Most people never look at the cooling fins. They're hidden under a plastic shroud on most edgers, with a flywheel fan that pulls air over them. The fan blows air down between the fins, the fins shed heat from the engine, and everything stays at safe operating temperature.

Problem is, the same fan that cools the engine also pulls in grass clippings, dust, and dirt. Over a few years, this builds up into a felt-like layer in between every fin. The layer insulates the engine instead of letting it cool. Engine temperature climbs, two-stroke oil breaks down faster, piston rings stick, and eventually the engine seizes.

Signs your cooling fins are choked:

• Engine getting hard to start when warm.
• Engine cutting out after 10 to 15 minutes of work, then restarting after it cools down.
• Smell of burning oil or hot plastic during use.
• Visible dust and grass packed around the cylinder when you take the cover off.

To clean them, take the plastic engine cover off (usually 3 or 4 screws). You'll see the cylinder fins underneath. Use a stiff brush or a piece of stiff plastic to scrape between the fins. Compressed air helps clean out what the brush misses. Be careful around the spark plug and the high-tension wire.

Don't use a metal screwdriver or wire brush, you can damage the fins. And don't use a high-pressure water blaster, water in the wrong places causes more problems than it solves.

Do this every couple of years on a regularly-used edger, every year on a tradie unit. Engine will run cooler, last longer, and be easier to start. One of those jobs that's invisible until you don't do it.