How To Replace the Line on a String Trimmer

A string trimmer is a useful gasoline-powered, hand-held machine used for cutting grass and plants. Instead of a metal blade, this device utilizes a monofilament line or nylon strings attached to a trimmer head. Once all the string or line has been used up, you can either replace the spool or simply add more line.

  • Go to your local hardware store and inquire if they have monofilament in stock. Check the trimmer’s manual for the correct type and size of line to buy. If you no longer have the manual, bring a small sample of the string with you to the hardware store. Common diameters for gasoline-powered trimmers are .080, .095, .105 or .155 inch of monofilament line. For electric-powered trimmers, the typical sizes are .065 or .080 inch. Just ask the salesperson to find the correct string for you.
  • Remove any remaining strings in the spool. Shut off the string trimmer’s motor and then unplug it. Lay it on a flat surface then turn the line head so that it faces upwards. Secure the trimmer with one hand and twist off the cover counterclockwise using the other. Check if the cover is secured by a safety tab. If it is, push on these tabs until you hear a click then start unscrewing the cover.
  • Replace or restring the spool. Pull out your trimmer’s spool. If you opted to replace the entire spool, simply slot in the replacement and feed about six inches of string through the housing’s eyelets or starter holes. If you choose to reuse the spool, thread about an inch of the strand of your replacement line into the housing’s tab or molded loop. If the trimmer has two cutting lines, get about thirty feet of line and insert fifteen feet into the housing’s molded loop. Check the spool for an arrow. This will indicate which direction you should twist the replacement monofilament. Wrap the line around the spool in tidy straight rows. Stop winding once the spool is around three-fourths filled. If the trimmer uses double lines, wind both ends of the string in the same way.  
  • Feed half a foot’s length of monofilament into the trimmer’s housing. Fasten the monofilament to the notches found at the underside of your trimmer’s spool. Spray some lubricant on the refilled spool before slotting it into place. Make sure to align the cover with the housing’s tabs. Replace the cover and twist it clockwise until the lid is tightened securely. Check if you have installed the line properly by pressing on the center button and pulling at the line simultaneously. The line head should let out about an inch of monofilament string. If the string doesn’t come out, remove the spool and check if the spring has been wound correctly.

To get more mileage out of your trimmer, it is a good idea to clean the spark plug, muffler, and air filter of your string trimmer periodically. Just clean the spark plugs once in a while. Make sure to purchase the correct spark plugs once it is time to replace these. Use a screwdriver to scrape off the carbon residue. Don’t forget to clean out the soot from the exhaust port. To clean the spongy air filter, wipe the surface then oil it properly before putting it back into its chamber. 


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