How To Fix Plastic Gas Tank On Lawn Mower

Lawn & Garden

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Owning lawn maintenance tools and equipment is easier said than done!

Of course, I can’t deny that they make your life a lot easier, but that doesn’t mean you can breathe easy. And so that these machines can serve you better and longer, regular maintenance becomes essential.

I also don’t eliminate the possibility of accidental damages. For something like a lawn mower, which is meant for regular use, don’t get surprised if you see a couple of dents and cracks at the end of the day.

Hence, when I spotted a significant hole in the plastic gas tank of my newly bought lawn mower, the danger bells went off! Thankfully, my very considerate neighbor, who also happens to be a dealer of the equipment, offered to help.

As he came over on a Sunday morning to get the job done, I decided to document the process. And to my relief, it wasn't something very challenging. If you’ve been asking how to fix a plastic gas tank on a lawn mower, read on to find an effective solution.

So, let’s get going, shall we?

Steps to fix plastic tank

Step 1

Before getting into the thick of things, I’d like to state that the technique used in my case involved heat. Since heating and cooling of plastic are time-bound processes, you need to have everything in the near vicinity and work quickly. Although the requirements are pretty basic, organizing them beforehand saves valuable time.

The list includes:

  • Heat gun

  • Box knife to clean the damaged area

  • Broad metal painter spatula to flatten the parts

  • Matching plastic to cut out the patch

  • An optional screwdriver (flathead side) for precision

Step 2

Once you have the tools, the next step is to clean the gas tank. The reason? Any foreign object like dust or grease can interfere with the welding process. Remove the tank (if possible) or use a fuel pump to drain the tank completely. Keep in mind that even a little fuel, in contact with the heat, can lead to dangerous explosions.

Upon removal, scrub it clean with dish soap and water until you can no longer smell fuel. Next, use a few drops of solvent alcohol like acetone and give a thorough rub to ensure optimum cleanliness. Also, clean the patch material to ensure that the two stick together fully upon applying heat.

Step 3

Using the box knife, take your time to smoothen the damaged area as well as possible. Remove any plastic finger or rough spots or edges, as they may promote further splitting and cracking. Don’t be too harsh, but apply gentle force to make the area smooth.

Step 4

Now, take a close look at the area to get a near-perfect idea of the length of the required patch. Since my neighbor is a pro, he did not take much time to get the job done. However, if you’re a first-timer, it’s better to get hold of a measuring tape or scale.

Also, it’s a good practice to cut out a slightly bigger patch than needed. This will allow some margin for error, and you can always fuse the excess to the tank’s body.

Step 5

Start off by heating the damaged area with the heat gun. Make sure to hold it at a distance and apply the heat at a broader area, rather than on a concentrated spot to avoid burning or melting. When you notice that the plastic has become pliable and appears to be “wet,” move the patch material into the air stream of the heat gun. This will simultaneously mold the patch and the damaged area.

Upon observing similar wetness, drop the patch on the required area, and slowly move away the heat gun. With the spatula, softly go over the patch to remove any air bubbles. Here again, don’t apply too much pressure.

A small tip: practice the ‘drop’ beforehand to achieve perfect alignment. Once in place, you will not be able to remove the patch.

While the fused parts are still cooling, gently clean up the adjoining areas. The flathead of the screwdriver will come in handy for corners and specific spots. However, don’t rush into things by putting water or wet towels. As the plastic cools, the materials fuse to cover the damage.

In case the patch material is too thin, repeat the process twice or thrice until you reach the desired thickness. Besides, thinner patch materials make the repair more controllable. But do ensure that each layer cools down completely before you can apply more heat.

Since this forms a molecular bond between the two materials, the patch becomes permanent and doesn’t lose its ‘grip’ as quickly as in the case of glue or tape.

Step 6

Test the tank for any potential leaks by filling it with water. Furthermore, you can also pressurize it to check fatigue issues. If the process is successful, you’ll get a solid, possibly ever-lasting patch that doesn’t need frequent touch-ups.

Step 7

As an additional step, you may also use a coat or two of matching plastic compatible paint to hide the patch.

Summing It Up

If you ask me, the process wasn’t difficult per se, but was time-consuming. You need patience and minute attention to detail at every step to ensure a foolproof repair. So, in that sense, set aside considerable time to go about the job.

Before I sign off, I’ll leave you with some words of advice:

  • Never bring hot tools in contact with the plastic (both tank and patch).

  • Thoroughly clean everything before and after applying heat.

  • The patch material should be of the same quality/thickness as the tank.

  • Different plastics react differently to heat. So, test the entire process on spare plastic beforehand.

  • Apply enough heat to mold the plastic, but don’t melt it.

With this, it’s time for me to bring down the curtains. Hope this helps you get through the seemingly tough job. However, if you're looking to buy a worthy gas lawn mower, check out this list.

Until next time!

About the Author

Stacey is a Texan at heart and a true daughter of the soil. She takes keen interest in everything related to lawn care, and has experience of over 30 years in tinkering with a variety of equipment. When she's not tending to her own lawn or helping the neighbors, she likes to blog about her journey with the rest of the world.

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