Why Does My Chainsaw Chain Keep Coming Loose? Guide

why does my chainsaw chain keep coming loose

Having a chainsaw chain that constantly comes loose can be extremely frustrating. A loose chain affects cutting performance and can even be dangerous if it derails while operating the saw. In this comprehensive guide, I’ll explain the common reasons for chainsaw chains coming loose and provide tips on how to properly tension the chain and perform maintenance to prevent issues.

A properly tensioned chainsaw chain is crucial for smooth cutting and safe operation. When the chain is too loose, it can jump off the guide bar. An overly tight chain strains the engine and causes wear. By understanding what causes chains to loosen and learning how to tension them correctly, you can avoid lots of problems.

Why Does My Chainsaw Chain Keep Coming Loose?

why does my chainsaw chain keep coming loose

There are several potential causes of chains loosening over time and use:

Improper Chain Tensioning

The most obvious reason a chain keeps coming loose is that it wasn’t properly tensioned in the first place. Correctly setting the chain tension is essential for performance and safety. A chain that is too loose can derail or allow the drive sprocket to slip. This results in inefficient cutting, increased wear, and possible kickback. Taking the time to properly adjust the tension prevents issues.

Temperature Changes

Chainsaw chains are designed to stretch slightly in order to maintain tension as they heat up during use. As the chain cools, it contracts again. These temperature changes cause the chain to loosen over time. Additionally, the metal guide bar expands microscopically when heated up while cutting. When it cools, the bar shrinks in size again. This shrinkage also creates slack in an otherwise properly tensioned chain.

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Damaged or Worn Components

With heavy use over time, chainsaw components wear out and become damaged. A worn out drive sprocket can allow the chain to slip and sag. Using a chain that is the wrong size or pitch for your bar and sprocket causes it to not seat correctly. Excessive slack can also occur when the chain tensioning screw breaks or strips out, preventing proper adjustment.

Chain Stretching

The extreme stresses placed on chainsaw chains causes them to naturally stretch and elongate with heavy use. High chain speeds combined with intense friction results in the chain joints loosening up imperceptibly. As the chain stretches, it requires more frequent adjustments to account for the slack. Once stretched too far, it must be replaced.

How to Properly Tension Your Chainsaw Chain

Correctly tensioning the chain is a crucial skill for any chainsaw user. Here is a step-by-step guide to proper chain tensioning:

Step-by-Step Guide

  1. Ensure the chainsaw is deactivated and the bar and chain are cool to the touch. Loosen the bar nuts that hold the clutch cover in place. The clutch cover must be loosened to allow chain adjustments.
  2. Locate the chain tensioning screw, usually at the rear of the chainsaw. Use a screwdriver or a scrench tool to turn the tension screw clockwise. This draws the guide bar forward, tightening the chain.
  3. Keep tensioning the chain until it no longer sags from the underside of the bar. Gently pull the chain around the bar by hand. It should have just a little give, with no sagging or over-tightness.
  4. Hold the bar nose up and pull the chain. Then perform a “snap” test by pulling the chain downward. It should quickly snap back up into place. If it limply drops down, it needs more tension.
  5. Tighten down the bar nuts while continuing to lift up on the bar nose. Double check the tension and make adjustments as needed.
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Tips for Maintaining Proper Chain Tension

  • Check the chain tension frequently, especially when the saw is still warm after use. Adjust as needed to account for temperature changes.
  • When installing a new chain, tension it fully with the chain warm to account for the initial stretch-in period.
  • Make small tension adjustments as needed rather than waiting for the chain to get very loose.
  • Replace the chain once it has stretched so far it won’t tension properly. Chains do wear out over time.
  • Inspect the guide bar and drive sprocket for wear. Damage to these parts can prevent proper chain tensioning.

Chainsaw Maintenance Tips

Proper chainsaw maintenance helps prevent many issues, including loose chains. Here are some key maintenance tips:

Keeping the Chain Sharp

A sharp chain cuts cleaner and requires less effort on the saw’s part. The engine strains less, and the chain stays seated on the bar better. Dull, damaged chain teeth increase friction. Regular sharpening or professional chain sharpening services will keep it cutting like new.

Cleaning the Air Filter

A clogged air filter starves the engine of air, resulting in loss of power. This strains the engine and makes it less able to properly tension and drive the chain. Regular filter cleaning or replacement keeps the engine running optimally.

Using Fresh Gasoline

Stale old gas causes engine damage from deposits and varnish buildup. Two-cycle engine oil additive breaks down over time as well. Always use fresh fuel and properly measured oil for best performance and life from your chainsaw.

Common Chainsaw Chain Issues and Solutions

Chainsaw chains can develop issues beyond just looseness. Here are solutions to some other common problems:

Chain Not Cutting Properly

A chain that is dull, damaged, or improperly sharpened will cut slowly and unevenly. Regularly inspect and sharpen the teeth with a file guide. Replace excessively worn chains. Make sure each tooth is uniformly sharpened.

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Chain Making a Crooked Cut

A crooked cutting chain indicates issues with the guide bar or chain being misaligned. Inspect the guide bar rails for straightness and wear. Make sure the chain is properly seated in the bar groove. Tensioning the chain can help align it properly.

Read here for more details- https://www.fs.usda.gov/t-d/pubs/htmlpubs/htm06672804/page03.htm


Loose or problematic chainsaw chains are usually preventable with proper maintenance and tensioning. Regularly check the tension, especially when heated from use. Keep the chain sharp, components in good repair, and the engine tuned up. With a little chainsaw know-how and consistent care, you can avoid the aggravation of a loose chain. Properly tensioned and maintained chains will cut cleanly and safely.

Frequently Asked Questions

How often should I adjust my chainsaw chain tension?

Check the tension every time you refuel and make adjustments as needed. Also check it routinely as the saw heats up and cools from use.

What are the signs of a worn-out chainsaw chain?

Excessive stretching, damaged or missing drive links, badly worn cutters, or cracking are signs a chain should be replaced. A very dull chain that won’t sharpen properly may also indicate replacement is needed.

Can I use vegetable oil as a chain lubricant?

No, only use chainsaw-specific bar and chain oil. Vegetable oils lack tackiness and will not properly lubricate the chain, leading to damage.

How do I know if my chainsaw chain is installed correctly?

When properly installed, the chain should seat smoothly in the guide bar groove. It lines up on the drive sprocket and can be tensioned without binding or kinking. The chain cutters face the proper direction.

What should I do if my chainsaw chain keeps coming off the bar?

A chain derailing indicates an issue with the tension, guide bar, or drive components. Inspect the bar rails for burrs or damage, and make sure the chain size matches the bar. Adjust the tension carefully and replace damaged parts if needed.

In summary, loose chainsaw chains are typically caused by improper tensioning, temperature changes, worn components, or natural chain stretching over time. Regularly checking and adjusting the tension, as well as maintaining the saw, can prevent many issues. With proper care and maintenance, chainsaw chains can be kept tight and cutting smoothly.

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