Each year, the arrival of spring is heralded by the sound of lawns being mowed. If you want your lawn mower to last from year to year, treat its engine with the same respect you show your car's engine, says a machinery specialist in Penn State's College of Agricultural Sciences.
"A good lawn mower should last 8 to 10 years," says James Garthe, instructor in agricultural and biological engineering. "Too many people pay $300 for a mower, then get a new one a year or two later because it wasn't maintained properly."
It sounds trite, but Garthe says the best advice is to read the owner's manual and follow the directions for maintenance. Most manuals list what you need to know. Pay strict attention to the viscosity and quality of oil used in the engine.
"The wrong oil shortens your engine's life by causing overheating and excessive wear on valve guides, seals and main bearings," he says. "Use high quality engine oils, which contain additives that buffer corrosive acids generated during fuel combustion."
Keeping the air filter clean also extends your mower's life. "The air filter keeps dust, dirt, sand and grass from being drawn into the engine," Garthe says. "If the air filter is dirty, minute abrasive particles, especially silicon, can get into the internal moving parts, wearing and pitting them.
"A dirty air filter also keeps air from getting to the engine, affecting the air-fuel ratio that governs combustion," Garthe says. "The engine has to work harder, wasting energy and fouling the spark plug with deposits."
Check or change the engine's spark plug at either the beginning or the end of each mowing season. "Unscrew the plug and check the gap with a round (versus flat) spark plug gauge," Garthe says. "Carefully scrape deposits from the plug with a knife or wire brush. Take care, however, not to damage the porcelain insulator. If the porcelain is broken, the plug won't transfer heat away from the engine as it is designed to. If you find a broken spark plug, replace it with a new one of the same heat range."
Before storing the mower for winter, change the oil. "Late fall is the best time to change the oil and check the spark plug so that your mower will be ready to go next year," Garthe says. "Don't keep old oil in the engine until spring. Solids, water and acids that have accumulated in the oil over the summer will corrode your engine. Tie a tag on the mower to remind you when you serviced it, and what you did.
"Change the oil while it's still warm," he says. "Contaminants are suspended in warm oil and will drain out. If you wait until it cools, these materials settle to the bottom of the crankcase and solidify into a thick gum."
If possible before storing the mower, remove gasoline and accumulated dirt from the tank either by mowing until it stops or by wicking the last few drops with a rag. "Keeping old gasoline in the engine over winter can make it difficult to start next spring," Garthe says.
If you can't remove the gasoline, put a fuel stabilizer designed for small gas engines in the tank and run the mower for a few minutes before storing it. "A good fuel stabilizer can extend the storage life of the gasoline by up to six months."
If you keep your mower in a damp location, consider coating it with a water dispersant or rust inhibitor spray before storing it. "This creates a thin film that limits moisture penetration and discourages rust," Garthe says.
Covering the mower with a plastic tarp also can help to keep out moisture -- and rodents. "Mice routinely chew wires and other engine parts, and even build nests in the mower," Garthe says. A plastic tarp will discourage these pests better than cloth, which mice chew up for nesting material.
"These simple steps may keep you from having to buy a new mower next year," Garthe says.