How to Replace String in Weed Eater? Quick Tutorial for Homeowners

Introduction

A weed eater is one of the most versatile and essential tools for any homeowner looking to keep their yard neat and tidy. From edging sidewalks and driveways to cutting tall grass and overgrown weeds, it tackles jobs that a lawn mower just can’t handle. But like any tool, it requires regular maintenance to keep running smoothly – and the most common maintenance task is replacing the cutting string when it wears out or breaks. If you’ve ever stared at your broken weed eater and wondered how to replace string in weed eater, you’re in luck: this guide will walk you through every step of the process, no professional help required. Replacing the string is a simple, low-cost DIY task that takes less than 10 minutes once you know what you’re doing, and it will save you hundreds of dollars in repair shop fees or replacement tool costs over the life of your weed eater. We’ll cover everything from choosing the right string type for your yard to step-by-step instructions for both bump feed and fixed line models, plus tips to make your new string last as long as possible.

• Why Does Weed Eater String Break or Wear Out?
• What Tools and Materials Do You Need to Replace Weed Eater String?
• Types of Weed Eater String: Which One Should You Use?
• Step-by-Step Guide: How to Replace String in Weed Eater (Bump Feed Models)
• Step-by-Step Guide: How to Replace String in Weed Eater (Fixed Line Models)
• Troubleshooting Common Issues After String Replacement
• Tips and Best Practices for Extending Weed Eater String Life
• Frequently Asked Questions About Replacing Weed Eater String
• Conclusion

Why Does Weed Eater String Break or Wear Out?

Before you learn how to replace string in weed eater, it’s helpful to understand why the string wears out in the first place. This will help you avoid common mistakes that cause premature wear and save you time on replacements down the line. Weed eater string is made of durable nylon, but it’s not indestructible – constant friction, impact, and improper use will wear it down over time.

Common Causes of Premature String Wear

The most common reasons your weed eater string breaks or wears out faster than expected include:

• Impact with hard surfaces: Hitting rocks, concrete, fence posts, tree trunks, or curbs will quickly wear down the sharp edges of the string, and can cause it to snap on impact.
• Cutting thick, dense vegetation: Thick weeds, overgrown grass, and woody brush put extra strain on the string, wearing it down faster than light trimming around flower beds.
• Using the wrong string type: If you use a thin round string for heavy brush cutting, it will break constantly. Conversely, using a thick serrated string for light grass trimming will wear it down unnecessarily fast.
• Improper winding: Winding the string too tight or overlapping layers creates excess friction between the string coils, which causes it to break more easily and prevents the feed mechanism from working correctly.
• Built-up debris in the spool cavity: Grass, dirt, and small twigs that get trapped in the spool cavity can fray the string as it feeds through, leading to premature breakage.
• Improper storage: Storing your weed eater in direct sunlight or extreme temperatures can make the nylon string brittle, causing it to break more easily during use.

By addressing these common issues, you can extend the life of your new string significantly, reducing how often you need to replace it.

What Tools and Materials Do You Need to Replace Weed Eater String?

One of the best parts of learning how to replace string in weed eater is that you don’t need any fancy, expensive tools to get the job done. Most of the items you’ll need are probably already lying around your garage or toolbox. Below is a breakdown of essential and optional tools to make the process as smooth as possible.

Essential Tools for Every Replacement Job

These are the non-negotiable items you’ll need for every string replacement, regardless of your weed eater model:

• Replacement weed eater string: Make sure to get the correct type, thickness, and length for your specific model. You can find this information in your user manual or on the label of your old spool.
• Work gloves: The ends of new weed eater string are extremely sharp and can cause deep cuts if you handle them without protection. Gloves also protect your hands from sharp plastic burrs on the spool housing and any debris in the spool cavity.
• Safety glasses: When you remove the spool, small pieces of old string, grass, and debris can fly out, so safety glasses will protect your eyes from injury.
• Screwdriver (flathead or Phillips): Most weed eater spool housings are secured with a small screw, though some models twist off without tools. Check your model to see which type you need.
• Small brush (old toothbrush works great): You’ll use this to clean out grass, dirt, and debris from the spool cavity before installing the new string, which prevents jams and premature wear.

