The spark plug is a critical component of your Stihl hedge trimmer's engine, responsible for igniting the fuel-air mixture to power the engine. Like most parts on your Stihl power equipment, your spark plug deals with wear and tear, and can become fouled or worn which leads to poor engine performance, or difficulty starting your trimmer. But don’t worry — replacing the spark plug on your Stihl hedge trimmer is an easy task with just a few steps that you can complete at home.

Tools and Materials Needed:

• Replacement spark plug compatible with your Stihl hedge trimmer model
• Socket wrench or spark plug wrench (if included with replacement spark plug)
• Gap gauge tool (if necessary)
• Clean cloth or rag

Preparation

Start by ensuring that your hedge trimmer is turned off and disconnected from any power source. This prevents accidental starts and ensures your safety throughout the process. Allow the engine to cool down completely before proceeding to avoid the risk of burns. Put on any necessary safety gear, such as gloves and safety goggles, to protect your hands and eyes from dirt and debris.

Locate the Spark Plug

The spark plug is typically located on the engine block of your hedge trimmer. It will have a thick wire (spark plug wire) connected to its terminal. Use a clean cloth or rag to wipe away any dirt or debris around the spark plug to prevent contaminants from falling into the combustion chamber when the plug is removed.

Remove the Spark Plug

Using a socket wrench or spark plug wrench (if provided with your replacement spark plug), carefully loosen and remove the spark plug from the engine block. Turn the wrench counterclockwise to loosen the spark plug, then carefully unscrew it by hand once it is loose. Be cautious not to damage the spark plug or the surrounding components during removal.

Inspect and Prepare the Replacement Spark Plug

Before installing the new spark plug, take a moment to inspect it for any damage or defects. Ensure that the electrode gap matches the specifications for your hedge trimmer model. Use a gap gauge tool to adjust the electrode gap if necessary, following the manufacturer's recommendations.

Install the New Spark Plug

Carefully thread the new spark plug into the spark plug hole by hand, ensuring that it is properly aligned and seated securely. Use the socket wrench or spark plug wrench to tighten the spark plug clockwise until it is snug, being careful not to over-tighten. Over-tightening can damage the threads or the spark plug itself.

Reconnect the Spark Plug Wire

Once the new spark plug is securely installed, reattach the spark plug wire to the terminal on the spark plug. Ensure that the connection is tight and secure to prevent any loss of electrical conductivity.

Final Checks

Before starting the engine, double-check that the spark plug is installed correctly and securely. Inspect the area around the spark plug for any loose tools or debris that may have fallen during the replacement process. Once everything is in order, you're ready to start your Stihl hedge trimmer and test the new spark plug.