Introduction
Stihl is one of the most trusted brands in outdoor power equipment, and its weed eaters (also called trimmers) are a staple for both residential homeowners and commercial landscapers. Over time, the trimmer line on your Stihl weed eater will wear down from contact with rocks, concrete, and dense vegetation, requiring replacement. Many users struggle with putting new line in correctly, leading to frustrating issues like line jams, uneven cutting, and even damage to the trimmer head. Whether you’re a first-time Stihl owner or have been winding trimmer line for years, this guide covers the pro winding method to help you complete the task quickly, correctly, and without hassle. We’ll walk through every step, from gathering tools to testing your newly loaded weed eater, plus answer common questions to ensure you never have to guess how to put line in Stihl weed eater again.
- Understanding Your Stihl Weed Eater Trimmer Line System
- Tools and Materials You’ll Need
- Safety Precautions Before Replacing Trimmer Line
- Step-by-Step Guide to Putting Line in a Stihl Weed Eater
- Pro Winding Tips for Different Stihl Head Types
- Comparison Table: Single Line vs. Dual Line vs. Square Line for Stihl Weed Eaters
- Common Mistakes to Avoid When Winding Stihl Trimmer Line
- Troubleshooting Common Trimmer Line Issues
- Tips for Extending Trimmer Line Lifespan
- Frequently Asked Questions
- Conclusion
Understanding Your Stihl Weed Eater Trimmer Line System
Before you start replacing your trimmer line, it’s helpful to understand the basic components of your Stihl weed eater’s line system. Stihl uses a few different trimmer head designs, each with specific line winding and feeding requirements. Knowing your head type will help you follow the correct steps for your model and avoid common errors.
Types of Stihl Trimmer Lines
Stihl offers several types of trimmer line, each designed for specific cutting tasks:
- Round line: The most common all-purpose line, ideal for cutting grass and small, soft weeds. It wears evenly and works well for light residential use.
- Square line: Has sharp edges on all sides that slice through thicker weeds and light brush. It’s more aggressive than round line but wears down faster on hard surfaces like concrete.
- Serrated line: Features small teeth along its length that shred dense overgrowth and woody brush. It’s best for heavy-duty commercial use but has the shortest lifespan of all line types.
- Cross-cut line: A heavy-duty option with a cross-shaped profile that cuts through thick vegetation quickly. It’s designed for professional landscapers tackling very tough jobs.
While Stihl recommends using its branded trimmer line for optimal performance, third-party lines of the correct diameter will work for most models as long as they meet the manufacturer’s specifications.
Common Trimmer Head Models for Stihl Weed Eaters
Stihl’s most popular trimmer head models include the AutoCut 25-2 (dual-line, automatic feed for residential use), AutoCut 37-2 (larger dual-line for medium to large properties), TrimCut 31-2 (single-line, manual feed for light-duty use), and the Mowing Head (for heavy-duty grass cutting with a single thick line). While each head has slightly different disassembly steps, the core pro winding method is consistent across all models, making this guide useful for almost every Stihl weed eater owner.
Tools and Materials You’ll Need
Replacing your Stihl trimmer line requires only a few basic tools, most of which you likely already have in your home toolkit:
- Replacement Stihl trimmer line (correct diameter for your model; check your user manual or the old line for sizing)
- Work gloves (to protect your hands from sharp line edges)
- Small flathead screwdriver or dedicated trimmer line removal tool
- Tape measure or ruler
- Clean rags (to wipe debris from the trimmer head)
- Silicone-based trimmer line lubricant (optional, to extend line lifespan)
You won’t need any special or expensive tools to complete this task, making it a cost-effective DIY repair for your Stihl weed eater.
Safety Precautions Before Replacing Trimmer Line
Taking a few simple safety steps before you start working on your weed eater will prevent injury and avoid accidental damage to your equipment:
- Always disconnect the spark plug wire from the spark plug if you have a gas-powered Stihl weed eater, or remove the battery pack entirely for cordless models. This prevents the trimmer from starting accidentally while you work.
- Wear work gloves to avoid cuts from the sharp ends of trimmer line, which can cause deep skin injuries if handled without protection.
- Work in a well-lit, flat area so you don’t lose small parts like the retaining cap or spool alignment tabs.
