Chain Saw Parts: Can't keep chain tensioned
If the chain on your chainsaw is coming loose, then check the knob, pins, gears, or the adjustor. Follow our repair and symptom guide to help you find the right part to install. Our repair information is a general guide to help you, but for more specific repair information related to your model, check your owner's manual.
Chains
If you run your chainsaw for an extended period of time, eventually the chain will stretch and will not keep the appropriate chain tension. It is recommended to check the chain tension every time you use your chainsaw. You are looking for slight give when you pull it, however the drive links should be engaged with the chainsaw bar. If not, you will need to tighten it by adjusting the tension screw. If your chainsaw will still not keep tension, you may need to replace your chain completely.
Gears
Some chainsaw models have a gear on the end of the adjustment screw that turns in order to adjust the saw's chain tension. Occasionally, these gears can become worn, and when this happens it is difficult to mesh with each other. If the gears won't mesh, you will not be able to adjust the tension on your chainsaw. If the gears are the problem, they can be relatively easily replaced, which usually solves the issue.
Knobs
Some chainsaw models have a quick tensioning system, which makes adjusting your chainsaw's chain tension much easier. It can also be known as a thumb knob adjuster, and it can be simply rotated to tighten the chain, rather than having to tighten a screw. However, the thumb knob is usually made of plastic, and over time it can wear and become damaged. When this happens, you will likely need to replace the thumb knob adjuster.
Pins
The adjusting pin moves back and forth as you turn the adjusting screw, which tightens and loosens the tension of the chain on the bar. If the adjusting screw becomes loose, the adjusting pin can occasionally fall out, making it impossible to adjust your chain tension. Unfortunately, because the pin is a small part, when it falls out you may not notice right away, and you can misplace the pin. This can happen over time, or if there is damage to either the pin or the screw. As you use the chainsaw, eventually the tension on the chain will loosen, so it is important to keep an eye on it and adjust as necessary. Otherwise the chain can jump off the bar during use, which is a very dangerous situation. ... Read more
Adjuster
The adjuster on your chainsaw is a small screw and pin system that allows you to tighten or loosen the tension of the chain. Without the proper tension, the chain may not stay on the bar properly, which not only makes it difficult to use your chainsaw, but also poses a safety risk. Over time, the screw of your adjuster can become loose or even fall out, and you can lose the adjuster pin. The threads on the adjusting screw can also become stripped, in which case the screw will need to be replaced. If you lose the adjuster pin, or it becomes damaged, it will need to be replaced. ... Read more