The Basic Steps to Load New String

Replacing the string on a weedeater takes about five to ten minutes once you know the process. Most weedeaters use one of two designs: a bump-feed head that advances string when you tap the head on the ground, or a manual-advance head where you turn a dial or knob to feed out fresh line. The steps differ slightly between them, but both start the same way: stop the engine, let it cool for a few minutes, and remove the spool from the head.

Before you begin, buy the correct string diameter for your model. Check your weedeater's manual or the label on the head itself—common sizes are 0.065 inch, 0.080 inch, and 0.095 inch. Using the wrong size can jam the head or break the string too often. You will also need a small screwdriver, usually Phillips head, to open the spool housing.

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 weedeater's manual or the label on the head to find the correct string diameter—using the wrong size will cause jams or breakage.
  • Most weedeaters have either a bump-feed head (taps the ground to advance string) or a manual-advance head (turn a dial to feed line), and each loads string differently.
  • Wind the string tightly and evenly around the spool in the direction marked by arrows on the head, leaving the correct length of free line at the end.
  • Test the head by tapping it gently on the ground or turning the dial before you start the engine to make sure the string feeds smoothly.

How to Remove the Old Spool

Locate the center bolt or knob on the top of the weedeater head. On most models, this is a single Phillips-head screw or a plastic knob that twists counterclockwise. Turn it slowly until the spool housing comes free—do not force it, as the spring underneath can pop out and get lost. Set the bolt and any washers in a small cup so you do not misplace them.

Lift the spool straight up and out of the head. You will see a small spring underneath; leave it in place unless it falls out on its own. If the spring does come loose, note which way it sits—the flat side usually faces down toward the head base. Pull out any remaining bits of old string from the spool and the head cavity. Wipe the inside of the head with a dry cloth to remove grass clippings and debris.

Loading String on a Bump-Feed Head

Bump-feed heads have two slots or eyelets on opposite sides of the spool where the string exits. Look for arrows printed on the spool that show which direction to wind. Cut a length of new string about 20 feet long—you can trim it later. Insert one end into one of the slots and hold it in place with your thumb while you wind.

Wind the string tightly and evenly around the spool in the direction the arrows point. Keep tension on the string as you wrap so the coils sit flat and do not overlap. Wind until you have about 6 to 8 inches of string left free. Tuck the free end into the slot on the opposite side of the spool, then thread both free ends through the eyelets on the head itself. Reinstall the spool into the head, replace the spring if it came out, and screw the center bolt back in hand-tight—do not over-tighten.

Loading String on a Manual-Advance Head

Manual-advance heads have a single spool with a dial or knob around the edge. These heads usually have a small hole or notch where you insert the string end. Cut a length of new string about 20 feet long. Insert one end into the hole and hold it firmly while you begin winding.

Wind the string around the spool in the direction marked by arrows, keeping it tight and flat. Wind until you have about 6 to 8 inches of free line remaining. Thread the free end through the eyelet on the head, then reinstall the spool and tighten the center bolt by hand. With manual-advance heads, you will turn the dial clockwise (or in the direction shown on your head) to feed out new string as the old line wears down.

Trimming and Testing the String

Once the spool is back in place, you need to trim the string to the correct length. Most weedeaters cut string to length automatically when you start the engine—the spinning head will hit a guard or blade and snap off the excess. However, you can trim it by hand first to avoid waste. The correct length is usually 8 to 10 inches on each side of the head, though your manual may specify a different length.

Before you start the engine, test the head by hand. If you have a bump-feed head, tap it gently on the ground a few times—you should see a small amount of string feed out. If you have a manual-advance head, turn the dial slowly and watch the string advance. If nothing happens, the string may not be seated correctly in the slot. Stop, remove the spool again, and check that the string end is fully inserted and held in place.

Common Mistakes to Avoid

The most frequent error is winding the string in the wrong direction. Always check the arrows on the spool before you start—winding backward will cause the string to unwind when the head spins. Another common mistake is winding too loosely or leaving gaps between coils. Loose string will tangle inside the head and jam, stopping the feed. Wind firmly and keep each loop tight against the previous one.

Do not overfill the spool. If you wind too much string onto it, the spool will not fit back into the head, or the string will jam when it tries to advance. Aim for about 6 to 8 inches of free line at the end—that is usually the right amount. Finally, do not over-tighten the center bolt when you reinstall the spool. Hand-tight is sufficient; over-tightening can crack the plastic housing or strip the threads.

When to Replace the Entire Head

If the spool is cracked, the eyelets are broken, or the spring is missing or damaged, you may need to replace the entire head rather than just the string. Heads typically cost between fifteen and forty dollars depending on your weedeater model. Check your manual for the correct replacement head, or bring your weedeater to a hardware store or small-engine repair shop and ask them to identify the right part.

Some weedeaters have sealed heads that do not open—these are designed to be replaced as a unit when the string runs out. If your head has no visible screws or seams, it is likely a sealed type. In that case, unscrew the entire head from the shaft and thread on a new one, making sure it is tight before you start the engine.

Frequently Asked Questions

How much string should I load onto the spool?

Load until you have about 6 to 8 inches of free line left at the end. If you wind too much, the spool will not fit back into the head or the string will jam. If you wind too little, you will run out of string too quickly and have to reload again soon.

What happens if I wind the string in the wrong direction?

The string will unwind as the head spins, and you will lose all your line within seconds. Always check the arrows printed on the spool before you start winding. If you wind it backward, straightforward remove the spool and rewind it in the correct direction.

Can I use a different string diameter than what my manual says?

No. Using the wrong diameter can jam the head, break the string too often, or damage the feed mechanism. Always match the size listed on your weedeater's label or in the manual. Common sizes are 0.065, 0.080, and 0.095 inch.

Why does my string keep breaking or jamming?

The most common causes are winding the string too loosely, winding it in the wrong direction, or using the wrong diameter. Check that each coil is tight and flat against the previous one, and verify the direction with the arrows on the spool. If the string still jams, the spool or eyelets may be cracked and need replacement.

Do I have to trim the string by hand, or will the weedeater do it automatically?

Most weedeaters trim the string automatically when you start the engine—the spinning head hits a guard or blade and cuts off the excess. You can trim it by hand first to save string, but it is not necessary. The correct final length is usually 8 to 10 inches on each side of the head.