- Never work on the trimmer while it is running or connected to a power source, even if you are just making quick adjustments.
Following these precautions takes less than a minute and will keep you safe while you work.
Step-by-Step Guide to Putting Line in a Stihl Weed Eater
This step-by-step guide uses the pro winding method recommended by Stihl to ensure tangle-free line installation and optimal performance. Follow these steps in order for the best results.
Preparing the Weed Eater for Line Replacement
- Place the weed eater on a flat, stable work surface. For gas-powered models, set it with the engine side down; for cordless models, place it with the battery compartment facing down to prevent accidental activation.
- Disconnect the spark plug wire from the spark plug if you have a gas-powered Stihl weed eater, or remove the battery pack entirely for cordless models. This step prevents the trimmer from starting accidentally while you work.
- Rotate the trimmer head so the line spool is facing upward, and use a clean rag to wipe away any grass clippings, dirt, or debris from around the head and spool area.
Removing the Old Trimmer Line
- Locate the retaining cap or ring on the bottom of the trimmer head. Most Stihl models have a small release tab that you press to pop the cap off, or a retaining ring that twists counterclockwise to remove.
- Pull the old line spool out of the head cavity. If the spool is stuck due to tangled line or debris, use a small flathead screwdriver to gently pry it loose, taking care not to crack the spool or damage the head’s internal slots.
- Pull all remaining old line off the spool, then wipe both the spool and the head cavity with a clean rag to remove built-up grass, dirt, and old lubricant.
- Inspect the spool for cracks, warping, or worn notches. If the spool is damaged, replace it with a Stihl-approved replacement before installing new line, as a worn spool will cause line jams and poor feeding.
Winding the Trimmer Line the Pro Way
The most common cause of trimmer line jams and poor performance is incorrect winding. This pro method ensures tight, tangle-free winding every time, regardless of your Stihl head model.
- Cut your replacement trimmer line to the correct length. For single-line heads, cut one length of line; for dual-line heads, cut two equal lengths. As a general rule, cut each piece to 1.5 times the diameter of your line spool, plus 6 inches for the working ends. For example, if your spool is 6 inches in diameter, cut two 15-inch lengths for a dual-line head.
- Flip the line spool over and locate the small winding direction arrow printed on the underside. This arrow indicates the correct direction to wind the line (almost always clockwise when viewed from the bottom of the spool for Stihl models).
- Insert the end of the first line into the small notch on the edge of the spool, then wind the line tightly and evenly in the direction of the arrow. Do not overlap the line as you wind, as this creates bumps that will catch on the trimmer head’s internal parts. Wind until there is a 1/4-inch gap between the wound line and the edge of the spool.
- If you are using a dual-line head, repeat the winding process with the second length of line, using the same direction and leaving the same 1/4-inch gap between the wound line and the spool edge.
- Once the line is fully wound, tuck the loose ends of the line into the small notches on the edge of the spool to hold them in place during installation. This prevents the ends from coming loose and tangling while you fit the spool into the head.
Installing the New Line in the Trimmer Head
- Align the small tabs on the line spool with the corresponding slots in the trimmer head cavity. These tabs ensure the spool is seated correctly so the line feeds out of the proper slots.
- Insert the spool into the head cavity, pressing gently until it clicks into place. Do not force the spool; if it does not fit, rotate it slightly until the tabs align with the slots.
- Pull both line ends (for dual-line heads) or the single line end (for single-line heads) out of the feed slots on the sides of the head. For dual-line heads, pull both ends to an equal length of 6 to 8 inches to ensure even cutting. For single-line heads, pull the line out to the length recommended in your user manual, usually 6 to 10 inches.
- If your trimmer head has a line retention clip or bump knob, make sure it is properly seated against the line ends before moving on to reassembly.
Reassembling and Testing the Weed Eater
- Replace the retaining cap or ring on the bottom of the trimmer head, twisting it clockwise until it is snug or clicks into place. Do not over-tighten the cap, as this can crack the plastic or damage the spool.
- Reconnect the spark plug wire to the spark plug for gas-powered models, or reinsert the battery pack for cordless models.
