
• Metal drums are prone to rust, which can affect the quality of diesel fuel. Plastic drums do not rust.
• Plastic drums are robust, cost-effective, and can be stored and transported industrially.
• Leakages in plastic drums can be easily repaired, and maintenance costs are low.
• Plastic drums can be recycled or decontaminated, repaired, and reused.

However, it is important to note that not all plastics are suitable for diesel fuel storage. Before using a plastic drum, ensure that it is designated as suitable for use as a plastic oil drum and that it is made from HDPE. Additionally, diesel fuel should not be stored in a plastic drum for longer than six months, as the diesel will react with the plastic polymers over time, leading to leakages. Extreme heat or temperature changes will also degrade the fuel faster.

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