How to Replace Line on Stihl Weed Eater? Line Swap Steps

Introduction

Replacing the cutting line on a Stihl weed eater is a routine maintenance task that keeps your trimmer performing at its best. Whether you own a homeowner model like the FS 40 or a professional unit such as the FS 250, the process is straightforward once you understand the type of cutting head installed on your machine. This guide walks you through everything you need to know about how to replace line on Stihl weed eater, from identifying your head style to executing a clean, tangle‑free line swap. By following the steps below you’ll save time, avoid common pitfalls, and extend the life of both the line and the trimmer head.

• Understanding Your Stihl Weed Eater Head Types
• Tools and Materials Needed
• Safety Precautions
• Step‑by‑Step Guide: Replacing Line on a Bump Feed Head
• Step‑by‑Step Guide: Replacing Line on a Fixed Line Head
• Step‑by‑Step Guide: Replacing Line on an Auto Feed Head
• Comparison Table: Head Types vs. Line Replacement Complexity
• Tips for Longer Line Life
• Common Mistakes and How to Avoid Them
• Maintenance After Line Replacement
• Frequently Asked Questions
• Conclusion

Understanding Your Stihl Weed Eater Head Types

Stihl equips its trimmers with three main cutting‑head designs. Knowing which one you have determines the exact line‑replacement procedure.

Fixed Line Head

A fixed line head (often called a “single‑line” or “dual‑line” head) holds a pre‑cut length of line that is manually threaded through the eyelets. The line does not advance automatically; you must pull new line through when the old piece wears down. This design is simple, durable, and common on entry‑level models such as the FS 38 and FS 40.

Bump Feed Head

The bump feed (or “tap‑and‑go”) head releases fresh line each time you tap the head against the ground while the engine is running. Inside the head a spool holds a reserve of line, and a spring‑loaded mechanism feeds a few centimeters with each bump. This style appears on many mid‑range and professional units, including the FS 55, FS 70, and FS 90 series.

Auto Feed Head

Auto feed heads use a centrifugal or sensor‑based system that advances line automatically as the cutting line wears. The operator does not need to bump the head. These heads are found on higher‑end professional models like the FS 130 and FS 250. They offer convenience but have more internal parts that can require occasional cleaning.

Tools and Materials Needed

Before you begin, gather the following items. Having everything at hand prevents interruptions and ensures a clean installation.

• Replacement trimmer line – match the diameter (usually 2.0 mm, 2.4 mm, or 3.0 mm) and shape (round, square, or twisted) recommended in your owner’s manual.
• Scissors or a sharp utility knife for cutting line to length.
• Clean rag or shop towel to wipe debris from the head.
• Protective gloves – nitrile or leather to protect hands from sharp line ends.
• Safety glasses – essential for eye protection during line handling.
• Small flat‑head screwdriver (optional) for heads with a retaining screw.
• Owner’s manual – for model‑specific line length and threading diagrams.

Safety Precautions

Working with a powered trimmer carries inherent risks. Observe these precautions every time you service the cutting head.

1. Turn off the engine and disconnect the spark plug lead (or remove the battery on cordless models) to prevent accidental starts.
2. Allow the cutting head to cool completely if the trimmer was recently used.
3. Wear safety glasses and gloves at all times while handling line.
4. Work on a stable, flat surface with good lighting.
5. Keep bystanders, especially children and pets, at a safe distance.
6. Never force line through eyelets; if resistance is felt, re‑examine the threading path.