Optional Tools That Make the Job Faster

These tools aren’t required, but they can make the string replacement process faster and easier, especially if you have multiple weed eaters or replace the string frequently:

• Line trimmer spool winder: This cheap, handheld tool clamps onto your spool and winds the string evenly and tightly without you having to do it by hand. It’s especially helpful if you have large hands or struggle to wind the string neatly.
• Wire cutters: Standard scissors can fray the ends of nylon string, leading to breakage during use. Wire cutters give you a clean, straight cut that won’t fray.
• Silicone lubricant: A small spray of silicone lubricant on the spool shaft will help it spin smoothly, making string feed more consistently and reducing wear on the feed mechanism.

Types of Weed Eater String: Which One Should You Use?

Not all weed eater string is created equal, and choosing the right type for your yard and weed eater model is key to getting good performance and making your string last as long as possible. The two main factors to consider are the shape of the string and its thickness (diameter).

Round vs. Square vs. Star-Shaped String: A Comparison

The shape of the string determines how well it cuts through different types of vegetation, how durable it is, and how much noise it makes. Below is a comparison of the most common string shapes to help you choose the right one for your needs:

For most homeowners, square or star-shaped string is the best all-around choice, as it balances cutting power and durability for mixed grass, weeds, and occasional impact with small debris.

How to Choose the Right String Thickness for Your Weed Eater

String thickness is measured in inches or millimeters, and using the correct diameter is critical for your weed eater’s performance. A line that’s too thin will break constantly and won’t cut effectively, while a line that’s too thick will put excessive strain on the motor, causing it to overheat or burn out.

The correct thickness for your model is almost always listed in your user manual, and is often printed on the label of your old spool. For most residential electric and gas weed eaters, 0.065” (1.65mm) is the standard size for light to medium use. For heavier residential use (thick weeds, overgrown lots), 0.080” (2.0mm) is a better choice. Commercial models typically use 0.095” (2.4mm) or thicker line. If you can’t find the manual, start with 0.065” line, as it works for 90% of residential use cases.

Step-by-Step Guide: How to Replace String in Weed Eater (Bump Feed Models)

Bump feed is the most common string feed system for residential weed eaters. It works by releasing a small amount of string each time you bump the bottom of the head against the ground while the tool is running. If you’re tackling a bump feed model, this step-by-step breakdown of how to replace string in weed eater with a bump feed system will have you back to trimming in no time.

Safety First: Always disconnect the power source before working on your weed eater to avoid accidental startup, which can cause serious injury.

Step 1: Disconnect the Power Source

This is the most important safety step, and it only takes a few seconds. For gas-powered weed eaters, turn off the engine, let it cool completely if you just used it, then pull the spark plug boot off the spark plug to prevent the engine from starting accidentally. For corded electric models, unplug the power cord from the wall outlet. For battery-powered models, slide the battery pack out of the tool’s battery slot. Once the power is disconnected, you can work safely without risk of the weed eater turning on unexpectedly.

Step 2: Remove the Spool Housing

The spool housing is the plastic cover that holds the string spool in place, located at the bottom of the weed eater head. Most models twist counterclockwise to remove, though some have small plastic release tabs on the sides that you press in while twisting. If the housing is stuck, don’t force it – wiggle it gently while twisting to avoid breaking the plastic tabs. Once the housing is loose, pull it straight off the head to expose the spool inside.

Step 3: Remove the Old Spool and Remaining String

Pull the old spool out of the housing. Remove any remaining pieces of old string from the spool and the spool cavity. Use your small brush to clean out all grass, dirt, and debris from the cavity and the string feed eyelet (the small hole that the string feeds through). Built-up debris is one of the most common causes of string jams and premature wear, so take an extra minute to clean this area thoroughly.

Step 4: Measure and Cut the New Replacement String

Check your spool for the recommended string length – most bump feed spools hold between 10 and 15 feet of line. If there’s no marking, measure a piece of string that’s twice the diameter of the spool plus 6 inches for the free end that will feed through the eyelet. Cut the string with wire cutters for a clean, fray-free edge. Frayed ends will catch on the spool and cause jams, so a clean cut is important.

Step 5: Wind the New String Onto the Spool

Look for a small arrow printed on the spool – this shows the correct direction to wind the string. Winding it backwards will cause the string to feed incorrectly or not at all. Thread one end of the string through the eyelet in the center of the spool, then wind the string evenly around the spool, overlapping each layer slightly but not too tight. Leave 6-8 inches of free string sticking out of the eyelet, and tuck that end into the small notch on the side of the spool to keep it from unwinding while you reassemble the tool.

