Tip 2: How to Replace Trimmer Line Correctly

4 min read

Your trimmer line is finished, but how do you reload the head correctly? In OVDV Tip 2, Oli shows how to open the trimmer head, remove the old line, insert the new line and put everything back together correctly. Watch the video to see exactly how Oli explains and demonstrates each step.

When the cutting line on your grass trimmer becomes too short, breaks repeatedly or is completely used up, it is time to reload the trimmer head.

In OVDV Tip 2, Olivier shows how to open the trimmer head, remove the old line and install new trimmer line correctly.

The exact construction differs between brands and trimmer heads, but the basic principle is usually similar: open the head, check how the line is routed, insert the correct line and make sure everything can feed freely before you continue trimming.

When should you replace trimmer line?

Trimmer line is a wear part. During use it continuously comes into contact with grass, weeds, soil, fences, walls and other hard edges.

You may need to replace or reload the line when:

  • there is no line left in the trimmer head
  • the line has become too short to feed correctly
  • the line keeps breaking
  • the line is damaged, brittle or badly worn
  • the automatic or tap-feed system no longer provides enough line

Before assuming that the trimmer head itself is defective, check whether there is still enough correctly installed line inside it.

Step 1: Make the machine safe

Before touching the trimmer head, switch the machine off completely.

For a battery trimmer, remove the battery where possible. For a petrol machine, follow the manufacturer’s shutdown instructions and make sure the cutting head cannot start accidentally.

The head and line may also be hot immediately after use, so let the machine cool down before opening it.

Step 2: Open the trimmer head

In the video, Oli opens the trimmer head to access the spool and the remaining line.

Depending on the model, the cover may release using clips, tabs or a twist-lock mechanism. Do not force it. If you are unsure how your specific head opens, check the machine manual first.

Once the cover is removed, note how the spool, spring and line are positioned before taking everything apart. That makes correct reassembly much easier.

Step 3: Remove the old trimmer line

Remove the remaining pieces of used line and check the inside of the head.

Grass, dirt and small pieces of line can accumulate around the spool. Clean these out so that the spool can rotate and the line can feed without unnecessary resistance.

Also inspect the spool and eyelets for visible damage or heavy wear.

Step 4: Use the correct replacement line

Not every trimmer uses the same line diameter.

Using line that is too thick can prevent correct feeding and can put unnecessary load on the machine. Line that is too thin may wear very quickly or perform poorly.

Use the diameter and type recommended for your trimmer or trimmer head.

Step 5: Insert and wind the new line correctly

Oli demonstrates how the new line is fed into the trimmer head and positioned in the spool.

The most important points are:

  • follow the correct winding direction shown on the spool or head
  • keep the line reasonably even while winding
  • avoid crossing or tangling the line unnecessarily
  • leave enough line at the exits so the head can feed it correctly

Some modern trimmer heads use rapid-reload systems. Your own trimmer may use a different mechanism, so always follow the markings on the head and the instructions for your machine.

Step 6: Reassemble and check the head

Once the new line is installed, place the spool and cover back in their correct positions.

Before restarting the machine, check that:

  • the cover is fully locked
  • the line exits through the correct openings
  • the spool is seated correctly
  • no loose parts remain
  • the cutting head can move as intended

If the head does not close easily, do not force it. Reopen it and check the position of the spool, spring and line.

Why does trimmer line sometimes keep breaking?

Replacing the line solves the immediate problem, but frequent breakage can point to another issue.

Common causes include:

  • contact with walls, stones, fences or paving
  • incorrect line diameter
  • old or brittle line
  • line wound incorrectly inside the head
  • a damaged or worn trimmer head
  • too much line being exposed during use

If you repeatedly need to reload the head after only a short period of use, it is worth checking the complete cutting head rather than only replacing the line again.

OVDV Tip 2: take a moment before closing the head

The key lesson from Oli’s demonstration is simple: do not just push new line into the trimmer head and close it.

Check the winding direction, routing and seating of the spool first. Correct installation helps the line feed properly and saves frustration the next time you use the trimmer.

Need help with your grass trimmer or garden machine?

OVDV provides professional garden machinery maintenance and repair in Laarne and the surrounding area. If your trimmer head no longer feeds correctly, parts are worn or your machine needs maintenance, we can inspect it and advise you on the right solution.

Discover our Garden Machinery Service

Frequently Asked Questions

Maintenance Tip of the week Trimmer
Man operating a lawn mower in a grassy area with trees in the background

Portrait | Author

Olivier Vandevijver


I am the owner of OVDV in Laarne/Kalken and have more than 13 years of experience in the garden machinery sector. I advise, install and maintain robotic mowers from brands including Segway Navimow, STIHL and Honda — always based on the real situation of your garden: size, shape, slopes, obstacles and lawn edges. I also offer independent repair and maintenance of garden machines across different brands. And because a robotic mower can't do everything on its own, I also provide professional lawn edge care — so your garden stays not just automatically mowed, but clean and properly finished.
Learn more about him

Frequently asked questions

How do I replace trimmer line?

Switch the trimmer off and make it safe, open the trimmer head, remove the old line, clean the spool area, fit the correct replacement line in the indicated winding direction, route it through the exits and reassemble the head securely.
How do I know which trimmer line diameter I need?

Use the diameter and line type specified for your trimmer or trimmer head. Line that is too thick can feed poorly or overload the machine, while line that is too thin can wear quickly and cut less effectively.
Why does my trimmer line keep breaking?

Frequent breakage can be caused by contact with walls, stones or paving, incorrect line diameter, old or brittle line, poor winding inside the head, excessive exposed line or wear in the trimmer head.
Why is my trimmer head not feeding line?

Check that enough line remains, the spool is seated correctly, the line is wound in the correct direction, the exits are clear and the head is free of grass, dirt or broken line pieces.
Can I use thicker trimmer line in my grass trimmer?

Only use a thicker line if the manufacturer specifies that diameter for your machine or head. Oversized line can prevent proper feeding and may increase the load on the trimmer.