Step‑by‑Step Guide: Replacing Line on a Bump Feed Head

The bump feed head is the most common style on Stihl trimmers. Follow these steps for a smooth line swap. (See Also:How To Turn On A Echo Weed Eater)

1. Remove the head cover. Press the two release tabs on the side of the head and lift the cover off. Some models have a single central latch; consult your manual if unsure.
2. Take out the spool. Pull the spool straight out of the housing. Note the direction the line is wound – most Stihl spools wind counter‑clockwise when viewed from the top.
3. Clean the spool and housing. Wipe away grass clippings, dirt, and old line fragments with a rag. A clean spool prevents binding.
4. Cut the new line. Measure two equal lengths (typically 10–12 ft each for a dual‑line head). Cut cleanly with scissors; frayed ends jam the feed mechanism.
5. Thread the first line. Insert one end of the line into the anchor hole on the spool’s inner flange. Wind the line neatly in the direction indicated by the arrow on the spool (usually counter‑clockwise). Keep tension even to avoid overlaps.
6. Thread the second line. Repeat the process for the second line, using the opposite anchor hole. Ensure both lines are wound to the same depth.
7. Leave a short tail. After winding, leave about 6 inches of line protruding from each eyelet. This tail will be pulled through the eyelets when the head is re‑assembled.
8. Re‑install the spool. Place the spool back into the housing, aligning the notches with the drive tabs. Press down until it seats firmly.
9. Feed the tails through the eyelets. Pull each tail through the corresponding eyelet on the head cover. Use a gentle tug; the line should slide freely.
10. Replace the head cover. Snap the cover back onto the housing, ensuring both release tabs engage securely.
11. Test the bump feed. Reconnect the spark plug, start the engine, and lightly tap the head on the ground. Fresh line should extend a few centimeters. If not, re‑check winding direction and tail length.

Step‑by‑Step Guide: Replacing Line on a Fixed Line Head

Fixed line heads require manual threading each time the line wears out. The procedure is quick once you’re familiar with the eyelet layout.

1. Remove the head cover. Release the latch or unscrew the retaining knob, then lift the cover away.
2. Extract the old line. Pull the worn line out of the eyelets and discard it.
3. Clean the eyelets. Use a rag to remove any debris that could snag new line.
4. Cut a single length of line. For a dual‑line head, cut two equal pieces (usually 10–12 ft each). For a single‑line head, cut one piece of the same length.
5. Thread the line. Insert one end of the line into the first eyelet, push it through the head body, and out the opposite eyelet. Pull until the line is centered, leaving equal tails on both sides.
6. Repeat for the second line (if applicable). Use the second pair of eyelets, following the same method.
7. Trim the tails. Cut the protruding ends to about 4–5 inches. This length provides enough line for the next cut without excessive waste.
8. Re‑attach the head cover. Secure the latch or tighten the retaining knob.
9. Verify line tension. Gently pull each tail; the line should be snug but not overly tight.
10. Start the trimmer. Run the engine at low speed and confirm the line feeds cleanly without vibration.

Step‑by‑Step Guide: Replacing Line on an Auto Feed Head

Auto feed heads have an internal spool that advances line automatically. Replacement involves accessing that spool.

1. Power down and disconnect the spark plug. Ensure the trimmer cannot start accidentally.
2. Remove the head assembly. Most auto feed heads unscrew counter‑clockwise from the drive shaft. Use a strap wrench if the head is tight.
3. Open the head housing. Separate the two halves by releasing the retaining clips or unscrewing the central bolt.
4. Take out the spool. Note the winding direction (usually indicated by an arrow on the spool).
5. Clean all components. Remove grass, dust, and old line fragments from the spool, spring, and housing.
6. Cut new line. Measure the length specified in the manual (often 15–20 ft for a single‑line auto feed). Cut cleanly.
7. Wind the line onto the spool. Insert the line end into the anchor slot, then wind tightly and evenly in the indicated direction. Avoid crossing turns.
8. Leave the feed tail. Allow about 6 inches of line to extend from the spool’s feed port.
9. Re‑assemble the head. Place the spool back, re‑attach the spring, and close the housing halves. Ensure clips or bolts are fully secured.
10. Re‑mount the head on the shaft. Thread it onto the drive shaft clockwise until snug.
11. Reconnect the spark plug and test. Start the engine; the auto feed should advance line as the head spins. If line does not feed, double‑check winding direction and spring placement.

Comparison Table: Head Types vs. Line Replacement Complexity

Tips for Longer Line Life

Proper line selection and handling can dramatically increase the interval between replacements.

