Introduction
Restringing a Stihl FS 38 weed eater is a routine maintenance task that keeps the trimmer cutting cleanly and extends the life of the cutting head. Whether you are a homeowner tackling a weekend yard project or a landscaping professional looking for a quick refresher, understanding the proper technique saves time, reduces frustration, and prevents damage to the spool or the engine. This guide walks you through every stage of the process, from gathering the right tools to selecting the best trimmer line for your specific cutting conditions. Along the way you will learn safety precautions, common pitfalls, and pro tips that make the job smoother. By the end of this article you will be confident in performing a complete restring on your FS 38 and know how to keep the trimmer running at peak performance for seasons to come.
- Understanding the Stihl FS 38 Trimmer Head
- Tools and Materials Needed
- Safety Precautions Before Restringing
- Step‑by‑Step Guide: How to String a Stihl FS38 Weed Eater
- Choosing the Right Trimmer Line
- Common Mistakes and How to Avoid Them
- Tips and Best Practices for Longer Line Life
- Troubleshooting Common Issues After Restringing
- Maintenance Schedule for the FS 38
- Frequently Asked Questions
- Conclusion
Understanding the Stihl FS 38 Trimmer Head
The FS 38 uses a fixed‑line, bump‑feed head that holds a single spool of nylon line. Unlike dual‑line heads, this design feeds line automatically when you tap the head on the ground, which simplifies the restringing process because you only have one line path to manage. The spool sits inside a plastic housing that is secured by a retaining knob. Inside the housing you will find a spring‑loaded spool that winds the line in a specific direction—usually indicated by an arrow molded into the spool. Knowing the winding direction is critical; winding the line opposite to the arrow will cause the line to feed backward or jam during operation. The head also features a small line‑guide eyelet that aligns the line as it exits the spool. Familiarizing yourself with these components before you begin will make the actual restringing steps feel intuitive.
Tools and Materials Needed
Gather the following items before you start so you do not have to interrupt the job:
- Replacement trimmer line – 0.080‑inch (2.0 mm) diameter is the factory specification for the FS 38.
- Scissors or a sharp utility knife for cutting the line to length.
- Clean rag or shop towel to wipe debris from the head.
- Protective gloves – optional but recommended to avoid cuts from the line.
- Safety glasses – always wear eye protection when working on power equipment.
- Owner’s manual – handy for reference on torque specs or specific model variations.
Having everything within arm’s reach reduces the chance of losing small parts such as the retaining knob or spring.
Safety Precautions Before Restringing
Before you touch the trimmer head, ensure the engine is completely off and the spark plug wire is disconnected. This eliminates any risk of accidental start‑up while your hands are near the rotating components. Allow the engine to cool for at least five minutes if it has been running recently; hot metal can cause burns. Wear safety glasses to protect your eyes from any stray line fragments that may snap during removal. Gloves protect your hands from the sharp edges of the nylon line and from the plastic housing. Finally, work on a stable, flat surface—preferably a workbench or a clean patch of grass—so the trimmer does not tip over while you are handling the spool.
Step‑by‑Step Guide: How to String a Stihl FS38 Weed Eater
- Remove the retaining knob. Turn the knob counter‑clockwise until it loosens completely. Set the knob aside in a safe place.
- Take off the spool housing. Lift the outer housing straight up. The spool and spring will remain inside the housing; keep them together to avoid losing the spring.
- Extract the old line. Pull any remaining line from the spool. If the line is tangled, gently unwind it rather than forcing it, which could damage the spool.
- Inspect the spool and spring. Check for cracks, excessive wear, or a weakened spring. Replace the spool if you see damage; a compromised spool will cause feeding problems later.
- Cut the new line to length. Measure approximately 10 feet (3 m) of 0.080‑inch line. Cut cleanly with scissors or a knife. A clean cut prevents fraying that can jam the feed mechanism.
- Insert the line into the spool. Locate the anchor hole on the spool (usually a small notch). Feed one end of the line through the hole and pull it through until the line is centered, leaving equal lengths on both sides.
- Wind the line following the arrow. Hold the spool steady and wind the line in the direction indicated by the arrow molded on the spool. Keep the wraps tight and even, avoiding overlaps. Continue winding until you have about 6 inches (15 cm) of line remaining on each side.
- Secure the line ends. Insert the two free ends into the line‑guide eyelets on the housing. This holds the line in place while you reassemble the head.
- Reinstall the spool and housing. Place the spool back into the housing, ensuring the spring seats correctly. Align the housing with the drive shaft and press down firmly.
- Replace the retaining knob. Thread the knob onto the shaft and tighten clockwise until snug. Do not overtighten; the knob should be firm but still removable by hand.
- Test the feed. Reconnect the spark plug wire, start the engine, and gently tap the head on the ground. The line should advance smoothly. If it does not, repeat steps 5‑9, checking for proper winding direction.
