How to repair your lawnmower

Over an extended period of use, lawn mowers will develop issues. This can be delayed with regular maintenance and proper storage, but in some instances a lawnmower will need to be repaired. Fixing your lawnmower doesn’t have to be a daunting prospect; in fact, a lot of the biggest problems that occur with a lawnmower are easily fixable with a quick diagnosis.

With any repairs you should always consult your instructors manual before you undertake any work. This should always be your first step, as it will provide bespoke instructions on your machine. Once you have perused that, here are our handy quick tips to get you going again quickly.

Common lawnmower problems

1. Why won’t it start?

A lawnmower failing to start can be a massive pain, however, often it doesn’t always mean there are fatal problems. There are a number of causes that are simple to fix, and being able to understand and diagnose these problems early will help prolong the life of your lawnmower. Often, these issues will vary depending on the type of power used.

Before you look into the smaller components in more detail, you will need to check that there are no leaves or debris that are clogging up the works. If there is a blockage that is preventing the blades from turning this can seriously damage the machine.

Petrol mowers have a lot of smaller components that all work to make the machine run. If any of these fail, this can cause problems with your lawnmower.

If your lawnmower doesn’t start, there are a few things you can check. If petrol has been left in the tank for a while, this can cause problems with the machine but is easy to fix. Old fuel goes stale after a while which, at best, prevents it from igniting and, at worst, can damage your engine. You should also check the air filter on a petrol lawnmower. As the internal combustion engine needs air to ignite the fuel, a blocked air filter will prevent this from happening. After repeated use, air filters can get clogged up with carbon build up so you should look to replace this every year to make sure you get the best from it.

With electric or battery mowers, there are fewer parts but that doesn’t mean it cannot have problems. If your machine fails to start, you will need to check the health of the cables or batteries. The cable can become frayed after long periods of use, which can cause issues with the machines. In addition to this, some extension cables will not be compatible with the required amount of amps to run an electric mower. Another possible cause can be as a result of blown fuses.

2. Why is my lawnmower cutting out or slowing down during cutting?

This can be really annoying, especially if you are midway through cutting your grass as it can leave a half-cut lawn. There are, however, some simple fixes that can get you back up and running in no time. As with other problems, a quick diagnosis is imperative before major damage is caused.

The simplest reason for a lawnmower slowing down is due to the grass you are cutting. If the grass is too long for the cutting height, this puts an unwanted strain on the engine or motor, which causes the issues. Ideally, you shouldn't be cutting more than a third off the grass at any one time so you should always cut at a higher height first before dropping it down to the desired height.

You should also check to make sure there is no debris on the underside of the lawnmower that is clogging the blades. When you do check this, however, you will need to make sure that it is safe to do so and the power is not connected. The last thing you want is to unclog the blades for them to suddenly start spinning, as this can be very dangerous.

In a similar manner to when a mower fails to start due to issues with the power, the same issues can cause the mower to cut out midway through cutting the grass. Petrol mowers can experience issues caused by clogged air filters or misfiring spark plugs, which can be easily fixed. If you are unable to clean these components, a simple replacement will sort the problem.

With electric or battery mowers, the same issues that can cause a non-starter can also cause the mower to cut out mid-mow. You will then need to check the cables, fuses and connectors to make sure it is still able to get the electricity required to power the lawnmower. For battery lawnmowers you will need to check the health of the battery and make sure it doesn’t discharge too quickly. If it has trouble holding its charge for a decent enough time, you may need to replace the battery. Be sure not to store batteries in a cold place when they are not in use as this can affect the battery life.

3. Why is smoke coming from my lawnmower?

Smoke from the lawnmower can be alarming but it isn’t always an indicator that there is a critical problem with the machine. This is especially true for petrol mowers as sometimes smoke is ejected as a result of the combustion process that powers the machine.

In these cases the colour of the smoke can often be an indicator of the issue. If you are experiencing black smoke from your petrol mower this can mean it is “running rich”. What this means, in simple terms, is the machine is burning off too much fuel. Often the carburetor not getting enough air causes this. The main cause of this can be problems with the air filter as it is preventing air from getting into the carburetor so you should look to replace the filter and see if this fixes the problem. If this hasn’t sorted the problem after a few minutes you may be required to increase the airflow by adjusting the carburetor.

If you are have white smoke billowing from your machine this can be caused by an overfilled engine oil reservoir. The engine will burn off the excess fuel, causing the smoke. It is a simple fix, as you will just need to make sure your oil is at the correct level to prevent this from happening. White smoke can also occur if any fuel gets into the engine itself. If, therefore, you mow on a gradient or you have recently changed the oil this will not be uncommon. If this happens it is completely harmless and can be solved quickly by burning the excess oil off when you restart your lawnmower. As this, in essence, is caused by an oil leak you should consult your manual for advice on how to avoid and reduce issues of this nature.

4. Why is my lawnmower struggling to cut properly

The most common cause of this is due to issues with the blades themselves. If they have become dull due to a long lifespan this can cause an inefficient cut. When the blades aren’t sharp this means they tear the grass, as opposed to a clean cut, which damages the grass. To fix this, you will need to either sharpen or replace your lawnmower blades.

When you do service your lawnmower blades, you need to make sure they are perfectly balanced. Over-sharpening on one side can make the blade unstable, which can not only affect the quality of your cut but can also damage the lawnmower itself. The blade can spin at over a thousand times a minute so you need it to be correct.

If you are still unsure about any of these causes and how to fix them, the best place to go would be a registered service agent. McCulloch has a large number of places where you can take your machine across the country that can diagnose and fix issues quickly.

B40 P ELITE
B40 P Elite
MSRP:
-
Cylinder displacement 40 cm³
Cutting width 52 cm
OEM Grass blade Grass 255-4
CS 450 ELITE
CS 450 Elite
MSRP:
-
Cylinder displacement 45.7 cm³
Bar length (inch) 18"
Weight (excl. cutting equipment) 5.3 kg