How to Replace Stihl Weed Eater String? Easy Replacement Guide

Introduction

Replacing the string on your Stihl weed eater is one of those maintenance tasks that seems simple until you actually try to do it. If you’ve ever found yourself staring at a tangled mess of string, wondering which end goes where or why the new line won’t feed properly, you’re not alone. This guide will walk you through everything you need to know about how to replace Stihl weed eater string, from choosing the right type to troubleshooting common problems.

Table of Contents

• Why Replace Your Weed Eater String?
• Tools and Materials You’ll Need
• Understanding Different String Types
• Preparing Your Stihl Weed Eater
• Removing the Old String
• Measuring and Cutting New String
• Spooling the New String
• Installing the New Spool
• Testing Your Work
• Common Mistakes to Avoid
• Troubleshooting Problems
• Maintenance Tips
• When to Replace vs. When to Repair
• Professional Tips and Best Practices
• Frequently Asked Questions
• Conclusion

Why Replace Your Weed Eater String?

The string on your Stihl weed eater doesn’t last forever. Over time, it becomes worn, frayed, and less effective at cutting through tough vegetation. Here are the main reasons why you should replace your string regularly:

• Reduced cutting performance – Worn string doesn’t cut cleanly and may leave behind ragged edges
• Increased vibration – Dull or damaged string causes excessive vibration that can damage your tool
• String breakage – Old string is more prone to breaking during use
• Poor line feed – Worn string may not advance properly from the spool
• Safety concerns – Damaged string can snap unexpectedly and pose a safety risk

Most manufacturers recommend replacing the string every 10-20 hours of use, depending on the thickness and conditions you’re working in.

Tools and Materials You’ll Need

Before you begin learning how to replace Stihl weed eater string, gather these essential items:

• New replacement string (appropriate gauge and length for your model)
• Small flathead screwdriver
• Clean cloth or rag
• Optional: Needle-nose pliers
• Optional: String cutter or sharp scissors

Make sure you have the correct replacement string for your specific Stihl model. Using the wrong type can cause feeding problems or damage to your trimmer.

Understanding Different String Types

Not all weed eater strings are created equal. Your choice of string can significantly impact performance and durability. Here’s what you need to know:

Cord Cross-Sections

Weed eater string comes in various cross-sectional shapes:

• Round – Most common type, good general purpose string
• Square – Provides more cutting edges, better for thick weeds
• Star-shaped – Excellent cutting power, wears longer
• Triangular – Good balance of durability and cutting ability

String Thickness (Gauge)

String thickness is measured in gauge numbers – the higher the number, the thicker the string:

String Material

Most weed eater string is made from nylon, but there are variations:

• Standard nylon – Most common, good balance of durability and flexibility
• Reinforced nylon – Contains fiberglass or other materials for extra strength
• Polytetrafluoroethylene (PTFE) – Reduces friction and extends string life

Preparing Your Stihl Weed Eater

Before you start the replacement process, take these important safety steps:

Safety First

Always follow proper safety procedures when working with power tools:

1. Disconnect the power source – Remove the spark plug wire for gas models or disconnect the battery for electric models
2. Allow the tool to cool – Never work on a hot engine or recently used trimmer
3. Work in a clean area – Clear away debris and ensure good lighting
4. Wear protective gear – Safety glasses and work gloves are recommended

Identify Your Model

Check your Stihl model number to ensure you get the correct replacement string. The model number is typically located on a decal near the engine or on the handle. Common Stihl trimmer models include:

• FS 38, FS 55, FS 70, FS 90 series
• FSC 55, FSA 60, FSA 90 series
• HT 32, HT 55, HT 70 series (hedge trimmers)

Removing the Old String

Now that you’re prepared, here’s how to remove the old string from your Stihl weed eater:

Method 1: Bump Feed Head

For most Stihl trimmers with bump feed heads:

1. Remove the cap – Twist the cap counterclockwise and lift it off
2. Take out the spool – Pull the spool straight up and out of the housing
3. Remove remaining string – Pull any remaining string through the eyelets
4. Clean the housing – Use a clean cloth to remove debris and old string fragments

Method 2: Auto Feed Head

For automatic feed systems:

1. Turn off the tool – Ensure power is completely disconnected
2. Remove the cap – Some models require removing screws to access the spool
3. Extract the spool – Carefully pull the spool assembly out
4. Clean thoroughly – Remove all old string and debris

Method 3: Fixed Line Head

For fixed line heads:

1. Remove the head – Follow manufacturer instructions for your specific model
2. Extract old line – Pull the old line completely out
3. Clean the head – Remove all debris before installing new line

Measuring and Cutting New String

Proper measurement is crucial for successful string replacement. Here’s how to measure correctly:

Determining String Length

The amount of string you need depends on your spool size:

• Small spools (6"-8" diameter) – Need approximately 15-20 feet of string
• Medium spools (8"-10" diameter) – Need approximately 20-25 feet of string
• Large spools (10"+ diameter) – Need approximately 25-30 feet of string

