How to fix a chainsaw that’s overheating

Chainsaws are rugged tools built for heavy-duty work, but you definitely want them running cool. If your trusty chainsaw suddenly gets too hot to handle, it can be pretty alarming. Figuring out why it’s overheating and fixing it fast lets you get back to cutting with peace of mind.

The information in this article may not apply exactly to your specific appliance model. For the most accurate guidance, it’s best to check your manufacturer’s documentation or reach out to us if you have any questions.

Why your chainsaw is overheating

Overheating happens for various reasons. Since each chainsaw’s design is a bit different, start by checking the obvious stuff before digging deeper. Here are some common reasons why your chainsaw might be getting too hot:

• Not enough lubrication: Engine oil reduces friction between moving parts. Without enough oil, these parts rub together more, causing extra heat.
• Clogged cooling fins: Cooling fins help get rid of excess heat. If they’re covered in dirt and debris, your chainsaw’s engine might struggle to cool down.
• Dirty air filter: Airflow is crucial for combustion and cooling. A clogged filter restricts airflow, making the engine run hotter.
• Incorrect fuel mixture: A lean fuel mix (more air than fuel) creates extra heat inside the engine.
• Blocked spark arrestor or muffler: When these parts are clogged, exhaust gases build up, leading to overheating.
• Faulty ignition coil: A bad coil can cause irregular sparks, which strain the engine and cause it to overheat.

Safety precautions   

When working on any appliance, remember to keep safety first. Here are some tips to keep in mind: 

• If working indoors, make sure there is adequate ventilation to prevent the buildup of exhaust fumes. Carbon monoxide poisoning can be a serious risk.
• Wear insulated work gloves to protect your hands from sharp metal parts, pinching hazards and debris.
• Never attempt to service or repair while it is running or when the engine is still warm. Wait for all moving parts to come to a complete stop.
• Exercise extreme caution when working near blades, augers, or any other moving parts. Keep your hands, fingers, and clothing clear of these areas at all times.
• If the appliance has recently been used, give it plenty of time for any hot parts to cool down before working on it. 
• Empty the gas tank before beginning any work. Refill using fresh fuel. 
• Clean up oil spills right away to prevent slipping or other damage. 
• When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.
• Take your time and don’t rush while working to prevent accidents and personal injuries.
• Work in a well-lit area so you can clearly see and access the interior parts.
• Clear your workspace of clutter and other obstacles. Keep children and pets away from the work area.
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause injury.
• Wear safety glasses when working with chemicals, dust or cleaning large debris to prevent injury. 
• When not in use, store the machine in a safe and dry location.

Checking for proper lubrication

Lubrication plays a huge role in keeping your engine cool. If the chain and bar aren’t getting enough oil, friction goes up, and so does the heat. You might even see smoke or smell something burning if oil is low. Here’s what to do:

1. Check the oil level: Find the oil reservoir (usually near the trigger or on the side). Take off the cap and look inside. If it’s low, top it up to the recommended level.
2. Look over the oil feed system: Some chainsaws have an adjustable oil flow screw. Make sure it’s set to provide enough oil. If you’re not sure where it is, check your manual.
3. Clear any blockages: If sawdust or debris is blocking the oil port, use compressed air or a small brush to clean it out. Don’t forget to clean the bar groove too.
4. Test it out: Start the chainsaw and hold the tip near a piece of paper or wood. Give it a little gas. You should see a thin line of oil on the surface, that means the oil is flowing properly.

Checking chain tension

If your chain is too tight, it can create extra friction and make your chainsaw overheat. Keeping the chain at the right tension helps it cut efficiently and keeps the heat down.

1. Turn off the chainsaw: Make sure it’s off and cooled down before making any adjustments.
2. Check the chain tension: Gently pull the chain away from the bar. It should have a bit of slack but snap back into place when you let go.
3. Adjust if needed: If it’s too tight or too loose, loosen the bar nuts and turn the tensioning screw to get the right tension, follow your manufacturer’s guidelines.
4. Tighten the bar nuts: After adjusting, tighten the bar nuts firmly to keep the chain secure.
5. Test it out: Start the chainsaw and make sure the chain moves smoothly without too much friction.

Cleaning the cooling fins

Cooling fins guide airflow around the engine and cylinder, helping get rid of excess heat. Over time, debris, sawdust, and dirt can build up on these fins, making it harder for them to cool things down. Cleaning them is pretty simple.

