Smoking chainsaw = bad news.
Having equipment issues is one of the fastest ways to delay an otherwise good outdoor project. And one of the clearest indicators of a problem, is smoke. So here’s the question of the day and our summarized response:
Why is my chainsaw smoking?
Either your chain/bar is too hot, or there’s something wrong with your fuel. You can narrow down the possible causes quickly, by identifying if the smoke is coming from the chain/bar or from the engine.
Once you know the source of the smoke, it becomes much easier to fix.
Reasons a Chainsaw Will Smoke
There are several reasons a chainsaw might be smoking, but they all come down to two main categories: An overheating chain/bar, or fuel problems.
We’ll look at these one-by-one, but feel free to skip to the section that’s most relevant to your issue.
1. Chain/Bar is Too Hot
Friction is constantly present in the world of chainsaws. There is metal-on-metal friction between the chainsaw bar and the chain. There is metal-on-wood friction with every cut you make.
This friction can quickly create heat if not managed properly, and that heat can create smoke and even sparks or flames. Don’t freak out, because this is definitely NOT a normal part of the chainsaw’s operation.
There are several features built-into chainsaws that help prevent overheating on the bar/chain. Problems arise when they are not maintained properly, or when the unexpected happens.
Here are 3 examples of maintenance issues that can cause a chainsaw’s bar and chain to overheat:
- There is no (or not enough) bar oil
- The chain is too tight
- The chain is dull
For any of these causes, you’d be able to see the smoke rising from the bar or chain. If the smoke is actually coming from the engine, then your problem is with the fuel.
2. Issues with the Fuel
If your chainsaw is smoking from the engine, then your problem is more serious, and has potential to do greater damage to the machine.
The issue you’re facing is most likely being caused by contaminated, or improperly mixed fuel.
Chainsaw fuel is a mix of gasoline and oil. The exact ratio of the mixture can vary from one saw to the next. So it’s important that you always check the manufacturers manual to ensure you use the right mix of gas and oil.
A common point of confusion for new chainsaw users, is the difference between a chainsaw’s engine oil, and the lubricating bar oil. Let me boil it down for you: bar oil lubricates the chain, and engine oil gets burned as a part of the fuel mix.
Now here are the main problems that could make your fuel bad:
- Wrong mix of gas to oil
- Fuel contaminated with water
- Fuel contaminated with other substance (dirt, wood, etc.)
Running a chainsaw on bad fuel can cause long-term damage to the engine. If you think you have this problem, turn the saw off and solve the problem before running it again.
How to Fix Chain/Bar That’s Too Hot
If you have problem #1 (a hot bar/chain), then the solution is pretty straight-forward. Reduce heat!
More specifically, you’ll want to turn your chainsaw off, and let it cool down for awhile. Once the chain/bar is cool to the touch (don’t burn yourself!), then you can take the next few steps.
Fill-up your bar oil
First, check the bar oil. All chainsaws have a bar oil tank, and you can check the level by simply opening it up and taking a look.
You should never run a chainsaw without bar oil, which is essential for the tool to run properly.
Check your chain tension (e.g. tightness)
Second, check your chain tension. If you have your chain on too tight, then the bar-to-chain friction is going to be too intense even with enough bar oil.
We’ve actually done a really in-depth article that demonstrates how you can check your chain tension with two simple tests. You can find that article here.
Check and/or sharpen your chain
Next, check the chain. You can visually look for chips or damage to the chain, which is a sign that it needs sharpened or replaced. However, a chainsaw can still be dull even without any damage that is visually noticeable.
You can also tell if a chain is sharp, when it cuts without requiring you to apply pressure, or if the sawdust comes off in large flakes. A chain that requires you to push, or creates powdery sawdust, is dull and needs sharpened.
There are a number of ways you can sharpen your chainsaw. You can use a manual file, a grinder, or pay someone at a saw shop to do it for you.
If you’re willing to put a little time into learning the proper technique, then using a manual file can save you money and time in the long-run. Here’s a video that demonstrates our favorite manual file.
How to Fix Bad Fuel
To solve your bad fuel problem, dispose of the rest of the fuel in your chainsaw tank.
Then, inspect your fuel supply. Are there clear impurities? You may be able to tell if there’s water or dirt contaminating the fuel, just by looking at it.
If impurities are not visible, a likely issue is the ratio of your gas-to-oil mix. If you know the ratio you used, check your chainsaw manufacturers manual to see if they match.
If you don’t have a paper copy, it’s often really easy to find chainsaw user manuals online by googling “[chainsaw model name] users manual”.
Once you know the correct ratio, you may be able to adjust your fuel, by adding extra gas (or extra oil). If you’re not confident you can do this accurately, then it may be better to dispose of the fuel and start with a new batch.
Pro tip: mix your chainsaw gas in a small separate fuel can. This allows you to keep gasoline, and chainsaw fuel clearly separated. Plus, if you run into fuel issues, it’s easier to identify the root cause of the problem.
Things that Don’t Cause Smoke
Alright, now that we’ve covered the 2 groups of things that DO cause chainsaw smoke, I also wanted to mention some things that DO NOT cause chainsaw smoke.
In reading the comments on a few online forums, I’ve encountered some common misconceptions about chainsaw smoke, which I’m hoping to demystify.
Some of them seem plausible, but at the end of the day, none of the below are going to get you to the root cause of your chainsaw smoke.
1. Too much bar oil
If you have too much bar oil, then extra oil might spray off the chain. However, this also means your chain is super lubricated. If your chain is smoking, it’s not from too much bar oil.
2. Green wood (e.g. steam)
There’s a grain of truth to this one, because green wood can steam, which looks like smoke. But, this really only happens if your bar/chain are also too hot.
So in my mind, this goes back to overheating, and green wood is not an independent cause of chainsaw smoke.
3. Clogged air filter
This is a problem, yes. But it won’t cause your chainsaw to smoke, because it will kill your engine first. In other words, a clogged air filter is bad, but probably not the source of your smoke.
Wrap-up
Alright – there you have it. The 2 things to look at, when troubleshooting a smoking chainsaw.
If you have any further questions, feel free to give us a shout.
I hope you found this article helpful, and if you did, please share it with someone else who may benefit. We’re always happy to make new connections.
Alright, that’s all from me.
Now go do something awesome.