Cutting Technique

Follow these steps for accurate cutting:

1. Use a straight edge – A ruler or measuring tape works best
2. Mark before cutting – Make a clear mark at your measurement point
3. Cut cleanly – Use sharp scissors or a utility knife for a clean cut
4. Check twice – Measure twice, cut once to avoid wasting string

String Color Coding

Some Stihl strings come color-coded for easy identification:

• Red – Heavy-duty applications
• Blue – Medium-duty applications
• Green – Light-duty applications
• Yellow – Specialty applications

Spooling the New String

This is where many people struggle with how to replace Stihl weed eater string. Proper spooling ensures smooth operation:

Single-Spool Technique

For single-line systems:

1. Start at the center – Begin winding from the center hole outward
2. Wind in the correct direction – Follow the arrow on the spool if present
3. Maintain consistent tension – Keep the string taut but not overly tight
4. Leave proper tail length – Leave about 6 inches extending from the spool
5. Don’t overfill – Leave space at the edges to prevent binding

Dual-Spool Technique

For dual-line systems:

1. Use two separate spools – Wind each line on its own spool
2. Maintain equal tension – Both lines should have similar tension
3. Cross-wind carefully – Ensure lines don’t cross or tangle
4. Test rotation – Spin the spool to check for smooth movement

Spooling Best Practices

Keep these tips in mind while spooling:

• Work in a clean environment – Dust and debris can interfere with winding
• Use even pressure – Inconsistent pressure creates uneven windings
• Check for twists – Remove any twists before continuing
• Verify direction – Incorrect winding direction causes feeding problems

Installing the New Spool

With your spool properly wound, it’s time to install it back into your Stihl weed eater:

Basic Installation Steps

1. Insert the spool – Place it back into the housing, ensuring proper alignment
2. Route the string – Thread the string ends through the appropriate eyelets
3. Secure the cap – Replace and tighten the cap according to manufacturer specifications
4. Check alignment – Ensure everything sits flush and properly aligned

Securing the String Ends

Proper string end management prevents future problems:

• Leave adequate length – Typically 6-8 inches extending beyond the eyelet
• Avoid sharp cuts – Cut ends should be clean but not pointed
• Check for kinks – Ensure no kinks or bends near the eyelet
• Test feed mechanism – Gently pull string to verify smooth feeding

Testing Your Work

After completing the installation, thorough testing is essential:

Initial Test Run

Perform this step-by-step test:

1. Reconnect power – Reattach spark plug wire or battery connection
2. Start the tool – Follow normal starting procedure for your model
3. Observe string behavior – Watch for smooth feeding and proper rotation
4. Check for vibrations – Excessive vibration indicates improper installation
5. Listen for unusual sounds – Grinding or clicking suggests problems

Practical Testing

Test in actual working conditions:

• Start with light material – Grass clippings or light weeds first
• Check string advancement – Verify the string feeds when needed
• Monitor performance – Compare to previous performance
• Look for wear patterns – Uneven wear indicates spooling issues

Common Mistakes to Avoid

Even experienced users make mistakes when learning how to replace Stihl weed eater string. Here are the most frequent errors:

Winding Errors

These mistakes cause immediate problems:

• Wrong winding direction – Causes binding and feeding issues
• Inconsistent tension – Creates uneven windings that tangle
• Overfilling the spool – Leaves no room for expansion during use
• Underfilling the spool – Results in frequent string changes

Installation Errors

Common installation mistakes include:

• Misaligned spool – Causes vibration and poor performance
• Improper string routing – String binds instead of feeding smoothly
• Loose cap installation – Allows debris entry and string escape
• Incorrect string length – Too short requires frequent changes; too long causes tangling

Testing Oversights

Skipping proper testing leads to field failures:

• Rushing the process – Taking shortcuts results in rework
• Ignoring warning signs – Vibrations or noises indicate problems
• Not checking both lines – Dual-line systems require equal attention

Troubleshooting Problems

If you encounter issues after replacing your string, here are solutions to common problems:

Feeding Issues

If the string won’t feed properly:

• Check winding direction – Reverse if necessary
• Verify string path – Ensure it follows the correct route
• Inspect eyelets – Clear any debris blocking the string path
• Adjust tension – May need to rewind with different tension

Vibration Problems

Excessive vibration usually indicates:

• Improper spool installation – Reinstall checking alignment
• Unbalanced windings – Rewind with even tension
• Damaged spool – Replace if cracked or warped

String Breakage

Frequent string breakage suggests:

• String too thin – Upgrade to heavier gauge
• Sharp contact surfaces – Check for burrs or sharp edges
• Incorrect technique – Review proper trimming methods

Maintenance Tips

Proper maintenance extends string life and prevents premature replacement:

Daily Maintenance

After each use:

• Clean the head – Remove grass clippings and debris
• Check string condition – Look for fraying or damage
• Inspect eyelets – Ensure they’re clean and undamaged

