How to repair a leaking lawnmower gas tank, step by step


Fuel dripping from your lawnmower gas tank is a hazardous issue that should be solved quickly. Fuel tank cracks are generally the result of long-time use or an accident. It can be the aftermath of the tank striking a low-hanging tree branch. Or debris falling on the lawnmower when it is parked or accidentally hit something.

Plastic built gas tanks are tough and irrepressible, but they can crack, split, break or spring a leak through accidents or misapplication. Polyethylene is a widely used material for lawnmower gas tanks. It is a material that is reasonably easy to repair at home.

How to repair a leaking lawnmower gas tank, step by step:

  • Step 1: Drain the tank
  • Step 2: Take out the gas tank
  • Step 3: Clean the gas tank and locate the problem
  • Step 4. Cut plastic pieces by knife or by Sand
  • Step 5. Take the dimensioning of the wrecked area
  • Step 6. Prepare for heating, i.e., heat the damaged area
  • Step 7. Place the patch material
  • Step 8.  Remove air bubbles
  • Step 9. Let the damaged area well-ventilated
  • Step 10. Attach the fuel lines to the fuel tank
  • Step 11. Refill the gas tank

This blog post will help you to fix your lawnmower’s leaking gas tank.

General systematic guide

Before starting the fixing process, you should gather the essential tools needed to repair the gas tank. These include a heating gun, knife, flat head screw, paper towel, hand gloves, and safety goggles. Additionally, a repair kit with epoxy resin and fiberglass, or for larger areas similar plastic as the tank.

Follow the steps mentioned below to fix the damaged or cracked plastic gas tank of your lawnmower.                                                                                     

Step 1. Drain the gas tank

Before you can start with the fix, you first have to drain the remaining gas from it. Use a suited gas container for it. Disconnect the fuel line attached to the carburetor, and let the remaining gas drain into the container. You can use this gas later again.

Step 2. Take out the gas tank

Use a screwdriver to unscrew the screws holding the tank to the lawnmower and remove it. Check again if it is empty, as it can still contain some leftover gas. Use the torch to check for debris and try to remove it.

Step 3. Clean the gas tank and locate the problem

Clean all the dirt from the gas tank by using an old rag. Then clean the gas tank using liquid soap and warm water. And finally, remove all the unwanted pieces of dirt that are still on it by rubbing the tank with alcohol. It is unnecessary to be spotless, but the cleaner it is, the easier it is to fix it. Now use a strong torchlight and shine inside the tank. This makes it much easier to spot cracks or small holes. Mark the locations with a marker.

Step 4. Cut plastic pieces by knife or by Sand

If the crack is bigger, there are two techniques to remove the loose plastic from a damaged area:

  1. Knife: Use the box knife to take out all kinds of loose strings of plastic from the wrecked area.
  2. Sanding: Sand the area that needs to be fixed with sandpaper. The location must be “roughed up” to permit a solid bond for the adhesive. The ridges from roughing up the plastic will enable the adhesive to be settled down and grab hold, making for a much resilient bond. Using a rag, you have to rub the area of all dust after sanding

If the leak is small it only needs to be sanded.

Step 5. Take the dimensioning of the wrecked area. 

Depending on how you will fix the leak, with some additional plastic or with the repair kit the following needs to be done:

  1. Repair kit: Using scissors, cut the encircled fiberglass repair patch to fit the area. Cut the patch to slightly overlapping the place that is to be fixed.
  2. Plastic method: Cut the plastic to the needed dimensions to completely cover the damaged area. Make the size 1.5 times larger, so there is a significant overlap outside of the damaged area.

Step 6. Prepare for heating and Heat the damaged area.

When the plastic patch material will be used and is cut to the correct dimension, it is time to heat things. First, start heating the damaged area with the aid of the heat gun. During this process, you need to care about two things. Firstly, heat the damaged area from some distance so that the plastic never burns or give smoke. Secondly, the goal is to make the plastic flexible without melting it or losing its shape.

Step 7. Place the patch material.

