This is another common questions from new chainsaw users. Unfortunately, they mostly ask this after it has already happened.
Do chainsaws overheat? Yes, chainsaws can overheat but it shouldn’t happen under normal conditions. If the engine is running too hard or if it doesn’t get sufficient ventilation or lubrication it can quickly overheat, which can lead to malfunction.
There are a number of reasons to why it can happen, but all of them can be prevented with regular maintenance and being cautious. Let’s look into it!
Why do chainsaws overheat?
Here are the most common reasons for an overheating chainsaw. Sometimes it’s caused by only one of them, but in many cases it’s a combination of two or more so always make sure that everything is in order before using your chainsaw.
Insufficient oil in fuel mixture
This is perhaps the most common reason out of all of them. Chainsaws use 2-stroke engines (unless it’s an electric chainsaw). These engines need a mix of oil and fuel to run properly (more on this later). This is because the oil mixed into the fuel serves as a lubricant for the pistons inside the engine.
Without this, the pistons will start grinding on the insides of the engine, generating a lot of heat in the process that will inevitably ruin the engine itself.
This can happen to new chainsaw users who simply didn’t know better (and did not read the user manual) but also to veterans who just grabbed the wrong can of fuel by accident.
Either way, this is probably the fastest way to overheat and ruin a chainsaw, as it usually happens within 10 minutes of starting it up. You usually can’t detect that something is wrong either, until the chainsaw stops working.
The chain isn’t sharp enough
If your chain isn’t sharp enough, your chainsaw needs a lot more power to cut trees than it normally would under optimal conditions. Depending on how dull the chain is, this can even cause the chainsaw to overheat due to the huge amount of force it needs to put out all the time.
This in itself usually isn’t enough to cause damage to the chainsaw, but in combination with something else such as a clogged air filter it can do some real damage over time.
Fortunately, this one is easy to notice. If your chain isn’t biting into wood as it should, or if it takes longer to cut through wood than usual, it’s time to resharpen your chain.
Covered or clogged exhaust port
Much like a car, a chainsaw also has an exhaust port where the fumes generated by the engine can exit the device. You usually don’t need to pay much attention to it, but if it gets clogged up by something, it can cause some serious problems.
This is mostly because fumes leaving the exhaust port are warm, and if they can’t leave the chainsaw properly a good part of the chainsaw’s ability to give off heat into the surrounding air will suffer, causing it to become more hot than it normally would be.
Fortunately, this rarely happens. It’s usually the result of storing the chainsaw in an unsuitable place where various debris can get stuck in it. Also, it’s easy to notice if you use your chainsaw often because it will sound a bit differently if the exhaust port is clogged.
Clogged up air filter
Unlike the exhaust port problem, this will eventually happen to every chainsaw that uses fuel.
The engine itself needs air to operate. To prevent dust from getting into the engine, chainsaws have an air filter installed. While the engine is running, a lot of air passes through this filter and over time it can accumulate a lot of dust. Eventually it can get to the point where clean air can no longer pass through.
When this happens, the engine will simply stop because it can’t operate without air. But until it finally stops, it will get more and more hot in there due to the lack of fresh air.
This is especially common when you use your chainsaw in the rain, or shortly after. When moisture gets into the air filter – either due to moist air or some raindrops falling in it directly – it will mix with the dust on the air filter.
The resulting gray mixture can stop air from passing through really fast, so always clean your air filter before using your chainsaw in a moist environment.
Cutting a tree that is too big
People sometimes try to cut down a tree that is too big for their chainsaw. What usually happens is that the guide bar gets stuck in the tree and they keep running the engine while trying to force the bar out of the tree somehow.
This is bad practice, and can damage your chainsaw. Trying to rotate the chain while a huge piece of wood is essentially holding it in place is a very bad idea. It can cause the engine to overheat and bend your guide bar in the process, among other things.
If your chainsaw ever gets stuck in a tree you should use a felling wedge to get it out. If you aren’t sure what these are, or just want to learn more about cutting large trees with a small chainsaw, check out this article I wrote on the topic.
How to tell if a chainsaw has been overheated?
Most of the signs are rather obvious. First, the chainsaw can feel more warm than usual, sometimes to the point where it gets really hot.
Another sign to look out for is the sound that the chainsaw gives off while operating. If it’s different than usual, or maybe even changes to a lower tone while running, you my want to check if everything is in order.
A drop in performance also implies that something is wrong. The drop can be sudden but sometimes it happens gradually so pay close attention.
And finally, the chainsaw giving off smoke is a surefire sign of it being overheated. I’m not talking about exhaust smoke, but smoke with “unnatural” color and intensity.
And finally, if your chainsaw stops after displaying one or more of the above signs – you can be about 90% sure that it overheated.
How to prevent a chainsaw from overheating?
As I’ve said before, overheating can be prevented with regular maintenance and paying attention. Here are some tips to keep in mind:
Clean your air filter regularly
The air filter of a chainsaw is usually placed in some easy to access location, most commonly around the top of the engine. Check your user manual for it’s exact location and the way to get to it, as it can be slightly different for every manufacturer.
Once you have the air filter in your hand, rinse it with running water until you can no longer see any dust on it. After you are done, let it dry then put it back to its place and you are ready to go.
Make sure to use the proper oil/fuel ratio
Most chainsaws use the 1:50 oil/fuel ratio, but always check your user manual for the ratio recommended by the manufacturer. If you don’t use your chainsaw all that often, you can buy pre-mixed fuel, just to be sure.
To prevent any “accidents” with unmixed fuel from happening, I suggest buying a can with a different color for your chainsaw fuel. Alternatively, you can put stickers on your can or simply write “mixed fuel” on it in a way that it’s impossible to miss.
Sharpen your chain regularly
You should always check if your chain is in good condition before starting to work. I personally like to do some practice cuts on firewood before I start doing anything serious.
If your chain is dull, you should sharpen it before using your chainsaw. Or if it’s in really bad condition, you should consider buying a new one.
Make sure that the exhaust port isn’t clogged
This one is pretty easy, just check it every time before you start up your chainsaw. Again, this rarely happens unless you store your chainsaw on the ground in a barn or something. But better safe than sorry!
Can an overheated chainsaw be fixed?
It really depends on how much damage it suffered due to overheating.
If it no longer starts, then more than likely you have burned a piston. And replacing the entire engine block, while can be done, will likely cost more than buying a new chainsaw.
If you can start it up after fixing the conditions that caused it to overheat and there isn’t a noticeable drop in performance, you an probably keep using it.