Line trimmer and brushcutter maintenance

For long-term top performance, your trimmer needs regular maintenance. Find out what your trimmer requires to ensure that it will perform well for many years to come.

A STIHL FS 240 brushcutter in grass with a man preparing for maintenance in the background
Cleaning the mowing head during maintenance of the STIHL FS 131 brushcutter

What to consider when maintaining your brushcutter

When it comes to maintaining your brushcutter, reading the instruction manual carefully is the first step – the most important maintenance tasks are outlined there. Only perform maintenance tasks as advised and described in your instruction manual. For all other repairs and servicing visit your STIHL dealer, who has the expertise to safely restore your tool to working condition. 



It’s essential to use the right fuel for your petrol line trimmer or brushcutter - we recommend STIHL MotoMix. Not only is it perfectly formulated for the engine and ready- mixed, it also offers very low emissions, high performance, and is storable for long periods.  The STIHL filling system prevents fuel from spilling and also helps ensure you do not overfill the tank.


Line trimmers and brushcutters work with mowing heads that can be quickly and easily replaced as required. The condition of the cutting tool is important for smooth operation of your trimmer, so you should regularly check it as part of your maintenance routine. It is crucial to note that the various types of mowing heads have different requirements:

  1. For a mowing head with line (e.g. AutoCut, SuperCut): open the mowing head and check that the line is wound correctly – the lines should not cross over each other. If they are not correctly aligned, wind a new genuine STIHL mowing line onto the head.
  2. Mowing head with plastic blades (PolyCut): inspect the mowing head for cracks – these signs of wear let you know when the mowing head needs to be replaced. All three blades of the PolyCut must always be replaced as a complete set.
  3. Metal cutting tools (e.g. a grass-cutting blade or shredder blade) must be checked in case they need sharpening. If they are bent or broken, they must be replaced.
Cleaning brushcutter blade


Once you have completed your work, clean the trimmer guard and cutting tool with a damp cloth or a soft brush; for very stubborn dirt you can use an all-purpose cleaner. As you clean, check that the components are mounted securely and correctly.

Cleaning your line trimmer and brushcutter

Maintenance is a good opportunity to clean your trimmer thoroughly – find out how to clean your trimmer properly.

A person removing grass from a STIHL brushcutter with a soft cloth to clean it

Tools and materials

Below is a list of the most important tools and materials you need to clean your trimmer at a glance. When working, you should always wear personal protective equipment in accordance with the instruction manual.

  • Brush/paintbrush
  • Soft cloth
  • Multi-purpose cleaner
  • STIHL Varioclean
  • Combination socket tool
  • Work gloves
A person cleaning the guard of a STIHL brushcutter with a damp cloth

Cleaning the guard and housing

To ensure that you get the best out of your trimmer, you should make it a habit to clean the trimmer guard and housing immediately after working with the power tool – before any residues dry on. Before starting, pull out the plug on an electric trimmer, remove the battery on a cordless trimmer and switch off the engine on a petrol trimmer.

Use a damp cloth or a soft brush to clean the housing and the guard of your trimmer, or an all-purpose cleaner for stubborn dirt.

A person removing the air filter from a STIHL brushcutter to clean it

Cleaning the air filter

Air filters clean the carburettor air and become dirty over time. Therefore, you should remember to clean the air filter of your trimmer when necessary. Open the filter housing as per the operating instructions and remove the fleece or paper filter. Tap it out to clean the filter.

Please bear in mind that fleece filters are deep filters. This means tapping only loosens the dirt particles on the surface. Fine dirt particles are firmly seated within the material and can only be removed with special cleaners such as STIHL Varioclean. After cleaning with STIHL Varioclean, allow the filter to dry at room temperature.

Some devices have a coarse metal filter instead of a fleece filter. This is used to clean the engine cooling air. When cleaning your trimmer, simply tapping this out or rinsing it under running water is usually sufficient.

Cleaning the cylinder cooling fins

To ensure that your trimmer runs safely and can perform at its best, we recommend cleaning the cooling fins of the cylinder regularly. Clean with a brush or using compressed air.

Close-up of a spark plug on a STIHL petrol brushcutter

Cleaning the spark plug

Problems starting a petrol trimmer may indicate that the spark plug is dirty. A lint-free cloth is ideal for cleaning the spark plug. Please follow instruction manual for removal and testing.

It is worth replacing the spark plug if there are severe signs of wear or after a certain number of operating hours. 

Too much engine oil in the fuel or a dirty air filter is bad for the spark plug.

If the spark does not transfer

One possible source of malfunction is the spark plug. As a wear part, it must be replaced regularly. If a new spark plug doesn't help either, you should take your brushcutter to a STIHL dealer for inspection.

Caution: You should never clean the exhaust or carburettor of your trimmer yourself. You must visit a STIHL dealer to have the carburettor or the exhaust cleaned.

A man wearing STIHL protective equipment refuelling a STIHL brushcutter with a petrol-oil mixture


This may be because of the petrol mixture – you should not be using fuel that is over 30 days old. If you’re not sure how long the fuel has been in the tank of your grass trimmer, it’s best to replace it.

Overview: line trimmer and Brushcutter maintenance

  • For safety reasons, always read the instruction manual first.
  • Make sure you use the right petrol mixture in your trimmer.
  • Always check the cutting tool before you start work.
  • Always clean the trimmer after finishing work.
  • Replace the fuel mixture as required.

more Line trimmer and brushcutter tips