When you see the place is slowly becoming flexible and feeling a little wet, place the pre-prepared patch material on it. Coat the area to be repaired using the applicator stick after the patch is pertained, enveloping the patch with more adhesive while imbricating the edges. Enact the plastic epoxy adhesive to the tank over and around the spores. Extend the adhesive well and away farther out than the volume of the piece you have cut. Wrap the complete patch with more epoxy plastic adhesive, and do not go lightly. Confirm that the entire material patch is covered, and ensure that the bond is well applied past the patch’s ends. Continue heating until the patch element becomes wet as well. Remove the heat gun and place it in a safe place. When this is done correctly, there should be no sign of the patch viewing through.

Step 8. Remove air bubbles:

Take the spatula and then use some light pressure to the heated patch area to remove any air bubble from that area. Please do not use too much pressure, as it will ruin the shape of the tank. After all the air bubbles are removed, wait until the patch element has adhered well to the tank. 

When the patch is cool, check the tank. If you sense that the patch is thin, apply an additional patch again following the previous process. Put pressure on the material piece onto the adhesive that covers the hole. Please make sure it is pressed firmly into the adhesive and that all sides and corners are pressed into epoxy.

Step 9. Let the damaged area be well ventilated.

Permit the epoxy to dry. Check the manufacturer’s guidelines on how much time this should take. Some epoxy formulas cure within five minutes. Others will take half an hour or more.

Step 10. Attach the fuel lines to the fuel tank

Carefully reattach the fuel lines and adjust the component to the main assembly. Push the fuel line onto the tank fitting and secure it with the spring clamp. Make sure they are connected correctly, so no fuel leakage occurs.

Step 11. Refill the Gas Tank

Clean the repaired area with a paper towel. Fill the gas tank with gas and check the tank again for leaks. If all is ok and there are no leaks, the fix is done!

Additional Concerns:

Check the following concerns that are important to repair a leaking gas tank: 

  • Clean: Clean all materials and the gas tank before starting the fixing process.
  • Heat slowely: Heat the gas tank slowly; otherwise, it will burn or be damaged.
  • Suitable patch: Use suitable plastic built when repairing a plastic gas tank.
  • Test the plastic patch: Test the plastic piece before fixing it with the tank because every plastic has a different melting temperature. 
  • Hot plastic: Do not touch hot plastic with bare hands.
  • Empty the gas tank: Empty the gas tank before fixing it. Otherwise, it may explode when you heat the tank. 
  • If still leaking: If any leakage appears after fixing, vacate the gas tank completely and cleans it to fix it again. 
  • Epoxy: Many adhesives like epoxy plastic resin melt the plastic through a chemical reaction. It will make the patch as strong as the original plastic tank, and these patches will last the lifetime of your mower.

Frequently asked questions

1. How can I fix a hole in my gas tank?

At first, find the leakage or point of escape in the gas tank. Then, sand the Leaky Area of the tank and wipe the surface. Now, mix the epoxy and apply the epoxy. In the end, insert the epoxy in the hole and fill the tank with gas.

2. How to Repair a Black Plastic Lawn Mower Gas Tank?

Start with draining the tank of any residual gas. Then, Sand the area that needs to be fixed with the sandpaper that comes with the kit. Besides, by using the scissors, cut the enclosed fiberglass repair patch to fit the area. Now, Mix the two-part adhesive compound from the tubes in the repair kit.

3. How do you seal a plastic gas tank leak?

Firstly, Seal the Plastic Gas Tank with the help of Epoxy Glue. Next, Drain the gasoline from the tank and let it dry. Last but not least, Sand the area around the spores or cracks, and dirt-free the room with a shop cloth saturated with rubbing alcohol. Finally, blend the epoxy and put it all around the perimeter of the opening.

Final remarks

You always have to remember a golden rule that a machine takes care of you as long as it’s being taken care of. This article explains in detail how to fix a leaking plastic gas tank on a lawnmower. It is not a complicated task, but it takes some time. Another solution would be to replace the fuel tank, but that will be more costly.

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