Choosing the Right Trimmer Line
Not all nylon lines perform the same. The FS 38 is designed for 0.080‑inch line, but you can select different profiles to match your cutting conditions. The table below compares the most common line shapes available for this trimmer.
| Line Profile | Best Use | Durability | Cutting Aggressiveness | Noise Level |
|---|---|---|---|---|
| Round | General purpose, light grass | High | Moderate | Low |
| Square | Thick weeds, brush | Medium | High | Medium |
| Twisted (Helical) | Mixed grass and light brush | Medium‑High | High | Low‑Medium |
| Serrated / Saw‑tooth | Heavy brush, small saplings | Low‑Medium | Very High | High |
For most residential lawns, a round or twisted line offers the best balance of life and cutting speed. If you frequently tackle thick weeds or light brush, a square profile will cut faster but will wear out sooner. Always stay within the 0.080‑inch diameter; thicker line can overload the motor and cause premature wear.
Common Mistakes and How to Avoid Them
- Winding the line backward. Always follow the arrow on the spool. If you wind opposite, the bump‑feed will pull line into the head instead of feeding it out.
- Using the wrong line diameter. Thicker line (0.095 in or larger) stresses the engine and can cause the head to jam. Stick to the manufacturer‑specified 0.080 in.
- Over‑filling the spool. Leaving too little tail line prevents the bump‑feed from gripping the line. Leave roughly 6 inches on each side after winding.
- Forgetting to seat the spring. A mis‑seated spring will cause the spool to spin freely without feeding line. Double‑check the spring position before snapping the housing shut.
- Neglecting to clean the head. Grass clippings and dirt can accumulate in the line guide, creating friction. Wipe the housing clean each time you restring.
Tips and Best Practices for Longer Line Life
- Store spare line in a cool, dry place; UV exposure makes nylon brittle.
- Soak new line in water for 10 minutes before winding; this reduces stiffness and helps the line lay flat on the spool.
- Avoid tapping the head on hard surfaces like concrete; use a grassy area to reduce shock to the spool.
- Trim at a slight angle rather than straight down; this reduces the load on the line and produces a cleaner cut.
- Inspect the line after each use. Replace it when you see significant fraying or when the line length drops below 2 inches.
Troubleshooting Common Issues After Restringing
Even with careful work, you may encounter a few hiccups. Here are the most frequent problems and quick fixes:
- Line does not advance when bumped. Verify the winding direction, ensure the line tails are seated in the guide eyelets, and confirm the spring is properly seated.
- Line feeds too quickly and runs out fast. The spool may be over‑wound. Unwind a few turns so the line has room to expand during feeding.
- Excessive vibration or noise. Check that the retaining knob is tight but not stripped. A loose knob allows the head to wobble.
- Engine stalls when the head contacts heavy growth. This often indicates the line is too thick or the engine air filter is dirty. Re‑check line diameter and clean the filter.
Maintenance Schedule for the FS 38
Regular upkeep beyond restringing keeps the trimmer reliable. Follow this simple schedule:
- Every use: Inspect line length, clean debris from the head, check for loose bolts.
- Every 10 hours: Clean or replace the air filter, inspect the spark plug, lubricate the drive shaft if the model calls for it.
- Every 25 hours: Replace the spark plug, check the fuel filter, examine the muffler for carbon buildup.
- Annually: Replace the fuel lines, inspect the carburetor diaphragm, and perform a full throttle response test.
Keeping a log of hours and tasks helps you stay ahead of wear and avoids unexpected downtime during the growing season.
Frequently Asked Questions
How often should I restring my Stihl FS 38?
Restring whenever the line wears down to less than 2 inches or when you notice reduced cutting performance. For typical residential use this may be every 2‑3 hours of run time.
Can I use 0.095‑inch line on the FS 38?
Stihl specifies 0.080‑inch line for the FS 38. Using thicker line increases load on the engine and can cause overheating or head damage. Stick to the recommended diameter.
Why does the line keep jamming after I restring?
Jamming is usually caused by winding the line opposite to the arrow, overlapping wraps, or not seating the line ends in the guide eyelets. Re‑wind carefully following the arrow and keep wraps tight and even.
Do I need to lubricate the spool or spring?
No. The spool and spring are designed to run dry. Adding oil or grease attracts dirt and can cause the line to slip.
What is the best line for edging along sidewalks?
A twisted or square profile line provides a sharper edge for clean cuts along hard surfaces. Round line works but may leave a slightly ragged edge.
Conclusion
Restringing a Stihl FS 38 weed eater is a straightforward task once you understand the head mechanics, follow the correct winding direction, and use the proper 0.080‑inch line. By gathering the right tools, observing safety precautions, and following the step‑by‑step guide outlined above, you can complete the job in under ten minutes and keep your trimmer cutting efficiently. Selecting a line profile that matches your yard conditions, avoiding common mistakes, and adhering to a simple maintenance schedule will extend both line life and overall trimmer longevity. With these practices in place, you’ll spend less time fussing with the head and more time enjoying a well‑manicured lawn.