Step 6: Reassemble the Weed Eater

Place the spool back into the housing, making sure the free end of the string is aligned with the feed eyelet on the housing. Twist the housing clockwise until it clicks or is tight against the weed eater head. Reconnect the power source (spark plug, battery, or power cord), then test the feed by bumping the head firmly against the ground while the weed eater is running at full throttle. You should see 2-3 inches of string extend out of the head. If it doesn’t feed, double-check that the spool is seated correctly and the winding direction matches the arrow on the spool.

Step-by-Step Guide: How to Replace String in Weed Eater (Fixed Line Models)

Fixed line (also called “fixed head”) weed eaters don’t use a rotating spool to hold string. Instead, they use a pre-cut piece of line that you feed directly through the head and wind around an internal drum. The process for replacing string on these models is a little different from bump feed, but still just as simple. Here’s how to do it:

Step 1: Disconnect the Power Source

Just like with bump feed models, start by disconnecting the power to avoid accidental startup. Turn off gas engines and disconnect the spark plug, unplug corded electric models, or remove the battery from battery-powered models.

Step 2: Remove the Spool Cap

The spool cap is the small plastic cover on the bottom of the weed eater head. Most twist off counterclockwise, though some models have a small release lever that you press to remove the cap. If it’s stuck, wiggle it gently while twisting to avoid breaking the plastic.

Step 3: Remove the Old Line and Clean the Cavity

Pull out any remaining pieces of old line from the head. Use your small brush to clean out any grass, dirt, or debris from the internal drum and feed eyelet, just like you would with a bump feed model.

Step 4: Cut and Install the New Line

Check your user manual for the recommended line length for your model – most residential fixed line heads use 10-15 foot pieces of 0.065” or 0.080” line. Cut the line to length with wire cutters, then feed one end through the small eyelet on the side of the head. Pull the line through until both ends are sticking out about 2-3 inches from the eyelet. Hold the two ends together and wind them around the internal drum 2-3 full turns, being careful not to overtighten the line. Overtightening will prevent the line from feeding correctly during use.

Step 5: Reassemble and Test

Place the spool cap back on the head and twist it clockwise until it’s tight. Make sure the two ends of the line are sticking out of the small holes in the cap. Turn on the weed eater and bump the head against the ground to test the feed – the line should extend out evenly with each bump. If it doesn’t feed, make sure you didn’t wind the line too tight, and that the cap is seated correctly.

Troubleshooting Common Issues After String Replacement

Even if you follow all the steps correctly, you may run into a few common issues after replacing your weed eater string. Below are the most frequent problems and their easy fixes:

String Won’t Feed

If the string doesn’t extend when you bump the head, first check that you wound the string in the correct direction (follow the arrow on the spool for bump feed models). Make sure the free end of the string is tucked into the notch on the spool, and that the spool is seated fully in the housing. For fixed line models, make sure you didn’t wind the line too tight around the drum, and that the cap is tightened all the way.

String Breaks Immediately After Replacement

If the string snaps as soon as you start cutting, first confirm you’re using the correct string thickness for your model. Next, check the spool eyelet for sharp edges or burrs that could be fraying the string – sand it smooth with fine-grit sandpaper if needed. Finally, make sure you didn’t wind the string too tight, as this creates excess friction that causes breakage.

String Flies Out of the Head While Operating

If the entire spool of string comes loose or the line feeds out uncontrollably, the spool housing is probably not tightened all the way. Twist the housing clockwise until it’s fully secured, and make sure the spool is seated correctly inside the housing. For fixed line models, make sure the cap is tightened fully so the line doesn’t come loose.

Weed Eater Stalls or Loses Power After Replacement

If your weed eater struggles to run or stalls after you replace the string, you may be using string that’s too thick, which puts extra strain on the motor. Switch to the recommended thickness for your model. For gas-powered models, also check that the air filter isn’t clogged with grass and debris, as a dirty air filter can reduce engine power.

