Your chainsaw starts, the engine revs, and the exhaust note sounds normal. Yet the chain sits frozen on the bar. The saw has a voice, but its teeth refuse to move. This fault often comes from an engaged chain brake, a chain set too tight, packed wood chips, or a pinched guide bar. A worn clutch or drive sprocket can also cause the same symptom.
Do not keep squeezing the throttle when the chainsaw blade is not turning. Shut the saw off and disconnect its power before touching the cutting parts. Remove the battery from a cordless model, unplug an electric model, or disconnect the spark-plug boot on a gas saw. Wear work gloves whenever you pull or handle the chain.
The “Blade” Is Really a Chain and Guide Bar
Many owners call the long cutting part a blade. A chainsaw has two main cutting parts. The metal rail is the guide bar. The loop with sharp cutters is the saw chain.
That difference matters during fault finding. The chain may be locked by the brake, stuck inside the bar groove, pinched by wood, or disconnected from the drive sprocket. The bar may also have damaged rails or a seized nose wheel.
Begin by asking one question: Can the chain move by hand after the saw has been fully disconnected from power and the brake has been released?
When the chain cannot move by hand, look for brake, tension, bar, chain, oil, or debris trouble. When it moves freely by hand but stays still under power, look toward the clutch, sprocket, gearbox, battery, switch, or motor.
Quick Chainsaw Fault Chart
| Symptom | Likely Cause | Safe Starting Point |
|---|---|---|
| Engine runs but the chain stays still | Chain brake, clutch, or sprocket | Turn the saw off and release the brake |
| Chain cannot be pulled by hand | Brake on, tight chain, jam, or seized bar nose | Disconnect power and check tension |
| Chain moves until it touches wood | Worn clutch, weak battery, dull chain, or excess tension | Stop cutting and inspect the drive parts |
| Chain became hot before stopping | Low oil flow, blocked groove, or tight chain | Let the bar cool and check oil flow |
| Chain stops during one cut | Bar pinched by the log | Shut the saw off before freeing it |
| Cordless saw starts and stops | Battery protection, heat, overload, or jam | Remove the battery and clear the chain |
| Chain turns at idle | Clutch spring or idle-speed fault | Stop using the saw and book service |
1. The Chain Brake Is Engaged
The chain brake is the most common reason a chainsaw runs while the chain does not turn. The front hand guard controls the brake on most saws. Pushing the guard toward the bar activates it. Pulling the guard back toward the front handle releases it.
The brake may turn on during kickback, while carrying the saw, or after the hand guard bumps a branch. Some saws can also activate the brake through inertia when the machine moves sharply.
Place the switched-off saw on stable ground. Hold the front handle and pull the hand guard back. You should feel or hear a firm click. Do not place your fingers near the cutters.
Once the brake is released, wear gloves and try to pull the chain forward along the top of the bar. The power must remain disconnected during this check.
Never try to defeat an engaged brake by holding the throttle open. The clutch may become extremely hot. Heat can damage the drum, brake band, clutch cover, and nearby plastic.
2. The Chain Is Adjusted Too Tight
A chainsaw chain must sit snug against the bar, but it must still slide around the rails. A chain that feels bolted to the bar creates heavy drag. Small electric and battery saws may refuse to start the chain when tension is too high.
Let the chain cool before changing tension. A hot chain expands during work and contracts after cooling. Adjusting a hot chain too tightly can leave it clamped against the bar later.
Disconnect the power and release the chain brake. Loosen the bar nuts enough for the bar to move. Turn the tension screw or adjustment wheel slightly toward the loose setting. Lift the bar nose during the final adjustment, then tighten the nuts.
With gloves on, pull the chain along the top of the bar. It should move with firm pressure. The drive links should stay inside the groove. Pulling the lower chain away from the bar should expose one or two drive links before the chain snaps back into place.
Check the owner manual because tension controls differ between models. Tool-free wheels, side screws, and front-mounted screws do not all work in the same way.
3. Sawdust Has Packed Around the Drive Sprocket
Wet wood chips can pack beneath the side cover like mud under a boot. Sap, bark strands, dirt, and dry dust may form a hard block around the clutch drum and drive sprocket.
Remove all power and let the machine cool. Take off the side cover under the steps in the owner manual. Brush debris from the clutch area, bar studs, tension pin, oil outlet, and inside face of the cover.
