How to Repair a Lawn Mower

It can be very demoralising to attempt to cut your grass and find that your lawn mower refuses to cooperate. It is common for these types of machines to experience issues after a few years of hard work; the key with lawn mowers is to spot the issues early, as this means you will be able to prolong the overall lifespan of your trusty machine.

One way to avoid any potential pitfalls is to regularly service your lawn mower; you should be looking to give your machine a full service at the end of each cutting season. If, however, your lawn mower does give up on you, here are our top tips to help you identify the problems and fix them:

Typical Issues With Lawn Mowers

1. Running issues

Your lawn mower failing can be a real nuisance, but it doesn’t always mean that you need to replace the whole machine straight away. Often, the problems can be solved with quick fixes enabling you to get back to cutting your grass. Once you have identified the problem, it is usually easy to fix.

If you find that your machine won’t run properly, before you delve deeply into investigating the individual components you should first check that it isn’t clogged with leaves or debris. It is always possible that there is a blockage that is preventing the machine from running properly, and if you try to start a machine that is blocked too often it can seriously damage the inner workings. Checking the cutting deck should therefore be the first port of call but make sure the power is well and truly off before you do so.

Electric or battery lawn mowers have fewer parts than their petrol counterparts, but you still need to know what potential issues you could come up against.

If you are having problems getting the machine going, you will need to check the condition of the cables that drive the electricity. Over an extended period of use these cables can become frayed and can lose their efficacy. In these instances, a replacement cable will be a much better option than a new machine altogether, but you will need to get a professional to install the new cable. If there isn’t anything wrong with the cable itself, it is worth looking at the fuses or the extension cables as some extension cables are not compatible with certain lawn mowers due to the limitations in the required number of amps it takes to run.

Petrol machines are susceptible to a lot more problems as there are significantly more components that make the whole machine run. If you are using the lawn mower for the first time after winter you should check to see if you have any old fuel in the tank, as fuel can go stale after a while which is less efficient and will struggle to ignite. At best case your machine won’t run but the worst-case scenario is you could damage your engine.

Petrol lawn mowers can also have problems caused by old spark plugs. After a long period of use, spark plugs can become soiled due to carbon build up which can cause them to struggle to ignite the fuel. You can clean your spark plugs but it is often better to replace them at the end of each cutting season.

If your machine still doesn’t start you should take a look at your air filter. Petrol machines require air to ignite the fuel so if your air filter is clogged this will hinder the airflow. After long periods of use, filters can get clogged as a result of a build up of carbon so you should look to replace this at the end of each year in order to keep your machine working at its optimal level for as long as possible. 

2. Why is there smoke billowing from my machine?

Smoke may look alarming but it doesn't always mean there is a serious problem – especially for mowers powered by petrol. Sometimes smoke can be ejected from the mower as a result of the internal combustion process that makes the lawn mower run and it doesn’t necessarily mean the machine is broken.

If your petrol machine has smoke pouring out from it, the colour of the smoke can be the biggest indicator of the problem. If the smoke is black this means your machine is “running rich”. This means, effectively, that your lawn mower is burning off too much fuel. There are a few causes of this, chief amongst which is that the carburetor isn’t getting enough air, caused by issues with the air filter. If replacing the air filter doesn’t fix the problem after a few minutes you will need to adjust the carburetor to increase the airflow.

If you have white smoke coming from your machine, this would indicate your engine oil reservoir has been overfilled. The engine is burning off the excess oil, which is causing the smoke. This can be fixed easily by making sure the oil is at the correct level. White fuel can also occur if any fuel gets into the engine itself so this can happen if you are mowing on a gradient. It is often completely harmless and is easily fixed. What you will need to consider, however, is that this is essentially caused by an oil leak so you will need to check with your manual or consult a professional to mitigate any problems.

3. Why is my lawn mower not cutting correctly

A lawn mower not cutting correctly is usually caused by problems with the lawn mower blades. To get the most efficient cut, the blades need to be sharp, however after a long lifespan they can become blunt. When this happens, the blades will tear the grass rather than producing a clean cut, which damages the grass. It is an easy fix – all you need to do is sharpen or replace your lawn mower blades.

If you opt for the sharpening route, you will need to make sure they are perfectly balanced when they are returned to the lawnmower. The lawn mower blades spin incredibly fast so you need to make sure everything is in perfect condition. If you over-sharpen your blades on one side the blades become unbalanced and unstable. This is not only bad for the lawn, as it will affect the quality of the cut, but it can also cause irreparable damage to the lawnmower itself.