A petrol lawn mower is handy. With it you can effortlessly reach every piece of the lawn without having to drag an annoying cable behind you. Sometime in late autumn, the last round of mowing is due. After that, the lawn hardly grows and the lawnmower can take a break. He shouldn’t take any leftover petrol in the tank with him to his winter storage location. Why is that and how do we get it completely empty? This guide will show you how to properly drain the gas from a lawnmower.

Fuel is subject to change

Gasoline is a chemical mixture. It can react with substances that are in its immediate vicinity. For example with the oxygen in the tank. This changes it and with it its quality. From a chemical point of view, the following reactions take place – unnoticed by our eyes:

  • light hydrocarbons volatilize
  • other ingredients oxidize with oxygen
  • this causes them to clump together
  • so-called oxidation inhibitors cannot completely stop the process
  • the ethanol component absorbs moisture from the environment
  • above a certain degree of saturation, it sinks to the bottom of the tank
  • there it has a strong rust-promoting effect

The time factor also determines how the chemical processes affect the typical properties of the gasoline.

Note: The petrol tank should not only be empty over the winter. This also applies to every mowing break that lasts longer than four weeks. It doesn’t matter what time of year it is.

Adverse Effects

We will feel the effects of the chemical processes listed above in the spring of the following year at the latest. The grass has grown quite a bit, the first mowing of the year is due. But the lawn mower just won’t start . The gasoline has lost its ignitability. This cannot be restored with a fuel that has been modified in this way. The hastily refilled “fresh” petrol will not bring the hoped-for result. The newly formed mixture still does not have sufficient ignitability. After all, the “deficient” fuel is still in the lawnmower’s tank.

The formation of rust in the tank will also make itself felt at some point. Even if maybe not immediately in the following year.

Why drain the tank?

With an empty tank in winter, chemical reactions and thus starting difficulties in spring should be completely prevented. The free space in a tank that is not full is filled with air. In turn, the air contains oxygen, with which the fuel enters into a chemical reaction. As soon as oxygen is withdrawn from the air volume in the tank, this imbalance is compensated for by the ambient air. This keeps the chemical process running. There is enough time until spring to make the petrol unusable. A half-full tank is therefore not a good idea in the long run.

dangers of emptying

Improper and careless handling of petrol poses a number of health risks for people. These come from the rising petrol vapors. They can easily be inhaled into the lungs and cause damage there. All kinds of instructions for emptying the tank are circulating on the Internet, which almost conjure up these dangers.

In particular, stay away from tips if you have to suck the fuel with your mouth. The draining of petrol in buckets, bowls, etc. is not advisable. These can be knocked over far too easily. The liquid would seep into the ground, spreading its toxic fumes in the process. More suitable emptying methods are described in more detail below.

Instructions for the most convenient variant

Start the engine and let the petrol lawn mower run at idle until all the fuel has been used up. This method cannot exactly be called environmentally friendly. But compared to the exhaust fumes that come out of the exhaust pipes of cars every day, the amount is small. You can also help ensure that the idle time is short-lived. At the end of the mowing season, if necessary, only add a small amount of fuel.

Instructions for a suction pump

You can also drain the gasoline with a special oil drain pump. It sucks in the liquid fuel, and gravity takes over the flow. Such pumps are available in different versions. The cheapest copy costs around 10 euros. It can be used multiple times. Below are the instructions for draining petrol from a lawnmower using such a pump.

  1. Read the pump manufacturer’s instructions for use. Handling may vary from model to model. In addition to pumps that can be operated manually, there are also fully automatic models.
  2. Obtain a sufficiently large petrol can.
  3. First, clean the petrol lawn mower of grass and soil residue. This way the pump cannot get dirty. Follow the manufacturer’s instructions so that the lawn mower cannot start unexpectedly and possibly injure you.
  4. Push the lawnmower to a place that is convenient for dumping.
  5. Elevate the lawn mower. The petrol tank should be higher than the petrol can, otherwise the fuel will not flow out. How you bring about this increase is the same. However, it should be strong enough to support the weight of the lawnmower.
  6. Open the cap of the petrol tank and the petrol can.
  7. Insert one end of the hose deep enough into the tank. The other end into the opened petrol can. Attention: This must not happen randomly. Make sure beforehand which end of the hose goes where.
  8. Start the suction mechanism.
  9. Wait for the fuel to drain from the petrol lawn mower.
  10. First, pull the hose out of the lawnmower. Hold it up so that it is completely emptied into the petrol can.
  11. Close the petrol tank and the petrol can tightly.

Filling up instead of emptying?

Draining the petrol from a lawnmower is intended to prevent its chemical change. With the goal that the petrol lawnmower starts again in the spring without any problems. Just like emptying the tank, filling it up should also be able to do this. When the entire volume of the tank is filled with petrol, there is no more room for oxygen. This means that oxidation processes are not possible. That sounds plausible so far. For this reason, this method is also recommended by some manufacturers. In addition, a commercially available fuel stabilizer should be used.

Check what your lawn mower manufacturer recommends in the owner’s manual or on their website. There’s no harm in sticking to it.

Tip: A fuel stabilizer that is added later cannot reactivate the original properties of the gasoline. It must therefore be attached before storage.

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