If you’re using your chainsaw and suddenly notice an odor, whether it’s a smokey smell or gasoline, this is understandably a cause for concern. A smell from your chainsaw engine is typically a sign of something wrong.
Your chainsaw engine smells because of a dull chain, fuel mix with too much oil, leftover gasoline left in the tank from previous use, or your chainsaw might be flooded. Fixes include sharpening the blades, or changing or draining the oil.
In this article, I’ll discuss why a chainsaw engine may give off a noticeable smell. I’ll also explain how to rectify these problems so you can continue using your chainsaw safely and effectively.
1. Your Chain Is Dull
If you’re using an older chain that isn’t sharp enough to cut through wood effectively, it’ll take longer to get through a cutting job. This can cause the engine to overheat, giving off a smokey smell.
Even the best, highest-quality chains get old and worn with time, so it’s important to check your chainsaw regularly to ensure that the chain performs as it should.
How To Fix
If you notice that your chain is dull, you can sharpen the blades. To do this, you’ll need to use a chainsaw sharpening file that matches the size of your chainsaw’s teeth.
The following table outlines the most common chain pitches and the file they need (source):
| Chain Pitch | Size |
| 0.25 of an inch (0.635 cm) | 4 mm (0.16 in) |
| 0.325 of an inch (0.8255 cm) | 4.8 mm (0.19 in) |
| 0.404 of an inch (1.03 cm) | 5.5 mm (0.22 in) |
Alternatively, you can use an electric chainsaw sharpener instead of doing it manually. We recommend this Sharp Pebble Store Electric Chainsaw Sharpener Kit (link to Amazon). I like that this kit has everything you need, including a chainsaw angle guide attachment, a wrench, and a sharpening wheel. It’s also easy to use, even for novices. The adjustable speed settings allow for precise and quick sharpening.
Be sure to put on safety equipment before you sharpen a chainsaw chain. I recommend using work gloves and safety glasses. Always clean your chainsaw chain before sharpening it, and inspect it for broken teeth or severe damage. If the teeth are too damaged, it’ll be easier and safer to replace the chain entirely instead of attempting to sharpen it.
2. Your Fuel Mix Has Too Much Oil in It
A smoky smell from your chainsaw engine and visible black smoke from the machine indicate that your fuel mix might have too much oil. Check your chainsaw’s user manual to see the correct ratio for your machine.
Not only does the incorrect amount of oil in your fuel mix cause an odor, but it also means you’ll go through more fuel than necessary. There’s no reason to waste money or materials, so it’s best to address this situation sooner rather than later.
To learn more about this, check out my guide on properly fueling your chainsaw.
How To Fix
The solution is to replace the fuel with a more balanced mix. This involves emptying the old fuel and replacing it with one at the correct ratio. For optimal results, ensure that your fuel has a gas-to-oil ratio of 50 to 1. However, you may wish to check the user manual to see if the manufacturer recommends something more specific (source).
For the best results, I suggest using high-performance and low-smoke oil. You should make your fuel mix in a clean gas container.
For an eco-friendly oil, consder DEWALT Biodegradable Chainsaw Oil (link to Amazon). This oil is made from non-toxic, American-grown plant oils, so it is safer for the environment than petroleum-based oil. It also offers great lubricity, wear protection, and reduced high-speed oil sling.
3. There Was Leftover Gasoline in the Tank
If your chainsaw engine smells like gasoline, one potential cause is leftover gasoline left in the chainsaw’s tank from previous use. So, if you notice a gasoline smell after a long period of not using your chainsaw or the smell coming from a new chainsaw, this may be the cause.
If you just purchased a new chainsaw and notice a gasoline smell, you might be frustrated that something already appears awry with your new purchase. However, the gasoline may just be left behind from an engine test, so the gasoline smell doesn’t necessarily mean something is wrong with the chainsaw.
How To Fix
If there is leftover gasoline in the tank, this is usually not a problem or a reason to stress. You can add more fuel to the tank and use the chainsaw. If you’re concerned about the fuel’s quality, I recommend draining the tank and replacing the fuel before using the saw.
4. There’s Too Much Fuel in the Engine
A pungent gasoline smell can also indicate that the chainsaw is flooded, which means that there’s too much fuel in the engine, so it can’t ignite.
If too much fuel is in a chainsaw engine tank, there isn’t enough air to ignite the gas. Therefore, when you try to start the chainsaw, you’ll struggle, and it’s possible that the chainsaw won’t ever start.
How To Fix
Most of the time, you can let the chainsaw rest unused for a while. During this time, enough gasoline will evaporate that you’ll be able to start your chainsaw with no problems. However, sometimes the gasoline doesn’t evaporate quickly enough, and if you have an urgent job for which you need to use the chainsaw, this isn’t the most practical solution.
Follow these steps for an alternative way to start a flooded chainsaw:
- Engage the chain brake.
- Turn the choke off.
- Place a knee on the saw to hold it in place.
- Depress the throttle lever with one hand while pulling the starter rope with the other.
- The saw should start after approximately 15 pulls.
After using your chainsaw, check to ensure that you have the proper fuel mixture and that your spark plug is working properly.
Summary
Usually, a chainsaw engine smell signals something is wrong with the chain or fuel mix. A gasoline smell is likely due to leftover gasoline in the tank or too much fuel in the engine. Luckily, these problems are relatively easy fixes, and you should be able to return to using your chainsaw without the odor in no time.
