The spark arrestor screen sits inside the muffler on a gas-powered leaf blower. These screens help prevent heated gases from escaping the internal combustion engines. In many countries, these screens are a mandatory requirement for not just all leaf blowers, but most internal combustion engines, such as cars, motorcycles, chainsaws and other lawn and garden equipment.
The main purpose of a spark arrestor screen is to prevent ignited gases from leaving the engine. In really dry periods of summer and fall, these heated gases, if they escaped, could start a fire, which, in many areas, can have disastrous, even fatal consequences for the local population. For this reason, the U.S. federal government prohibits the use of any outdoor gas power tool without these screens properly installed. These screens must meet the federal requirements as required by law.
Inhibits Engine Performance
While these screens severely reduce the risk of fires, they are also notorious for inhibiting engine performance. As the heated gases try to escape the cylinder, they are momentarily trapped by the screen. These gases will gradually build a layer of carbon deposits along the screen and muffler walls. When these deposits get too thick, they will prevent the heated gases from escaping the engine. This will reduce the amount the piston can move up and down and inhibit the amount of power.
Cleaning the Screen
The owner of the leaf blower is responsible for the cleaning and maintenance of the spark arrestor screen. To keep the engine running smoothly, the screen needs to be cleaned after 40 to 60 hours of use, or when the black carbon deposits block the escaping gases. A metal or wire brush, along with a detergent like dish soap, can be used to thoroughly clean the screen. Scrub out the muffler walls and along the exhaust port with the brush as well.
Replacing the Screen
If the screen has been damaged or can't be cleaned, it will need to be replaced. Remove the screen from the muffler and install another spark arrestor screen intended for your model of leaf blower. These screens must have a way to trap the carbon and meet all federal regulations. Make sure the spark arrestor screen is properly installed each time it's removed to prevent fires. While they aren't 100 percent effective, spark arrestor screens are extremely important.