• Match line diameter to the head. Using a line that is too thick causes binding; too thin reduces cutting efficiency and wears faster.
• Choose the right shape. Twisted or square line cuts cleaner and lasts longer than round line in heavy grass.
• Store line in a cool, dry place. UV exposure and moisture degrade nylon, making it brittle.
• Wind line under tension. Loose windings create gaps that lead to snags and uneven feed.
• Trim the line ends at a 45° angle. Angled cuts feed smoother through eyelets than blunt cuts.
• Avoid over‑revving the engine. Excessive RPM generates heat that softens the line, causing premature wear.
• Clean the head after each use. Grass buildup adds friction and can jam the feed mechanism.

Common Mistakes and How to Avoid Them

Even experienced users can slip up. Here are the most frequent errors and their fixes.

• Winding line in the wrong direction. This causes the line to jam or feed backward. Always follow the arrow on the spool or the diagram in the manual.
• Leaving tails too short. Short tails may not reach the eyelets, resulting in no line extension. Keep at least 4–6 inches.
• Using mismatched line diameter. A 3.0 mm line in a 2.4 mm head will bind; a 2.0 mm line in a 3.0 mm head will slip. Verify specifications.
• Forgetting to disconnect the spark plug. Accidental starts can cause serious injury. Make this a habit before any maintenance.
• Over‑tightening the head cover. Excess force can crack the plastic housing. Snap or tighten only until secure.
• Neglecting to clean the spool. Debris creates friction, leading to uneven feed and line breakage. A quick wipe takes seconds.

Maintenance After Line Replacement

Once the new line is installed, a few extra steps keep the trimmer running smoothly.

• Run the trimmer at low speed for 30 seconds to let the line settle into the eyelets.
• Check for vibration; excessive shake indicates an unbalanced spool or mis‑wound line.
• Inspect the head cover seal (if equipped) for cracks – a damaged seal lets debris enter the spool chamber.
• Lubricate the drive shaft splines lightly with a silicone‑based grease every 25 hours of operation.
• Record the date and line type in a maintenance log; this helps predict future replacement intervals.

Frequently Asked Questions

How often should I replace the line on my Stihl weed eater?

Replacement frequency depends on usage intensity and vegetation type. For typical residential use, expect to reload line every 2–4 hours of cutting time. Heavy commercial work may require daily line changes. (See Also:What Color Is Weed Eater Gas)

Can I use a different line diameter than the one specified in the manual?

It is not recommended. The head’s eyelets, spool geometry, and feed mechanism are engineered for a specific diameter. Using a different size can cause feeding problems, excessive wear, or damage to the head.

My bump feed head isn’t advancing line. What should I check?

First, verify the line is wound in the correct direction and that the tails are long enough to reach the eyelets. Next, inspect the spring and feed pawl inside the head for debris or damage. Clean or replace those parts if necessary.

The auto feed head seems jammed. How do I fix it?

Remove the head, open the housing, and clear any grass or line fragments from the spool and feed port. Ensure the spring is seated correctly and the line is wound tightly without overlaps. Re‑assemble and test.

Can I mix different line shapes (round, square, twisted) on the same head?

Mixing shapes is possible but not ideal. Different shapes have varying stiffness and feed characteristics, which can lead to uneven cutting and inconsistent feed. Stick to one shape per spool for best results.

What is the best way to store spare trimmer line?

Keep line in its original packaging or a sealed plastic bag, away from direct sunlight and moisture. A cool, dry garage shelf works well. Avoid storing line near chemicals or solvents that could degrade the nylon. (See Also:How To Put Line In Stihl Weed Eater)

Conclusion

Knowing how to replace line on Stihl weed eater models empowers you to keep your trimmer ready for any yard task. By identifying your head type, gathering the right tools, and following the step‑by‑step procedures outlined above, you can perform a line swap quickly and safely. Remember to match line diameter and shape to your specific head, wind the line under even tension, and observe all safety precautions. Regular cleaning, proper storage, and periodic inspection of the feed mechanism will extend both line life and overall trimmer performance. With these practices in place, you’ll spend less time troubleshooting and more time enjoying a clean, well‑trimmed landscape.