Direct Answer: How to Replace Weed Eater String
To replace string on a weed eater, first disconnect the power by unplugging electric models or removing the spark plug on gas-powered trimmers. Locate and identify your trimmer head type (bump-feed, manual-feed, or fixed-spool), then remove the spool or head cover. Extract the old string, wind new nylon string onto the spool following the directional arrows, and reassemble the head. The exact procedure varies by head style, so identifying your trimmer’s mechanism before starting is essential.
Identify Your Trimmer Head Type
Before attempting any string replacement, you need to determine which type of trimmer head your weed eater has. This identification step is critical because each head design uses a different string replacement procedure.
Bump-Feed Trimmer Heads are the most common type found on modern weed eaters. These heads automatically advance string when you tap or “bump” the head against the ground during operation. The spool sits inside a semi-transparent plastic cover, and you’ll see a center knob that either twists off or unscrews. Bump-feed heads are typically found on electric trimmers and mid-range gas models.
Manual-Feed Trimmer Heads require you to manually pull string from the spool and cut it to length before feeding it through the trimmer head. These heads lack the automatic advancement feature and are common on professional or commercial-grade equipment. You’ll notice they have a more open design without the bump cover.
Fixed-Spool Heads use pre-wound spools that cannot be reloaded. Instead of winding string yourself, you replace the entire spool with a pre-wound replacement. These are often found on cordless electric trimmers and some commercial models. The spool itself is disposable, making maintenance straightforward but more costly over time.
To identify your specific head type, examine your trimmer head closely. If it has a bump knob and a removable center knob, you likely have a bump-feed head. If the design is more open with visible string guides, you probably have a manual-feed head. If the entire spool is sealed and disposable, you have a fixed-spool design.
Safety Preparation Before Starting
Always prioritize safety when working with trimmer equipment. These precautions prevent accidental injuries and protect both you and your equipment.
For Electric Trimmers: Unplug the device from the electrical outlet and wait at least two minutes before beginning work. This ensures the motor has completely stopped and any residual charge has dissipated. Some electric trimmers have safety switches that prevent accidental activation, but unplugging provides complete protection.
For Gas-Powered Trimmers: Locate the spark plug wire and remove it from the spark plug. This prevents the engine from accidentally starting while you’re working with the trimmer head. Allow the engine to cool for at least 10 minutes if the trimmer was recently used, as the engine and trimmer head can reach high temperatures.
Work Area and Attire: Perform string replacement on a clean, flat work surface. Wear safety glasses to protect your eyes from debris or spring components that may release during disassembly. Have a small container nearby to hold fasteners and small parts so they don’t get lost. Keep the trimmer stable during work by placing it on a bench or securing it in a vise.
Remove the Trimmer Head or Access the Spool
Accessing the spool is straightforward but varies depending on your trimmer head type. Most weed eaters allow you to access the spool without removing the entire head from the trimmer shaft.
For Bump-Feed Heads: Locate the center knob at the top of the trimmer head. Most bump-feed designs use either a twist-off knob or a push-and-twist mechanism. Turn the knob counterclockwise to loosen it; some models require you to press and twist simultaneously. Once loosened, the knob will separate, exposing the spool. The spool itself typically lifts straight out once the knob is removed. Take note of the spool orientation before removal so you can reinstall it correctly.
For Manual-Feed Heads: These heads usually have a removable cover or housing. Look for fasteners such as screws or clips holding the cover in place. Using an appropriate screwdriver or Allen wrench, remove these fasteners and carefully separate the cover. The string guides and feed mechanism will become visible once the cover is removed. Some manual-feed heads have a retaining ring that twists off instead of fasteners.
For Fixed-Spool Heads: These typically have a removable cover or cartridge. Look for a release button or lever on the side of the head. Pressing or pulling this release allows the spool cartridge to slide out or pop free. Some fixed-spool designs require the entire head assembly to be unscrewed from the trimmer shaft, but most allow spool replacement without full removal.
If you encounter fasteners, use an appropriately sized tool to avoid stripping screw heads or damaging plastic components. Place all removed fasteners in a small container to prevent loss.