- Test the line feed: for automatic feed heads like the AutoCut, turn the trimmer on and bump the head lightly on the ground to confirm the line extends correctly. For manual feed heads, pull the line out to the correct length and confirm it stays in place without slipping back into the head.
- Test cut a small patch of grass or weeds to confirm the line cuts evenly, with no wobbling, jamming, or uneven cutting. If the line does not feed, jams, or cuts poorly, disassemble the head and double-check that the line was wound in the correct direction and is seated properly.
Pro Winding Tips for Different Stihl Head Types
While the core winding method is the same for all Stihl trimmer heads, these model-specific tips will help you get the best performance from your equipment:
- AutoCut Heads (e.g., AutoCut 25-2, AutoCut 37-2): These automatic feed heads rely on centrifugal force to extend the line when you bump the head. Wind the line as tightly as possible to prevent bunching inside the spool, and only use the line diameter recommended for your specific AutoCut model. Thicker line can jam the feed mechanism, while thinner line will break easily during use.
- TrimCut Heads (e.g., TrimCut 31-2): These manual feed heads require you to pull the line out to the correct length before each use. Wind the line tightly to prevent it from slipping back into the head while you’re cutting, and check the line length regularly to ensure it’s not too short to cut effectively.
- Mowing Heads: These heavy-duty heads use a single thick line for cutting grass and light vegetation. Wind the line in the direction of the arrow on the spool, and leave a small gap between the wound line and the spool edge to prevent the line from rubbing against the head during use, which causes excess wear.
- All Head Types: Never overfill the spool with line. If you wind too much line on the spool, it will bulge and won’t fit back into the head cavity, leading to poor performance and jams. Stick to the recommended line length for your spool size.
Comparison Table: Single Line vs. Dual Line vs. Square Line for Stihl Weed Eaters
Choosing the right trimmer line for your Stihl weed eater will improve cutting performance and extend the life of your equipment. Use this comparison table to select the best line for your needs:
| Line Type | Best Use Case | Cutting Performance | Winding Difficulty | Lifespan |
|---|---|---|---|---|
| Single Round Line | Light residential use, grass and small weeds | Even cutting for soft vegetation, less aggressive on hard surfaces | Easy, minimal winding steps | Longest, as it wears evenly |
| Dual Round Line | Medium residential use, mixed grass and weeds | Faster cutting than single line, good coverage | Moderate, requires two equal lengths of line | Moderate, wears faster than single line |
| Square Line | Thick weeds, brush, and commercial use | Aggressive cutting, sharp edges slice through dense vegetation | Moderate, same winding process as round line | Shorter, edges wear down faster on hard surfaces |
| Serrated Line | Heavy overgrowth, woody brush | Teeth shred vegetation quickly, ideal for tough jobs | Slightly harder, as serrated edges can catch if not wound tightly | Shortest, teeth wear down quickly |
Common Mistakes to Avoid When Winding Stihl Trimmer Line
Even experienced users make these common errors when replacing trimmer line, leading to poor performance and unnecessary frustration. Avoid these mistakes to get the most out of your Stihl weed eater:
- Winding the line in the wrong direction: This is the most frequent mistake users make. Winding the line backwards causes it to tangle inside the spool, jam the feed mechanism, and prevent the line from extending during use. Always check the arrow on the bottom of the spool before you start winding.
- Overlapping the line while winding: Overlapping creates bumps and uneven layers that catch on the trimmer head’s internal parts, causing jams and uneven line feed. Wind the line tightly and evenly, with each layer sitting flat against the previous one.
- Using the wrong line diameter: Line that is too thick will not fit in the head cavity or will jam the feed mechanism, while line that is too thin will break easily and provide poor cutting performance. Always check your user manual for the recommended line diameter for your model.
- Not securing the line ends in the spool notches: If you don’t tuck the loose line ends into the spool’s edge notches, they will come loose while you’re installing the spool, leading to tangles and a messy winding job.
- Over-tightening the retaining cap: Tightening the cap too hard can crack the plastic cap or warp the spool, leading to poor performance and the need for replacement parts. Tighten the cap until it is snug, then stop.