Weekly Maintenance

Regular upkeep includes:

• Deep clean the spool – Remove built-up debris
• Check cap seal – Ensure it’s tight and secure
• Examine string wear – Replace if showing significant wear

Seasonal Maintenance

Longer-term care:

• Complete string replacement – Even if not broken, replace seasonally
• Inspect the entire head assembly – Look for cracks or damage
• Store properly – Keep in dry, temperature-controlled environment

When to Replace vs. When to Repair

Sometimes the problem isn’t the string but something else entirely. Here’s how to tell what needs attention:

Replace the String When:

• String is consistently breaking during normal use
• String won’t advance even after adjustment
• String is severely frayed or damaged
• You’ve exceeded recommended usage hours

Repair Other Components When:

• Cap won’t stay secured properly
• Sprocket or gear mechanism is damaged
• Housing shows cracks or significant wear
• Fuel line or electrical connections are faulty

Professional Service Indicators

Consider professional service for:

• Motor or engine problems – Unusual noises, loss of power
• Transmission issues – Gears slipping or not engaging
• Fuel system problems – Starting difficulties, fuel leaks
• Electrical malfunctions – Intermittent operation, no power

Professional Tips and Best Practices

Here are expert-level insights to improve your string replacement skills:

Advanced Spooling Techniques

Professional landscapers use these methods:

• Pre-measure exactly – Use a measured length of string as a guide
• Mark the spool – Use tape to indicate proper fill level
• Use a spooling jig – Homemade or commercial tools ensure consistency
• Practice tension control – Develop muscle memory for proper tension

String Selection Strategies

Choose string based on specific applications:

• Thick, woody weeds – Use square or star-shaped string in 0.095" gauge
• Fine grass trimming – Round string in 0.065" or 0.080" works well
• Commercial applications – Consider reinforced string for durability
• Delicate landscaping – Lighter gauge prevents damage to plants

Efficiency Tips

Save time and money with these shortcuts:

• Buy string in bulk – Larger quantities reduce per-foot cost
• Keep multiple spools ready – Pre-wound spools save time
• Track usage patterns – Note which areas require more frequent changes
• Rotate stock – Use older string first to prevent degradation

Frequently Asked Questions

Can I use any brand of string on my Stihl weed eater?

While Stihl recommends using genuine Stihl replacement parts, many quality aftermarket strings work well. The key is matching the correct gauge and length for your specific model. However, using genuine Stihl string ensures optimal compatibility and performance.

How often should I replace the string?

Replace string when you notice decreased cutting performance, frequent breakages, or after approximately 10-20 hours of use. For regular users, this typically means replacing every few months during peak growing season.

What happens if I use string that’s too thick?

Using string that’s too thick can overload the motor, cause excessive vibration, prevent proper feeding, and potentially damage internal components. Always check your owner’s manual for the recommended gauge.

Do I need to replace both strings at the same time?

Yes, always replace both strings simultaneously. Using mismatched strings creates imbalance that leads to vibration, poor performance, and premature wear of other components.

Can I repair a broken string instead of replacing it?

It’s not recommended. Tied knots create weak points that will break again, and improper repairs can cause dangerous flying debris. Always replace broken string with new material.

Why does my new string keep breaking?

Several factors could cause this: using the wrong gauge, improper spooling technique, hitting hard objects, or excessive tension. Check each of these elements systematically to identify the cause.

How do I know what gauge string my Stihl uses?

Check your owner’s manual or look for specifications printed on the original string packaging. You can also contact Stihl customer service with your model number for confirmation.

Should I wind the string clockwise or counterclockwise?

This varies by model. Always check for arrows on the spool indicating winding direction, or consult your manual. Incorrect winding direction is a common cause of feeding problems.

What’s the difference between bump feed and auto feed?

Bump feed requires you to manually tap the head on the ground to advance new string. Auto feed systems automatically dispense string as needed. Both require periodic string replacement, but the installation process differs.

Can I replace the string myself or should I take it to a professional?

String replacement is a straightforward DIY task that most users can handle. However, if you’re uncomfortable with power tools or encounter persistent problems, don’t hesitate to seek professional help.

Conclusion

Learning how to replace Stihl weed eater string is an essential skill for any homeowner or landscaper. While the process may seem intimidating at first, following these steps systematically will help you achieve professional results every time.

Remember that practice makes perfect. Your first few attempts might take longer than expected, but with experience, you’ll be able to complete the task quickly and efficiently. Pay attention to the details – proper winding direction, correct tension, and adequate testing can make the difference between a successful replacement and frustrating repeated attempts.

By maintaining your weed eater properly and replacing the string according to schedule, you’ll enjoy better performance, longer tool life, and a cleaner, more professional-looking lawn and garden. Don’t forget to consult your owner’s manual for model-specific instructions, and don’t hesitate to reach out to Stihl customer support if you encounter persistent issues.

With the knowledge gained from this guide, you now have everything you need to confidently tackle string replacement on your Stihl weed eater. Happy trimming!