How to Put a String on a Lawn Mower?

The satisfying hum of a string trimmer as it effortlessly tackles pesky weeds and overgrown grass is a soundtrack to many a summer afternoon. But what happens when your trusty string trimmer suddenly goes silent, leaving you staring at a tangled mess of cut string? Don’t despair! This comprehensive guide will walk you through the simple steps of replacing your lawn mower string, ensuring you can get back to tackling those unruly patches of green in no time. We’ll cover everything from choosing the right string to understanding the various types of trimmer heads and ultimately, equipping you with the confidence to tackle this common lawn maintenance task.

A Quick Overview

Replacing a string on a lawn mower is a relatively straightforward process that involves understanding your trimmer head’s type, selecting the appropriate string, and following a few simple steps. This article will guide you through each stage, providing valuable tips and tricks to make the process easy and efficient.

Identifying Your Trimmer Head Type

Before you start, you need to identify the type of trimmer head you have. There are two primary types: automatic feed heads and bump heads.

Automatic Feed Heads: These heads automatically dispense string as needed, requiring minimal user intervention.

Bump Heads: Bump heads, on the other hand, require you to tap the head on the ground to release more string.

Knowing your trimmer head type is essential, as the process for replacing the string varies between the two.

Automatic Feed Heads: A Step-by-Step Guide

Automatic feed heads are designed for effortless string replacement, but a few key steps will ensure a smooth operation. Here’s what you need to do:

1. Locate the String Access Point: Most automatic feed heads have a small, circular opening or a slot where you insert the new string.

2. Insert the New String: Carefully feed the string through the access point, ensuring it goes through the small opening or slot.

3. Wind the String: Most automatic feed heads have a winding mechanism, often a small knob, to wind the string. Follow the instructions provided by the manufacturer for winding the string onto the spool.

4. Secure the String: Once the string is wound, there is usually a mechanism, such as a spring-loaded bar, that secures the end of the string. Engage this mechanism to hold the string in place.

5. Trim Excess String: After winding the string, use scissors or a knife to trim any excess string, leaving about 1-2 inches protruding from the head.

6. Test the Head: With the string secured, give your trimmer a short run to ensure the string is feeding correctly and that the head functions properly.

Bump Heads: A Detailed Walkthrough

Replacing string in a bump head requires a little more manual manipulation, but the process is still quite simple:

1. Locate the Release Button: Most bump heads have a release button located on the side or the top.

2. Release the Old String: Press the release button to loosen the string and allow the spool to unwind. Pull out the old string from the spool.

3. Prepare the New String: If the new string is a single line, you may need to fold it in half. If it’s pre-spooled, you can skip this step.

4. Insert the New String: Feed the new string through the slot or opening on the bump head, ensuring it’s properly positioned on the spool.

5. Secure the String: Push down the release button and wind the string onto the spool by rotating the bump head in a clockwise direction. Continue winding until the desired length of string is on the spool.

6. Cut Excess String: Trim any excess string with scissors or a knife, leaving about 1-2 inches protruding from the head.

7. Test the Head: Test the head by bumping it on the ground to ensure the string is dispensing correctly.

Selecting the Right String for Your Trimmer

The type of string you choose will depend on the type of vegetation you’re tackling and the terrain you’re working with.

1. Nylon String: This is the most common type of string, offering a good balance of durability and cost.

2. Round String: Round string is ideal for general trimming and light-duty tasks.

3. Square String: Square string offers increased durability and is better suited for heavier cutting tasks and tougher vegetation.

4. Tri-Blade String: This type of string provides a more aggressive cut and can handle thicker weeds.

5. Monofilament String: This type of string is designed for high-speed cutting and is often used in professional-grade trimmers.

6. String Thickness: The thickness of the string will impact its performance and durability. Thicker strings will handle heavier vegetation, while thinner strings are better suited for lighter tasks.

7. String Length: Always choose a string length that is compatible with your trimmer head.

Tips and Tricks for String Replacement

  • Use Gloves: Wear gloves to protect your hands from any sharp edges or debris.

  • Keep It Clean: Always clean the trimmer head before replacing the string to prevent any dirt or debris from affecting the performance.

  • Follow Manufacturer Instructions: Refer to your trimmer’s owner’s manual for specific instructions on string replacement.

  • Invest in Quality String: Using high-quality string will ensure optimal performance and longevity.

  • Don’t Overtighten: Avoid overtightening the string spool as this can damage the trimmer head.

  • Store Your String Properly: Store your extra string in a cool, dry place to maintain its quality.

Troubleshooting Common String Trimmer Problems

While string replacement is a simple task, you may encounter some issues. Here are a few common problems and solutions:

  • String Not Feeding: Check the string feed mechanism for any blockages or debris.

  • String Breaking Frequently: Try using a thicker or more durable string.

  • String Not Cutting Properly: Ensure the string is correctly positioned on the spool and that the cutting head is not damaged.

  • String Tangling: Avoid using too much string, and make sure the head is properly installed.

Conclusion: A Job Well Done

Replacing a string on your lawn mower is a quick and easy task that will keep your trimming equipment in top shape. By following the steps outlined in this guide, you’ll be able to tackle any lawn maintenance job with confidence. Remember to choose the right string for your needs and to always follow the manufacturer’s instructions for optimal results. With a little effort, you can keep your lawn looking its best all season long.


Here are 7 FAQs and answers to help you understand the process of replacing the string on a lawn mower:

1. What type of string do I need for my lawn mower?

The type of string you need will depend on the model of your lawn mower. Some mowers use round string, while others use square string. You can find this information in your owner’s manual or on the sticker attached to your mower. It’s important to use the correct type of string, as the wrong type can damage your mower. You can typically find string at your local hardware store or online.

2. How do I know when I need to replace the string on my lawn mower?

You’ll know it’s time for a new string when it starts to break or fray, when the mower doesn’t cut the grass evenly, or when you hear a loud clicking noise coming from the mower. It’s a good idea to check your string regularly, even if it’s not showing signs of wear and tear.

3. How do I remove the old string from my lawn mower?

To remove the old string, you’ll need to open the trimmer head. This is usually done by pressing a button or lever on the side of the head. Once the head is open, you can simply pull out the old string. If it’s stuck, you may need to use a small screwdriver or pliers to help remove it.

4. How do I load the new string into my lawn mower?

The process of loading new string varies depending on the type of trimmer head. Some heads require you to wind the string around a spool, while others have a simple feed mechanism. Instructions on how to load your specific model can be found in your owner’s manual.

5. How much string should I use?

The amount of string you need will depend on the size of your trimmer head. It’s a good idea to fill the head to about 80% of its capacity. This will ensure that you have enough string to cut the grass evenly, but it won’t be so full that it jams the head.

6. How do I adjust the string on my lawn mower?

You can usually adjust the length of the string by turning a knob on the trimmer head. If your string is too long, it can get tangled or break. If it’s too short, it won’t be able to cut the grass evenly. Experiment with different lengths until you find one that works best for you.

7. How often do I need to replace the string on my lawn mower?

The frequency of string replacement depends on how often you use your lawn mower and the type of terrain you mow. If you mow frequently on thick grass or in rough terrain, you’ll need to replace the string more often. However, if you only use your lawn mower occasionally on a well-maintained lawn, you can likely go several months or even years before needing to replace the string.

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