Troubleshooting Common Trimmer Line Issues
Even with correct installation, you may run into occasional issues with your Stihl trimmer line. Here are quick fixes for the most common problems:
- Line won’t feed out: Check that the line is wound in the correct direction, that the spool is seated properly in the head, and that the line ends are pulled out to the correct length. For AutoCut heads, make sure the bump knob is not stuck.
- Line breaks frequently: This is usually caused by using line that is too thin for your model, or cutting near hard surfaces. Switch to the recommended line diameter and avoid cutting near concrete, rocks, and curbs.
- Uneven cutting: This is often due to uneven line lengths on dual-line heads, or worn line. Pull both line ends to equal length for dual-line heads, and replace the line if it is frayed or worn down.
- Vibration during use: This is usually caused by an unbalanced spool, either from uneven winding or a damaged spool. Remove the spool, rewind the line tightly and evenly, or replace the spool if it is cracked or warped.
Tips for Extending Trimmer Line Lifespan
Replacing trimmer line is an ongoing cost for weed eater owners, but these simple tips will help you get more use out of each spool of line:
- Avoid cutting near hard surfaces like concrete, rocks, curbs, and tree trunks, as these wear down the line’s cutting edges much faster than soft grass and soil.
- Wipe the line clean with a dry rag after each use to remove grass clippings, dirt, and debris that can weaken the line over time.
- Store spare trimmer line in a cool, dry place away from direct sunlight, as UV exposure makes line brittle and prone to breaking.
- Match your line type to your cutting job: use light round line for grass and small weeds, and reserve heavy serrated or square line for thick brush and overgrowth. Using heavy line for light jobs will wear it down unnecessarily fast.
- Apply a small amount of silicone-based lubricant to the line every few uses to reduce friction and prevent the line from drying out and becoming brittle.
Frequently Asked Questions
How often should I replace the line in my Stihl weed eater?
The frequency of line replacement depends on how often you use your trimmer and what you are cutting. For light residential use (1 to 2 hours per week), you will need to replace the line every 1 to 2 months. For commercial use (8 or more hours per day), you may need to replace the line weekly. You will know it is time to replace the line when it is shorter than 3 inches, frayed, or worn down so much that it no longer cuts vegetation effectively.
What happens if I wind the line in the wrong direction?
Winding the line in the wrong direction will cause it to tangle inside the spool, jam the feed mechanism, and prevent the line from extending when you bump the head or pull it manually. In severe cases, this can damage the trimmer head’s internal gears, leading to costly repairs. Always check the winding direction arrow on the bottom of the spool before you start winding to avoid this issue.
Why is my new line getting stuck in the trimmer head?
Line jams after replacement are almost always caused by two errors: overlapping the line while winding, or winding the line too loosely. Overlapping creates bumps that catch on the head’s internal parts, while loose winding causes the line to bunch up and block the feed slots. To fix this, remove the spool, unwind the line, and rewind it tightly and evenly in the correct direction with no overlaps.
How do I know what diameter trimmer line to use for my Stihl weed eater?
The correct line diameter for your Stihl weed eater is listed in your user manual, which you can access online for free on the Stihl website if you do not have a physical copy. Common line diameters include .080 inch for light-duty residential trimmers, .095 inch for medium-duty models, and .105 inch for heavy-duty commercial trimmers. Using the wrong diameter can cause poor performance, frequent jams, and damage to the trimmer head.
How do I adjust the bump feed on my Stihl AutoCut head after replacing the line?
Most Stihl AutoCut heads have a self-adjusting feed mechanism, so no manual adjustment is needed after replacing the line. If the line is not feeding correctly, first confirm that you pulled the line ends out to the correct 6 to 8 inch length, and that the spool is seated properly in the head. If it still does not feed, double-check that the line was wound in the correct direction and that there are no tangles inside the spool.
Conclusion
Putting line in a Stihl weed eater is a simple task when you follow the right steps and use the pro winding method outlined in this guide. By taking the time to prepare properly, wind the line tightly and evenly in the correct direction, and avoid common mistakes, you can load your trimmer in minutes and ensure it performs at its best for every use. Whether you are maintaining a small residential lawn or managing large commercial properties, correctly installed trimmer line will give you clean, even cuts and reduce the risk of equipment damage. If you ever find yourself wondering how to put line in Stihl weed eater, refer back to this guide for a quick, reliable solution that will save you time and frustration.