Extract Old String and Prepare for New String
Removing old string can be challenging, especially if it’s tangled, broken, or wound too tightly. Take your time with this step to avoid damaging the spool.
Removing Old String: If the string is still intact, grasp both strands at the spool and pull them out slowly. Some string may resist removal if wound tightly; apply steady, even pressure rather than jerking the string. If the string is broken into pieces, use needle-nose pliers to extract fragments from the spool grooves. Work patiently, as forcing removal can crack plastic spools.
Cleaning the Spool: Once old string is removed, use a dry brush or cloth to clear any debris, dust, or remnants from the spool grooves. This ensures the new string winds smoothly and helps the spool operate properly. If the spool has visible damage, cracks, or worn grooves, replacement may be necessary for optimal performance.
Selecting Replacement String: Weed eater string comes in various diameters, typically ranging from 0.065 inches to 0.105 inches. Check your trimmer’s manual or the equipment specification label to determine the correct diameter for your model. Using the wrong diameter can prevent proper feeding or reduce cutting efficiency. Purchase replacement string that is clearly labeled as compatible with your trimmer model. Nylon string is the standard material and works with virtually all residential and commercial weed eaters.
Pre-wound replacement spools are also available for many popular trimmer models, eliminating the need to wind string yourself. These options are convenient, though they typically cost more per replacement than bulk string.
Wind New String Onto the Spool (Bump-Feed Head)
Winding string correctly is essential for proper feeding and trimmer performance. Most bump-feed spools have directional arrows indicating the correct winding direction.
Prepare the String: Measure approximately 20-25 feet of new string, depending on your trimmer model. Most residential weed eaters require 15-20 feet per spool, but checking your manual ensures accuracy. Cut the string cleanly with a utility knife for easier winding.
Locate the String Anchor: Examine the spool and identify the small notch or anchor point where the string begins. This is typically located at the outer edge of the spool. Insert one end of the string into this anchor, ensuring it’s seated firmly.
Wind in the Correct Direction: Follow the directional arrows printed on the spool. These arrows indicate the rotation direction for proper string advancement. Turn the spool in the indicated direction, winding the string tightly and evenly across the spool grooves. Avoid overlapping or crossing string, as this causes tangling and feed problems. The string should lie flat in neat, parallel rows.
Load the Correct Length: Wind string until approximately 12-18 inches remain unwound. This remaining length will be the cutting string exposed through the trimmer head. Leave the string loose in this section; don’t wind it onto the spool. Some bump-feed designs have marked positions indicating how much string to load.
Secure the Loose End: Most bump-feed spools have a small notch or slot on the outer edge where you insert the loose string end to hold it in place during reassembly. Insert the remaining string into this notch, ensuring it’s secure but accessible for threading through the head openings.
String Replacement for Manual-Feed and Fixed-Spool Heads
Alternative trimmer head designs require different string replacement procedures.
Manual-Feed Trimmer Heads: These heads require you to load two separate string lengths rather than winding one continuous strand. Measure two pieces of string, typically 12-15 feet each depending on head design. Thread each piece through the designated feed guides in the trimmer head, ensuring they exit through the cutting ports equally. The head design positions these strings so they feed outward for cutting. Secure each string end in the head’s retention slots or notches. Manual-feed systems give you complete control over string length and replacement timing, though they require more frequent maintenance than bump-feed designs.
Fixed-Spool Heads: These require no winding or installation. Simply remove the old spool cartridge and insert a new pre-wound spool, ensuring it’s oriented correctly and fully seated. Most fixed-spool designs include alignment tabs that prevent incorrect installation. Once the new spool is seated, reinstall any covers or cartridge holders and test the head’s operation. This design offers the simplest replacement process but limits your ability to customize string length or type.
Reassemble and Test Your Trimmer
Careful reassembly ensures your trimmer operates safely and cuts effectively.
Reinstall the Spool: Place the wound spool back into the trimmer head, ensuring it’s oriented correctly and seated fully. The spool should sit flush within the head housing. For bump-feed heads, check that the string passes through the feed holes or guides and that the loose end is properly positioned in the retention notch.
