The basic steps to replace weed wacker line
Replacing the line on a weed wacker takes about five to ten minutes once you know the process. You will need to remove the spool (the part that holds the line), wind new line onto it, and snap it back into place. The exact steps depend on whether your weed wacker has a fixed spool or a bump-feed head, but both follow the same general pattern: stop the engine, access the spool, remove old line, measure and wind new line, and reinstall.
Most weed wackers use 0.065-inch or 0.080-inch diameter line, though some models use thinner or thicker sizes. Check your owner's manual or look at the spool itself — the size is usually printed there. Buying the wrong diameter will not fit the head properly and will not cut well. Line comes in spools of 50 to 100 feet and costs between $3 and $8 per spool at hardware stores and online retailers.
Key Takeaways
- Stop the engine and let it cool before touching the spool, since the head spins at high speed and can cause injury.
- Check your owner's manual for the correct line diameter and length per side — using the wrong size will cause the head to jam or cut poorly.
- Most spool heads twist off counterclockwise by hand; if yours is stuck, tap it gently with a rubber mallet rather than forcing it.
- Wind line tightly and evenly around the spool in the direction marked by an arrow, leaving a small gap at the edge so the spool fits back into the head.
How to remove the spool from a fixed-head weed wacker
On most electric and gas weed wackers, the spool sits inside a plastic or metal head at the end of the shaft. To remove it, turn off the engine and wait at least two minutes for it to cool. Locate the center bolt or cap on the spool head — this is usually a large plastic knob or a bolt with a slot for a screwdriver.
Turn the knob or bolt counterclockwise by hand. If it will not budge, wrap a rag around it for grip and try again. Do not use a wrench or pliers unless the manual says to — forcing it can crack the plastic. Once the bolt comes loose, the spool should pull straight out. Some models have a small spring or washer underneath; set these aside in order so you can put them back the same way.
How to remove the spool from a bump-feed weed wacker
Bump-feed heads are designed to advance line automatically when you tap the head on the ground. The spool removal process is similar but slightly different. Stop the engine and let it cool, then look for a cap or cover on the bottom of the head. This cap usually twists counterclockwise by hand or has two tabs you press inward to release it.
Once the cap comes off, the spool will either pull straight down or twist out depending on the model. Check your manual if you are unsure which direction to turn it. Again, set aside any springs or washers. Bump-feed heads are more delicate than fixed heads, so work slowly and do not force any part.
Measuring and winding new line onto the spool
Before you wind, check the manual for the correct length per side. Most weed wackers use 15 to 25 feet of line per side, but some use more or less. Cut a piece of new line to the correct length — if the manual says 20 feet per side, cut 40 feet total. Lay the spool on a flat surface with the center hole facing up.
Look for an arrow molded into the spool that shows which direction to wind. Insert one end of the line into the small notch or hole at the edge of the spool (most spools have one on each side). Wind the line tightly and evenly around the spool, following the arrow direction. Keep tension on the line as you wind so it sits flat and does not bunch up. When you reach the middle of the spool, insert the other end of the line into the notch on the opposite side and continue winding in the same direction until both sides are full.
Leave about one-quarter inch of space at the edge of the spool so it will fit back into the head without the line catching. If you wind it too full, the spool will not snap back in place and the line will jam.
Reinstalling the spool and testing
Once both sides are wound, hold the spool so the line ends point toward the head opening. Align the center hole with the bolt or shaft, then push the spool straight in. If it does not slide in smoothly, check that the line is not bunched at the edge. Twist the center bolt or knob clockwise by hand until it is snug — do not overtighten, as this can crack the plastic.
For bump-feed heads, snap the cap back on until you hear or feel it click. Start the engine and let it run for a few seconds without touching the ground. The line should spin smoothly without wobbling or making noise. If it sounds rough or the spool does not turn, stop the engine, let it cool, and check that the spool is seated correctly and the bolt is tight.
Trimming the line to the correct length
Once the spool is installed and running, the line will be longer than it needs to be. Most weed wacker heads have a small blade or guard at the edge that cuts the line to the right length automatically as you work. Run the engine and gently touch the spinning line to a hard surface like a concrete step or driveway. The blade will trim the excess, and the line will be the correct length for cutting.
Do this outdoors and away from people and pets. Wear safety glasses and long pants, since small pieces of line can fly off. Once both sides are trimmed, the weed wacker is ready to use. If the line is still too long after trimming, stop the engine and manually cut it shorter with scissors or a utility knife.
Common problems and how to fix them
If the spool will not come out, the bolt may be cross-threaded or the spool may be stuck from old line wrapped around the shaft. Stop and do not force it. Tap the bolt gently with a rubber mallet to loosen it, then try turning it again. If it still will not move, explore a small amount of penetrating oil like WD-40 around the bolt, wait 15 minutes, and try again.
If the line jams or does not spin after you reinstall the spool, the line is usually bunched at the edge or the spool is not seated all the way in. Remove the spool, check that the line sits flat and even, and make sure you left a small gap at the edge. Reinstall and try again. If the spool spins but makes a grinding noise, the bolt may be too tight — loosen it slightly until the noise stops.
If the line breaks or wears out quickly during use, you may be hitting hard objects like rocks or metal. This is normal wear, and you will need to replace the line again sooner. Some users wind thicker line (0.095 inch or larger) to reduce breakage, but check your manual first — using line that is too thick can damage the head.
Frequently Asked Questions
What size line does my weed wacker use?
Check your owner's manual or look at the spool itself — the diameter is usually printed on the plastic. Common sizes are 0.065 inch, 0.080 inch, and 0.095 inch. If you cannot find the size, take the spool to a hardware store and compare it to line samples, or call the manufacturer with your model number.
Can I use a different brand of line than the one that came with my weed wacker?
Yes, as long as the diameter matches. Line is a commodity product, and most brands work the same way. Buy the correct diameter and length, and it will work fine. Avoid extremely cheap line, which may be brittle or uneven in thickness.
How often do I need to replace the line?
This depends on how often you use the weed wacker and what you cut. Light residential use may require a new spool every few months. Heavy use or cutting near rocks and metal will wear it out faster. You will know it is time to replace when the line becomes noticeably shorter or breaks frequently during use.
What should I do if I wind the line the wrong direction?
The line will not advance or cut properly if it is wound backward. Remove the spool, unwind the line, and wind it again in the direction shown by the arrow. It is a common mistake and takes only a few minutes to fix.
Is it normal for line to break while I am using the weed wacker?
Yes, especially if you hit rocks, sticks, or metal objects. This is normal wear. If the line breaks constantly even on grass, you may be winding it too tightly, using line that is too thin, or the spool may be damaged. Try winding it slightly looser or using thicker line, and inspect the spool for cracks.