String Trimmer Maintenance

Always practice safety when using, maintaining or repairing any power equipment. Before you perform any of the trimmer maintenance options below:

• For a gas string trimmer, turn the power button off, empty the gas tank and disconnect the spark plug wire.
• For a cordless string trimmer, turn the power button off and remove the battery.

Whether you’re using a gas or electric string trimmer, a common maintenance task is replacing its string. Do this every 20 to 30 hours or once the spool is brittle or empty. Here’s how:

• Remove the disk.
• Dispose of any string trimmer line left behind.
• Re-string the disk to replace trimmer line.

A clean string trimmer will work better and last longer. Once during the season:

• With a steel brush, regularly remove any buildup of grass or grime.
• Using a mix of water and dish soap, take a cloth and thoroughly clean the string trimmer head of any grease, dirt or debris.
• Every 90 days or so, remove the air filter cover. If the air filter itself is dirty, replace it.

Every 3 to 4 months, it’s a good idea to remove the spark plug. Depending on the level of dirt, you should clean or replace it.

• Empty the fuel tank, take off the spark plug boot and remove the spark plug using a socket wrench.
• If the spark plug is brown, pour 1/4-ounce of engine oil into the cylinder.
• Pull the starting cord several times to distribute the oil.
• If the spark plug is black, replace it. Thread the replacement spark plug into the cylinder head. Secure it in place using a socket wrench.

At the end of the season, always empty the fuel tank so its fuel lines and carburetor stay clean when not in use. Check and tighten all screws and nuts. If you have a gas string trimmer, change the oil:

• Let the engine run for a minute or two so the oil is slightly warm. This will make it easier to drain.
• Unscrew the oil plug and carefully drain the oil into a container.
• Once the oil has fully drained, refill the reservoir to its fill line only. Overfilling the tank can damage the internal parts.
• Screw the oil plug back into place and reconnect the spark plug.
• Properly dispose of waste oil. Consult your local hazardous waste center for details.

Tip: Consult the manufacturer owner’s manual for the type of oil and the amount recommended.

A grass trimmer head replacement is often needed after about 50 hours of use. This will depend on how often you trim and what you trim. A good rule of thumb is to perform a gas trimmer head replacement every 1-2 years. Check your owner’s manual for any specific instructions. Below are the basic steps:

• Start by securely locking the shaft using a lock pin or Allen key.
• Turn the old trimmer head clockwise to detach it.
• Install the new head by securing it with a counterclockwise turn.
• Double-check that the new head is tightly in place.
• Remove the locking tools.

At the end of the season, clean your trimmer thoroughly.

• Hose it down to remove any extra dirt and debris.
• Inspect the string and replace it if needed.
• It’s also best to oil the parts with a bit of lubricant to prevent rust and corrosion while it’s not in use.
• Store your string trimmer in an area that’s cool and dry. This will prevent any rust and corrosion.
• Since there are no cords to wrap, cordless string trimmers are generally easier to store. You can hang them vertically or horizontally.
• If kids or pets have access to the space, keep your trimmer higher off the ground and out of reach.