If the lawnmower no longer runs smoothly, jerks and shakes, you cannot avoid a repair. Instead of taking the money to a specialist workshop, you can sometimes repair your lawnmower yourself. You can find out how to do this here.
How to repair spark plugs on lawnmowers
If the engine of a petrol mower does not start after repeated attempts, it is very likely that it has ‘drowned’ in the carburetor and cylinder due to unburned fuel. In this case, experienced hobby gardeners first check whether the tank is empty.
If this shortcoming can be ruled out, proceed as follows:
- Move the throttle to the ‘stop’ position and pull it all the way through
- First, let the engine cool down and only then pull off the spark plug connector
- Remove the spark plug with the special spark plug wrench
- Dry and clean the spark plug or get a new one
- Never reuse candles with a cracked ceramic part
Screw the new spark plug into the thread by hand without using force as far as it will go. Then tighten 1/8 to 1/4 turn with a wrench to compress the spark plug seal ring. Finally, put on the spark plug cap. If you start the engine now, it should run smoothly.
Sharpen dull lawnmower blades yourself
If sharpening is not integrated into the maintenance program, frayed blades of grass when mowing signal a blunt lawnmower blade. You can either transport the mower to the specialist workshop or sharpen the mower blade yourself. Proceed with these steps:
- Thick work gloves, robust clothing, and protective goggles are mandatory
- Depending on the mower model, unplug the spark plug, unplug the power cord, or remove the battery
- Use a block of wood to stop the blade from turning and remove the blade bar
- Fix the lawnmower blade in a vise and sharpen it with a file
- Sharpen both sides evenly while maintaining the original cutting angle
- Completely remove the residual burr with a sharpening stone
Before the sharpened lawnmower blade is reinstalled, it should be checked for imbalance. To do this, hang it from the center hole on a nail or a screwdriver. If one side sinks, the balance is restored in another grinding pass.
Experts advise against grinding with a flex
In order to skilfully sharpen lawnmower blades, professionals also use workshop files. This tool gives you more control over the grinding process. Under a flex, the knife heats up so much that an uneven grinding pattern is created.
In addition, much more material is removed from the blade than is necessary. This shortens the life of the lawnmower blade and causes an undesirably large imbalance.
Repair clogged air filter yourself – instructions
If the engine performance is constantly reduced, the cause is usually a clogged air filter. The carburetor is no longer supplied with sufficient air, so the filter must either be cleaned or replaced. How to handle it correctly:
- Remove the air cleaner housing cover by removing the screw
- Remove, separate, and inspect the filter element
- Damaged filters must be replaced
- Dirty foam filters can be washed out with hot water and washing-up liquid
- Do not wet clean the paper filter, but knock it out or clean it with the suction nozzle of the vacuum cleaner
Place the air filter back in the housing and screw the cover tight. If the engine smokes when starting, there is still too much oil in the foam filter.
Adjust the carburetor – this is how you do it right
If a petrol (gas) lawnmower keeps stuttering, the carburetor setting is not correct. In older models, the fuel-air mixture for high speeds is set using a screw. This screw is often located near the throttle body. To reset the carburetor:
- Warm up the engine for about 5 minutes with the throttle half open
- Place the throttle in the ‘slow’ position
- Using a screwdriver, turn the fuel/air mixture adjusting screw so that the maximum speed is reached
- Then adjust the screw in the opposite direction until the engine runs at the desired speed
Check this setting by moving the throttle. If the engine does not accelerate smoothly now, the mixture screw must be adjusted again.
What to do if the electric lawn mower wears off?
While a performance problem with a petrol-powered lawnmower can be solved by replacing the spark plugs or adjusting the carburetor, the issue is more problematic with an electric lawnmower.
Here the motor is operated with a capacitor. If this is defective, the capacity decreases dramatically.
A defective capacitor cannot be repaired. New operating capacitors are available from specialist retailers. However, you should only replace the part yourself if you are an experienced do-it-yourselfer.
To be absolutely sure that you install the new condenser precisely, photograph the individual steps of the removal. When installing, simply proceed in reverse order.