How to Remove Spark Plug from a Stihl Chainsaw
Learn a safe, step-by-step method to remove and inspect a spark plug on your Stihl chainsaw. This guide covers the right tools, safety practices, and troubleshooting to keep your saw starting reliably.
By safely removing the spark plug from a Stihl chainsaw: ensure the engine is cool, disconnect the spark plug boot, remove the air filter cover, use a proper spark plug wrench to loosen the plug, and inspect it before reinstalling with the correct gap. Always wear PPE and work on a stable surface.
Safety and Preparation
Safety always comes first when working on powerful tools like a Stihl chainsaw. Before you touch any internal parts, make sure the engine is completely cool and the saw is on a stable, non-slip surface. Engage the chain brake and disconnect the spark plug boot to prevent accidental spark and electric shock. According to Chainsaw Manual, safe spark plug work begins with cooling, using the correct tools, and keeping your hands away from hot metal and moving parts. Wear PPE including gloves, safety glasses, and hearing protection. Keep a clean work area to avoid dirt falling into the carburetor or the air intake, which can cause performance issues later.
- Ensure the saw is off and cool before starting.
- Engage chain brake and secure the unit on a stable surface.
- Wear appropriate PPE to protect hands, eyes, and ears.
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Tools & Materials
- Spark plug wrench (13/16")(Choose a plug socket that fits the model’s plug size; many Stihl models use a standard 13/16" spark plug wrench.)
- Screwdrivers or nut driver(Needed to remove the air filter cover screws.)
- Replacement spark plug(Select the exact type recommended for your Stihl model and a new gap if swapping plugs.)
- Air filter (optional)(Inspect or replace if dirty or oily.)
- Clean rag(Use to wipe dust and clean the area around the plug well.)
- Spark plug gap gauge(Check and adjust the gap to the manufacturer’s spec.)
- Gloves(Protect hands from sharp parts and hot surfaces.)
- Torque wrench (optional)(Use if your model requires a precise torque on the plug.)
Steps
Estimated time: 25-40 minutes
- 1
Power off and cool down
Ensure the saw is switched off, the chain brake is engaged, and the engine is completely cool before touching any internal parts. Do not attempt removal while the engine is hot, as this can cause burns and damage to the plug threads.
Tip: Never touch hot engine parts; wait at least 5 minutes after turning the engine off. - 2
Disconnect the spark plug boot
Firmly grip the boot and pull straight away from the spark plug. Do not twist; twisting can damage the boot lead or the spark plug seat.
Tip: If the boot sticks, gently wiggle while pulling to avoid tearing the lead. - 3
Remove the air filter cover
Use the appropriate screwdriver to remove the screws holding the air filter cover. Place screws in a container so they don’t get lost and set the cover aside.
Tip: Support the cover so the clips don’t snap or break when removing the filter. - 4
Remove the air filter and expose the plug
Take out the air filter and inspect the housing area. This exposes the spark plug so you can access it with the wrench.
Tip: Be careful not to drop debris into the intake while removing the filter. - 5
Loosen and remove the spark plug
Fit the spark plug wrench onto the plug and turn counterclockwise to loosen. Once loose, lift straight up to remove from the threads.
Tip: Grip the plug body, not the ceramic tip, to prevent damage. - 6
Inspect the spark plug
Check for fouling, glazing, or wear. If the electrodes are worn or heavily fouled, replace the plug rather than attempting to clean. A worn plug can cause starting issues and rough idling.
Tip: Note any oil, fuel, or carbon buildup and address root causes if found. - 7
Check gap and reinstall
If reusing, check the gap with a gauge and adjust per manual specifications before installation. Thread the plug by hand to avoid cross-threading, then snug it securely using the wrench.
Tip: Always start threading with your hand to prevent cross-threading. - 8
Reconnect and test the saw
Reconnect the boot, replace the air filter, reassemble the cover, and start the engine at a low idle to verify operation. If starting is difficult, re-check seating and gap of the plug.
Tip: If the engine runs rough, re-check the plug seating and the air intake for blockages.
FAQ
Do I need to remove the spark plug wire before attempting removal?
Yes. Disconnect the spark plug boot before touching or removing the plug to avoid shock or arcing.
Yes. Always unplug the spark plug boot before handling the plug to avoid shocks.
What should I do if the plug is fouled with oil or carbon?
A fouled or oily plug should be replaced with a new one rather than cleaned, as cleaning can leave residue that affects performance.
If it’s fouled, replace it rather than trying to clean it.
How can I tell if the spark plug is worn?
Look for worn electrodes, glazing, or rounded edges. If unsure, replace with a plug that matches your model’s spec.
Worn electrodes or heavy buildup means replace the plug.
Can I reuse the plug after cleaning?
Reusing a cleaned plug is not recommended if there is wear or fouling; replace with a new one for best results.
Better to replace than reuse a worn plug.
Where can I find the correct gap specification?
Check the chainsaw manual or plug packaging for the correct gap; set the gap with a gauge before reinstalling.
See the manual or packaging for the correct gap.
Watch Video
The Essentials
- Power off and cool before handling spark plugs
- Use proper tools to avoid damaging threads
- Inspect and replace worn plugs rather than cleaning
- Verify correct gap per manual before reinstalling
