Maintain your lawnmower

Preventative maintenance

Preventative lawnmower maintenance is carried out to circumvent larger, costly repairs. Included in the owner’s manual is the manufacturer’s recommended service schedule. It will stipulate how often routine maintenance tasks and checks should be performed. Foremost is cleaning grass from the lawnmower housing and undercarriage after each use. Petrol lawnmowers require more dedicated maintenance than electric models. The four major serviceable components on these are blades, oil, air filter and spark plug replacement.

 

Engine types and oil

There are two types of petrol lawnmower engines. Two-stroke engines use a mixture of oil and petrol mixed according to the manufacturer’s predetermined ratio (a general guideline is around 20 parts of petrol to one part two-stroke oil, or 10l petrol to 500ml oil). Some lawnmowers come with a separate tank for two-stroke oil and another for fuel, while others have only one tank and fuel must be premixed manually.

In the case of older lawnmowers with two tanks, it is preferable to premix fuel because the capillaries within the regulating system may become clogged over time, altering the oil/fuel ratio. Adding too little oil to the fuel will destroy the engine as the cylinders do not get the lubrication required. On the other hand, too much oil will make the mower perform poorly and will cause carbon build-up on the spark plug and cylinders. Social business developer from L&G Tools, Deeren Naik says, “It is important to use a fresh tank of fuel/oil mix when starting the lawnmower after a period of non use.” 

 

Four-stroke engines are more environmentally friendly and do not require special mixing formulas. Instead, oil is contained in the crankcase. This oil should be changed once a year before the growing season begins. “If crankcase oil isn’t changed on a regular basis, dirt and contaminants will build up and this will result in premature wear and tear or failure,” says Deeren.

 

Before removing the oil drain plug on a four-stroke lawnmower, run the engine for a few minutes to warm it up. This will allow the oil to drain faster, removing more contaminants in the process. Old oil should be collected in an oil pan and disposed of in a responsible manner. Using the grade of oil recommended by the manufacturer, fill the crankcase until the oil is visible through the oil fill hole or until it has reached full on the dipstick.

 

Air filter

The air filter is designed to trap dust and debris to protect the engine. The two most commonly found types of filters are made of either paper or foam. Paper filters can be cleaned by dusting off the surfaces. These filters are disposable and water or air filter cleaner sprays cannot be used. Foam type filters on the other hand can be removed, washed in soapy water and refitted. If filters cannot be reconditioned, replacement filters can be purchased from your supplier.

 

Spark plugs

The spark plug provides the spark for the combustion cycle in the engine. If the gap on the spark plug electrode has widened, worn out or become fouled, it will be difficult to start the mower and it will not run smoothly. Sometimes it is possible to recondition the plug with a wire brush, a set of feeler gauges and some carb cleaner. To remove the spark plug, start by removing the spark cable by pulling on the rubber end cap surrounding the plug. Once the cable has been removed, use a spark plug wrench or ratchet with a deep socket to unscrew the plug.

 

When replacing the spark plug, turn it in by hand until the threads catch to avoid stripping the threads. With the plug in place use a wrench to nip it tight. Spark plugs are not meant to be driven in too tightly and over-tightening can break the ceramic on the spark plug, strip the threads or damage the engine.

 

Troubleshooting

Fuel, air and spark are the basic ingredients needed for any fuel-powered engine to run. If just one of these is lacking, the engine will not run, and by checking these systems first, a lot of time can be saved. Start with the easiest solution and work your way on from there.

 

Begin by checking if the fuel tank has enough fuel and top up if necessary. If there is fuel, check to see that the fuel tap is open and that the choke is in the correct position. Old or contaminated fuel can also cause issues and it may be necessary to mix a new batch of two-stroke oil and petrol or to empty and refill a four-stroke mower with fresh petrol.  If this fails, there may be a fuel blockage; remove the fuel line from the carburettor and if the fuel is not coming through, try blowing into the fill hole or change the fuel filter.

 

If the fuel is running through smoothly, it is time to move to spark. Remove the spark plug and assess its condition. If all looks well, get someone to hold the spark plug, with lead attached, against the engine and give the pull start a tug. You should see a spark ignite between the engine and the spark plug. If there is no spark, there could be a problem with the plug or the ignition system. For safety reasons, the person holding the plug should wear garden gloves for protection because ignition systems work with high voltage.

 

Finally, check the air filter for blockages and try starting the mower with the air filter off. If all of the above troubleshooting has not provided an answer, you may have to look into the mechanical workings of the mower. This involves removing the carburettor for servicing or stripping
the engine to identify possible mechanical failure.

 

Lawnmower care tips

•  Check the condition and level of the oil after eight hours of use. As oil ages, it becomes contaminated with fuel and small pieces of the engine that have worn away. Replace oil once a year or after approximately 50 hours of use.

 

•  Add fuel stabiliser to fresh fuel to keep fuel fresher for longer. If the lawnmower is not going to be used for some time, rather drain the fuel as it can corrode and gunk up the carburettor. If your lawnmower has a fuel tap, turn it off after use and leave the mower running until it has used all the fuel in the line.

 

•   Blades should be sharpened every season and replaced every one to three years, depending on usage. Only use the blade recommended by the manufacturer.

 

Cutting tips

•  The lawn should be mowed regularly at a proper height. Your lawn may require mowing at least once a week during peak growth periods and can be mowed every second week during periods of slow growth.

 

• Refrain from cutting wet grass as it will not cut easily and can clog the mower or leave clumps of grass around the yard.

 

• Avoid scalping your grass too low. This forces the plant to tap into its food reserves and, over time, thin out. It then becomes susceptible to heat, cold, drought, pest attacks and disease.

 

Sources:         

www.repairclinic.com;          
www.briggsandstratton.com