How to stop a chainsaw chain from coming off a guide bar

Question

Accepted Answer

If your Husqvarna chainsaw keeps coming off the guide bar, it is usually caused by incorrect chain tension, a worn guide bar, damaged drive components or improper installation.

A chain that repeatedly comes off should be inspected immediately, as it can affect both safety and cutting performance.

This guide explains the most common causes and how to prevent the chain from coming off again.

Quick answer

If your chainsaw chain keeps coming off the guide bar, check:

Chain tension
Guide bar wear or damage
Chain condition
Drive sprocket wear
Correct chain installation
Make sure the clutch cover is installed correctly, and the bar nuts are tightened

In many cases, adjusting the chain tension correctly resolves the problem.

Is the chain tension correct?

A loose chain is the most common reason a chainsaw chain comes off the guide bar.

Signs the chain is too loose

The chain sags underneath the guide bar
The chain can be pulled far away from the guide bar
The chain frequently jumps during operation which can lead to damaged drive links

Check the tension

The chain should sit snugly against the guide bar
It should still move freely by hand when wearing gloves
It should snap back into place when pulled gently

Check chain tension regularly, especially when using a new chain, as chains naturally stretch during the first hours of use.

How to tension a chainsaw chain

Is the guide bar worn or damaged?

A worn guide bar may no longer hold the chain correctly.

Inspect the guide bar for:

Uneven rail wear
Bent rails
Excessive groove wear
Burrs along the rail edges

A damaged guide bar can allow the chain to derail during operation.

Is the chain worn or damaged?

Chains wear over time and may eventually no longer fit the guide bar correctly.

Inspect the chain for:

Damaged drive links and tie strap
Excessive wear
Bent or cracked components
Missing parts

Replace the chain if damage is found.

How to check, maintain and clean the guide bar

Is the drive sprocket worn?

The drive sprocket helps guide the chain around the chainsaw.

A worn sprocket can:

Cause poor chain alignment
Increase chain and bar groove wear
Contribute to the chain coming off the guide bar

Inspect the sprocket whenever replacing the chain.

Was the chain installed correctly?

An incorrectly installed chain may come off shortly after use.

Check that:

The drive links sit correctly in the guide bar groove
The chain is installed in the correct direction
The guide bar and clutch cover are properly secured
The chain tension is adjusted after installation

Even a correctly sized chain can come off if it is not installed properly.

How to assemble a chainsaw bar and chain

Common reasons a chainsaw chain comes off

The most common causes include:

Loose chain tension
Worn guide bar rails
Damaged chain drive links
Worn drive sprocket
Incorrect chain installation
Excessive guide bar wear

Identifying the root cause helps prevent the issue from recurring.

How to prevent the chain from coming off

To reduce the risk of chain derailment:

Check chain tension before each use
Inspect the guide bar regularly
Replace worn chains and sprockets
Maintain proper chain lubrication
Ensure the chain is installed correctly
Clean the guide bar groove during routine maintenance

Regular maintenance helps improve safety and extend component life.

When should you replace parts?

Consider replacing components.

Replace the chain

Drive links are worn or damaged
The chain no longer maintains proper tension
The chain shows signs of excessive wear

Replace the guide bar

Rails are worn unevenly
The groove is excessively worn
The chain frequently derails despite correct tension