1. Turn off and cool down: Make sure the chainsaw is off and cool enough to handle safely.
2. Remove the cover: Use a screwdriver or the right tool to take off the cylinder cover and expose the cooling fins.
3. Brush away debris: Gently use a small brush or compressed air to remove dirt, sawdust, and other debris from the fins. Be careful not to bend or damage them.
4. Tackle stubborn grime: If there’s sticky sap or residue, use a mild solvent on a cloth to wipe the fins carefully.
5. Reassemble and test: Once it’s all clean, put the cover back on and run the chainsaw. Keep an eye on the temperature to see if the overheating gets better.

Inspecting and replacing the air filter

Your chainsaw needs a steady air supply for proper combustion. A dirty or clogged air filter limits airflow, making the engine run inefficiently and hotter. Sometimes you can clean the filter, but other times you might need to replace it.

1. Find the air filter cover: It’s usually on the top or side of the chainsaw. Remove the screws or latch.
2. Take out the filter: Carefully remove it, watching out for any dirt that might fall inside.
3. Check for dirt and damage: If it’s just dusty, tap it against a solid surface or use compressed air to clean it. If it’s torn, clogged, or soaked with oil, it’s time for a new one.
4. Install the clean filter: Put the filter back in place, making sure it fits snugly. Replace the cover and secure it.
5. Test the chainsaw: Start it up to see if performance and temperature improve. You want the engine to breathe easy.

Checking fuel mixture and quality

Most chainsaws have a two-stroke engine that needs the right mix of fuel and oil. If you use too little oil or old, poor-quality fuel, the engine runs hotter. Wrong ratios or stale fuel can also harm the engine over time. Stick to the manufacturer’s recommended mixture ratios for your specific model.

1. Drain old fuel: If your chainsaw hasn’t been used in a while, empty the old fuel into an approved container.
2. Mix the proper ratio: Use a clean gas can and measure the oil carefully. Most chainsaws use a 50:1 or 40:1 ratio, but double-check your manual to avoid damage.
3. Mix thoroughly: Shake the container to mix the oil and fuel evenly.
4. Refill the chainsaw: Pour the fresh mix into the fuel tank and tighten the cap securely.
5. Run the engine: Start your chainsaw and listen for smoother operation. Less smoke and consistent power are good signs.

Examining the spark arrestor and muffler

Exhaust buildup can happen if the spark arrestor screen or muffler gets clogged with carbon or debris. When these parts are blocked, hot gases stay trapped, causing higher internal temperatures.

1. Remove the muffler cover: Unscrew or unlatch the cover. Locate the spark arrestor screen behind it.
2. Clean or replace the screen: If it’s clogged, gently brush off the carbon deposits. If it’s badly corroded or damaged, replace it.
3. Check the muffler: Look inside for soot buildup. Use a small wire brush or soft cloth to clean it out. Be careful not to damage any internal parts.
4. Reassemble: Put everything back together, making sure it’s sealed properly. Start the chainsaw to see if it cools down better.

Testing the ignition coil

A failing ignition coil can cause weak sparks, leading to incomplete combustion and extra heat. Testing the coil might be a bit advanced, but it’s doable with the right tools. If you’ve got a multimeter, you can check the coil’s resistance.

1. Disconnect the spark plug wire: Turn off the chainsaw and let it cool. Remove the spark plug boot to prevent accidental starts.
2. Access the ignition coil: It’s usually near the flywheel. Remove any covers if needed.
3. Use a multimeter: Set it to ohms (Ω). Place one probe on the coil’s primary terminal and the other on the spark plug wire terminal. Check your manual for the normal resistance range. If it’s too high or too low, the coil might be bad.
4. Reassemble everything: Put the coil back, replace covers, and reconnect the spark plug wire. Start the chainsaw to see if the overheating issue improves.

Keeping your chainsaw running cool

If you need any replacement parts for your appliances, you can enter your model number at AppliancePartsPros.com to locate and order them. Most orders arrive in just two business days, and we have tons of great information in our repair help section and YouTube videos to help you troubleshoot.

Stay connected with the latest DIY tips, tutorial videos, and repair guides by following us on Facebook, Instagram and Twitter. We love hearing about your repair stories and successes. If you need more help or want personalized guidance, feel free to reach out to us. Let us know how we can help you tackle your next project with confidence.