How to repair a defective lawnmower drive

The lawn mower is considered to be the Germans' favorite garden tool. When the engine fails, however, good advice is often expensive. We explain how to repair the most common defects.

From the drive to the cause of the error

While a few decades ago the petrol lawnmower was the only power-operated mower to be used in the garden at home, the range of possible devices is much more diverse today:

• Lawn mower with Internal combustion engine
• electric lawn mower with cable connection
• electric lawn mower with battery

Depending on the version, the lawnmower drive will turn out differently and a possible defect has its own causes.

Petrol-powered lawn mowers

A lawnmower drive with an internal combustion engine, however, has a large proportion of mechanical components. If malfunctions occur here, they can usually be eliminated quite easily by yourself. But you can also independently identify and repair various problems on the engine itself. A visit to a specialist workshop is only worthwhile when it comes to defects that are difficult to identify or very demanding details.

The bowden cables

Gas and brakes on gasoline-powered mowers are controlled by so-called Bowden cables, i.e. thin steel cables. The joints, deflections and connecting elements are heavily stressed by the repetitive movement, as well as dirt and dust. At first they run more and more difficult and in the end they can fail completely. In all cases, the result is an incorrect transmission of your "commands" to the motor.

Remedy:

• Spray trains with penetrating oil and move them several times
• Remove loosened dirt with a cloth
• Relubricate again

If the cables are defective, replace them as follows:

• Measure existing trains before dismantling and note down their length
• Remove defective trains
• Grease the new cable and thread it correctly through all guide points
• Insert the cable in the clamps and fix it
• Check function and if necessary readjust

Tip: If in doubt, photograph the built-in cables before dismantling. Then you can orientate yourself on the pictures for the installation.

The fuel supply

Petrol engines often show malfunctions due to soiling as the operating time increases. This includes dust and dirt in the air filter as well as in the fuel system. Both of these can lead to a defect in the lawnmower drive due to a change in the fuel-air mixture.

Remedy:

• Remove and clean the air filter
• Knock out, blow out with compressed air or wash and dry in a mild soap solution
• Remove fuel lines and filters
• Flush with clean fuel
• Check for damage
• Reinstall
• Check the tank for dirt
• Possibly. Drain the tank contents and clean the tank

Tip: Do not forget components such as the fuel tap during your inspection. Here, too, dirt can accumulate and disrupt the flow of fuel.

The spark plug

In addition to the fuel itself, however, it must also be ignited in the combustion chamber so that the lawnmower drive can do its job as a whole. If the engine does not start but there is sufficient fuel and air, check the spark plug as follows:

• Pull off the spark plug connector
• Unscrew the spark plug with a suitable wrench
• Check the tip of the candle
• If blackened, clean with a fine wire brush
• Screw in the cleaned or new spark plug
• Plug in the plug and start the engine

Axles and wheel bearings

A lawnmower drive that acts on the axles in addition to the knife can of course also have damage in this area. Most of the time, these arise gradually due to the increasing wear and tear of the heavily stressed components. A bent axle can, however, be seen quickly when looking from below. Defective wheel bearings, on the other hand, gradually become noticeable in the form of sluggish wheels, unusual noises or a noticeable decrease in drive power. On the other hand, a torn drive belt suddenly leads to the complete loss of the drive.

Remedy:

• Turn off the lawn mower and lay it on its side
• Perform a visual inspection of the components
• Consult operating instructions
• For information on component changes, e.g. B. Change the drive belt, carry out the work steps according to the instructions
• Have axles and wheel bearings replaced by a specialist workshop due to their complexity and the special tools required

Damage to the engine

As soon as it goes beyond these easily recognizable defects, it becomes very difficult for the layperson to determine the exact cause and to repair it professionally. Therefore, first check all options within the scope of your possibilities and then - if you have not been able to eliminate the problem - then go to a specialist workshop. When it comes to the motor itself or the drive of the cutting knife, it is a matter of safety-relevant issues that can only be dealt with with the appropriate knowledge.

Electrically powered lawn mowers

If your device has an electric lawnmower drive instead, a defect is very difficult to repair. Of course, you can check and repair the mechanical components as already described. As soon as it comes to the motor and its power supply, the work must be done by a specialist. However, you can check a few things yourself before going to the workshop and at least identify possible errors in advance:

• Check the supply cable for breaks, cracks or kinks
• Check connections and other cables on the control unit or motor
• If present: Remove fuse and check for damage / burn-out
• In the event of damage, replace the fuse with a suitable component
• Observe the operating instructions

Attention: Many hobby craftsmen consider working on electrical installations to be a simple task. However, because of the risk of electrical voltages, do not do any activity that you are not absolutely sure of!

Lawn mower with battery

With the battery-powered lawn mower, possible defects are essentially in the same range as with "normal" electrical equipment. Only the battery itself is another possible cause of a defect. However, you cannot repair anything yourself here either. The battery is usually replaced in the event of damage.

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