If you need to handle the tank before it finishes cooling, wear heat-resistant gloves. However, avoid attempting to drain hot fuel out of the tank.

Park on solid, flat ground before attempting to lift the car. Make sure it’s stable on the jack stands before you crawl underneath it. Do not get below a vehicle if you are unsure that it is safely supported. Unless the gas tank has already been removed from the vehicle, you can’t repair it without getting underneath it. Most leaks are visible from the underside and can easily be patched up. If you’re fixing an accessible tank, you won’t have to use jacks. For example, jacks aren’t necessary for motorcycles or lawnmowers. Many vehicles’ fuel tanks can be accessed from inside the vehicle. Check your vehicle’s set up for how to access the top of the fuel tank.

For example, if you’re trying to drain a car’s fuel tank, the drainage valve is on the underside. Jack up the car, then pull the valve out to drain the fuel.

Note the size of the leaks as well. Epoxy is fine for cracks and small holes. If the tank has holes more than 1 to 2 in (2. 5 to 5. 1 cm) in diameter, try welding instead.

Removing a gas tank is often difficult work. If you’re dealing with a leaking tank on a vehicle or another device, consider using epoxy putty for the repair. It can often be applied without removing the tank. For other devices, such as lawnmowers, refer to the owner’s manual for specific instructions on how to detach the tank. They tend to have clips and bolts that are easy to remove with a socket wrench.

Note any rust or stubborn stains on the tank, especially if they are near the leak. You may need to flush out the tank several times in order to eliminate all debris. To ensure the tank doesn’t ignite, make sure it no longer smells like gas. If it still smells, wash it again. You could also use a gas detector to check for lingering gas fumes.

If you’re fixing a metal tank, scrub it until you see bare metal. You could switch to rougher sandpaper, such as an 80-grit piece, if you’re having trouble removing tough stains.

If the tank doesn’t look clean at first, apply more rubbing alcohol or degreaser. You may need to scrub it a few times to prepare it for the repair. If you don’t have rubbing alcohol, you could get a commercial degreaser like WD-40. They are available online, and most auto part stores and hardware stores also carry them.

Make sure you’re using a type of putty that matches the gas tank you want to repair. Regular epoxy putties are for plastic tanks, and there are specific products for metal tanks. Some types of putty don’t require mixing. All you have to do is knead it to the proper consistency.

For small repairs, try cutting off a 1 in (2. 5 cm)-long chunk of putty with a ruler or knife.

Try to get the putty to blend in with the tank as much as possible before it has a chance to dry. Use more putty as needed to cover the area. To reinforce the putty, you could cut a fiberglass mesh patch, place it on the leaking spot, and then cover it with more putty.

Avoid using the tank until the putty has fully cured. Once it has dried, refill the tank and check it for leaks again.

Your tank may leak before a year is up, or the epoxy seal could last longer than that. It depends on the application and the tank’s condition. It also can weaken faster if you use the tank often. For a more permanent fix, either weld the tank shut or replace the tank entirely.

You could order welding rods online or from a hardware store. However, some places let you rent out the tools needed for the repair. If you’re unsure what kind of welder and rod to use, take the tank with you to a hardware store. Ask the employees for advice.

Aluminum tanks are much lighter than steel ones. If the tank seems unusually heavy, then you will most likely need a steel rod to fix it.

Ventilating your area is also important. Work outdoors if you are able to. Otherwise, open up nearby doors and windows. Keep other people and pets out of the room until you’re done with the repair. Have a holster or base to place a hot welding gun until it has had a chance to cool off.

If you’re using a metal stick welder, the stick fits inside the welder so you don’t have to hold it separately. For high-density polyethylene tanks, wait until the welder reaches 325 °F (163 °C). For metal, heat the welder to at least 375 °F (191 °C).

Once you reach the bottom edge of the crack or leak, move back up around its opposite side. Coat the entire rim of the leak with filler from the rod.

Note any gaps that haven’t been filled in. Go back and melt more of the rod so they are level with the rest of the tank. Ideally, the repair will look even and consistent throughout. You may notice some uneven spots were you applied too much material by mistake, but these spots can be sanded flat later.

Avoid using the tank until the repair has solidified. If you try to use it too soon, you could end up weakening the repair.

You could also use tools like an angle grinder that make the process much quicker. However, be very careful to avoid touching areas that don’t need to be sanded.