Tips and Best Practices for Extending Weed Eater String Life

Once you’ve mastered how to replace string in weed eater, you can take a few simple steps to make your new string last as long as possible, reducing how often you need to do this task. Follow these best practices to get the most out of your string and your weed eater:

• Always use the manufacturer-recommended string type and thickness: Using the wrong line is the fastest way to wear it out prematurely. Check your user manual for specs, and stick to them for best results.
• Clean the spool cavity every time you replace string: Built-up grass and debris will fray the string and cause jams, so take 30 seconds to wipe out the cavity with your small brush before installing the new spool.
• Wind the string evenly and avoid overlapping: Overlapping layers cause the spool to wobble, leading to uneven wear and jams. If you struggle to wind evenly by hand, use a cheap spool winder tool to get a tight, uniform coil every time.
• Avoid cutting near hard surfaces: Hitting concrete, rocks, fence posts, or tree trunks will wear down the string’s cutting edges in seconds. Trim at a safe distance from these surfaces, or use a guard to protect the string if you need to cut close by.
• Store your weed eater and extra string properly: Keep your weed eater in a cool, dry place out of direct sunlight, which can make nylon string brittle. Store extra string in a sealed plastic container to keep it from absorbing moisture and degrading.
• Don’t overtighten the string when winding: Tight winding creates excess friction between the string layers, causing it to break faster and making it harder for the feed mechanism to release new line. Wind it tight enough that it doesn’t come loose, but not so tight that you can’t spin the spool by hand.
• Inspect the spool and eyelet regularly: If the eyelet is sharp, cracked, or damaged, replace the spool immediately. A damaged eyelet will fray the string as it feeds through, causing it to break constantly.

Frequently Asked Questions About Replacing Weed Eater String

How often should I replace my weed eater string?

The frequency depends on how often you use your weed eater and the type of vegetation you cut. For light residential use (trimming grass around sidewalks and flower beds once a week), you’ll need to replace the string every 2 to 3 months. For heavy use (cutting thick weeds, overgrown grass, or brush weekly), plan to replace it every 1 to 2 months, or as soon as you notice the string is worn down to less than 3 inches in length.

Can I reuse old weed eater string?

No, it’s not recommended. Old string is already worn down, brittle, and may have small nicks or frays that will cause it to break almost immediately during use. Replacing string is very low cost (most rolls cost less than $10), so it’s not worth the hassle of reusing old line that will fail mid-job.

Why does my weed eater string keep breaking after I replace it?

There are a few common causes: first, you may be using string that’s too thick or too thin for your model – always check your manual for the recommended diameter. Second, the spool eyelet may be sharp or damaged, fraying the string as it feeds through. Third, you may be winding the string too tight, creating excess friction between layers. Finally, you may be cutting too close to hard surfaces like concrete or rocks, which wears down the string quickly.

Do I need to wear safety gear when replacing weed eater string?

Yes, at minimum, wear work gloves and safety glasses. The ends of new weed eater string are extremely sharp and can cause deep cuts if you handle them carelessly. Gloves also protect your hands from any sharp debris or plastic burrs on the spool housing. Safety glasses protect your eyes from flying debris when you remove the spool or clean out the cavity.

Can I replace weed eater string without removing the spool?

For some bump feed models, you can feed new string through the eyelet without removing the entire spool, but this is only a temporary fix. Over time, old string and debris will build up inside the spool cavity, causing jams and poor feed performance. For a long-lasting replacement, it’s always best to remove the spool, clean the cavity, and install a fresh spool of string.

How much string do I need for a replacement?

Most residential weed eater spools hold between 10 and 15 feet of 0.065” or 0.080” line. Check your user manual or the label on your old spool for the exact length required. It’s always a good idea to buy a full roll of replacement string (which usually holds 50-100 feet) so you have extra on hand for future replacements.

Conclusion

Learning how to replace string in weed eater is one of the easiest and most rewarding DIY maintenance tasks a homeowner can learn. It’s fast, cheap, and will save you hundreds of dollars in repair costs over the life of your tool. Whether you have a bump feed or fixed line model, following the steps in this guide will have you back to trimming your yard in minutes, no professional help needed. Remember to choose the right string type and thickness for your yard, clean the spool cavity every time you replace the line, and follow the best practices we outlined to make your new string last as long as possible. The next time your weed eater string breaks, you won’t have to panic or head to the hardware store for a new tool – you’ll have the skills to fix it yourself in no time.