Reattach the Center Knob: For bump-feed designs, thread the center knob back onto the spool shaft and turn clockwise until snug. Don’t overtighten, as excessive force can crack plastic components. The knob should be tight enough to hold the spool securely but not so tight that future removal becomes difficult.
Reinstall Fasteners: For manual-feed or other head designs, reattach any screws, clips, or fasteners you removed. Use moderate pressure to avoid cross-threading or stripping. Verify that all fasteners are secure before testing.
Pre-Operation Checks: Before operating the trimmer, visually inspect the head to confirm the string is properly positioned and the head assembly is fully reassembled. Gently rotate the trimmer head by hand to verify there’s no resistance or catching. For bump-feed heads, the spool should rotate freely inside the head housing.
Outdoor Test: Start the trimmer and allow it to run at low speed for 10-15 seconds in an open area, away from people or property. Listen for any unusual sounds and watch for proper string rotation. The string should extend outward and rotate smoothly. Gradually increase engine speed and verify that the string advances if you have a bump-feed head. Stop the trimmer immediately if you notice vibration, noise, or abnormal operation.
Troubleshooting Common String Replacement Issues
String Won’t Feed or Advance: If string doesn’t advance from the spool, the issue is typically improper winding direction. Stop the trimmer, allow it to cool, and remove the spool to verify you wound the string in the direction indicated by the spool arrows. Winding in the wrong direction prevents the bump mechanism from advancing string. Additionally, check that the string passes through all feed holes and isn’t caught on the head housing.
String Breaks Repeatedly: Continuous string breakage usually indicates the string is winding too tightly on the spool, creating excessive tension during feeding. When rewinding, apply moderate, even pressure rather than pulling tightly. Ensure the string lies flat without overlapping or twisting. Also verify you’re using the correct string diameter for your trimmer model, as undersized string can’t withstand cutting forces.
String Wound Too Tightly or Loosely: Overly tight winding stresses the string and causes breakage; loose winding prevents proper feed. When rewinding, maintain consistent, moderate tension that allows the string to sit flat in spool grooves without bulging. The completed wind should feel firm but not rigid.
String Tangled Inside Head: If string becomes tangled after reassembly, remove the spool and carefully separate the tangled portions. This usually occurs when string overlaps during winding or when the loose end isn’t properly secured in the retention notch. Rewind more carefully, ensuring each layer sits flat and separate.
Uneven String Length or Exposed String Cutting Unevenly: This occurs when the two strings extending from the trimmer head aren’t the same length. Remove the head cover and verify both strings are equally exposed through the cutting ports. If one string is shorter, you likely wound it too short on the spool or didn’t load enough total string. Rewind with additional string length to balance the cutting edges.
Frequently Asked Questions
How often should I replace my weed eater string?
String replacement frequency depends on usage intensity. Occasional homeowners may replace string 1-2 times per season, while regular users might need monthly replacements. You’ll know it’s time when string becomes noticeably worn, frayed, shorter than usual, or breaks frequently during operation. Most users notice declining cutting efficiency as the first sign that string replacement is due.
Can I use any diameter string on my trimmer?
No, you should always use the diameter specified by your trimmer’s manufacturer. Using oversized string strains the motor and feed mechanism, while undersized string breaks under normal cutting loads. Your trimmer’s manual or the specification plate on the equipment lists the correct diameter, typically ranging from 0.065 to 0.105 inches.
What’s the best way to store unused trimmer string?
Store bulk trimmer string in a cool, dry location away from direct sunlight and extreme temperatures. Keep it sealed in its original packaging or in an airtight container to prevent moisture absorption, which can degrade nylon string. Properly stored string remains usable for several years.
Do I need special tools to replace weed eater string?
Most string replacements require only basic hand tools: a screwdriver (Phillips and flathead), possibly an Allen wrench, and needle-nose pliers for removing stubborn string fragments. Your trimmer’s manual specifies any specialized tools needed for your particular model. Most residential string replacements need no tools beyond what’s in a standard toolbox.
