A chainsaw is no good to you when the chain around the guide bar stops moving. A damaged guide bar can impact how the chain performs on the bar, but there are other items that can affect the chain’s rotation.
A Stihl chainsaw chain will not move or turn on the bar when the chain brake is engaged; the bar and chain are not sufficiently lubricated; the chain tension is too tight, or the clutch pads are worn.
Turn the chainsaw off and wait for all moving parts to stop before checking the chain. Wear protective gloves when working with the sharp chain.
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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
Reasons a Stihl Chain Won’t Turn, Move or Spin
Chain Brake Activated on a Stihl Chainsaw
A Stihl chainsaw has a guard in front of the handle that acts as a safety device. This guard is the chain brake. It reduces the possibility of injury in the event of a kickback where the chainsaw kicks up and back at the user.
When there is a kickback the chain brake will stop the chain. The chain brake can also be manually pushed forward to stop the chain as well. This is done when starting the chainsaw.
Check that you don’t have the chain brake activated by pulling the guard to the rear of the saw to disengage it and allow the chain to move.
Lack of Bar and Chain Oil on a Stihl Chainsaw
The bar and chain must be kept lubricated or you will experience increased friction and a buildup of heat. The chain will begin to move very slowly without sufficient lubrication.
To check for sufficient oil on the bar, run your chainsaw at about 3/4 throttle while holding the saw the bar a foot off a flat surface. You should see a line of oil on the ground after running the saw for a few minutes.
If you don’t see oil, you aren’t getting good lubrication. Check the bar to make sure it is in good condition. Replace a worn or damaged guide bar. Next, check the oil channel and clean it out if it is clogged.
Always make sure your Stihl bar and chain stay well lubricated. Refill the bar and chain oil every time you fill up with fuel so you don’t run out. Note: If you are running too thin of oil, you may run out of chain oil before it’s time to refill the fuel tank.
Change Bar and Chain Oil with the Ambient Temperature
- Thinner oil for cold temperatures: Oil will thicken and become tackier in cold temperatures. Stihl offers a winter chainsaw oil that works well in cold temperatures.
- Standard weight for warmer temperatures:
Stihl Chain Tension is Too Tight
The chain should be adjusted regularly as it will become longer as you use it. When the chain is adjusted too tight to the bar, it will not rotate around the bar.
Adjust the chain tension on a STIHL chainsaw:
- Remove the spark plug wire.
- Unlock the chain brake.
- Loosen the bar retaining nuts that hold on the cover over the clutch and chain brake.
- Hold the nose of the bar up.
- Turn the tensioning screw counter-clockwise to loosen the chain and clockwise to tighten the chain.
- Once you achieve the correct tension, tighten the bar retaining nuts while continuing to hold the bar nose up.
You want the chain to sit securely around the bar, but still able to move easily. You don’t want it too loose it hangs from the guide bar.
You want the chain to sit securely around the bar, but you still need to be able to move easily. You don’t want it so loose that it hangs from the guide bar. Once you achieve the correct tension, tighten the bar nut(s).
Worn Clutch Pads on a Stihl Chainsaw
The clutch pads can wear over time. When this happens, they won’t engage the clutch drum to turn the chain. The clutch assembly on a Stihl chainsaw will need to be replaced.
Reasons a Chain Moves at Idle Speed on a Stihl Chainsaw
Carburetor Needs Adjustment on a Stihl Chainsaw
There are adjustment screws on the carburetor that adjust the mixture of fuel to air. One of the adjustments screws, the “LA Screw” adjusts the idle speed affecting chain movement.
To adjust the idle speed so the chain doesn’t move while idling, begin by turning the screw counter-clockwise until the chain stops moving. Then continue to turn the screw counter-clockwise a 1/4 turn further.
Worn Clutch Springs on a Stihl Chainsaw
On a Stihl chainsaw centrifugal clutch, there are springs that retract the clutch shoes. When the engine speeds up, the centrifugal force pushes the shoes outward making contact with the drum. The drum spins making the chain move on the bar.
When the engine slows down, the spring retracts the clutch shoes and the chain is supposed to stop moving. If your chain continues to move, you may have worn springs that need to be replaced on your Stihl chainsaw.