Remove the bar and chain when chips are buried inside the groove. Clean the groove with a bar-groove cleaner made for chainsaws. Clear the oil holes on both sides of the bar.
Inspect each drive link while the chain is off. A bent or burred link may catch inside the groove. Stiff chain joints may also stop the loop from passing around the bar nose.
Replace a chain with cracked links, loose rivets, missing cutters, or badly bent drive links. Do not hammer a damaged chain straight and place it back on the saw.
4. The Bar Is Pinched in the Cut
A branch or trunk can close around the guide bar before the cut is finished. The wood acts like a vise and grips both rails. The engine may keep running, but the chain cannot pass through the closed cut.
Release the throttle at once and stop the saw. Do not pull hard while the chain is running. The bar may break free without warning and throw the moving chain toward your body or nearby wood.
Study how the branch is loaded before trying to free the saw. Compression closes a cut, while tension opens it. Bent limbs may spring with great force when fibres separate.
A plastic felling wedge can open a suitable cut. Never strike the guide bar with a steel hammer. Do not twist the powerhead hard enough to bend the bar rails.
Call a trained tree worker when the tree is storm-damaged, split, leaning, hanging above ground, or touching a building or electrical wire. Loaded wood can move in a blink.
5. The Bar Nose Sprocket Is Seized
Many chainsaw bars have a small wheel at the tip. This nose sprocket lets the chain travel around the end of the bar with less friction. Heat, dirt, damaged bearings, and low oil flow can lock it.
Disconnect the saw and remove the bar and chain. Check the nose sprocket without putting your fingers near the chain cutters. It should turn smoothly without grinding, wobbling, or sticking.
Some bar noses have a grease hole. Others rely only on chain oil. Follow the instructions supplied with the bar. Adding the wrong grease may trap dirt rather than cure the fault.
Replace the guide bar when the nose wheel will not turn, the rails have spread, the groove has become too shallow, or the metal carries heavy blue heat marks. A new chain will not run well on a badly worn bar.
6. The Chain Is Not Receiving Enough Oil
Bar oil forms a slippery film between the chain and guide rails. Without that film, friction rises. The chain becomes hot, tightens against the bar, and may stop moving.
Check the oil tank before looking for a mechanical failure. Fill it with bar-and-chain oil suited to the saw and weather. Ordinary motor oil does not cling to the chain in the same way.
Remove the bar and clean the oil opening on the saw body. Clear the matching holes in the guide bar. Clean the full bar groove so oil can travel toward the nose.
After reassembly, test oil delivery under the method in the owner manual. Many makers direct the owner to run the chain above a pale stump, board, or sheet of cardboard. A fine stripe of oil should appear.
Stop the saw when the chain remains dry, gives off smoke, or develops dark blue marks. The oil pump, filter, hose, worm gear, or oil passage may need dealer repair.
7. The Drive Sprocket Is Worn
The drive sprocket transfers power from the clutch drum to the chain. Its teeth push against the chain’s drive links thousands of times during a work session.
Wear can cut grooves into the sprocket. A worn sprocket may turn the chain with no load, then slip when the cutters touch wood. Clicking, rattling, grinding, or metal dust beneath the cover can point to this fault.
Disconnect the power before removing the side cover. Check for broken teeth, deep grooves, heat damage, sideways movement, and a rough drum bearing.
Replacing a sprocket can call for clutch removal on some gas saws. Many chainsaw clutches have a left-hand thread. Turning one in the wrong direction may damage costly engine parts.
Book dealer service when you do not have prior small-engine repair experience. A trained mechanic can check the sprocket, clutch drum, bearing, brake band, and crankshaft together.
8. The Centrifugal Clutch Is Slipping
Gas chainsaws use a centrifugal clutch. At idle, the clutch shoes remain inward and the chain stays still. As engine speed rises, the shoes move outward and grip the clutch drum.
Worn shoes, broken springs, heat glazing, oil contamination, or a damaged drum can stop the clutch from gripping. The engine may rev normally while the chain remains motionless.
A clutch fault becomes more likely when the chain moves freely by hand, the brake is off, the bar is clear, and the engine reaches full speed. A hot smell or smoke near the side cover is another warning.
Stop testing the throttle when clutch trouble is suspected. Each test adds more heat. The repair should include an inspection of the clutch shoes, springs, drum, bearing, sprocket, and brake band.
9. The Wrong Chain Is Fitted
Bar length does not tell the whole chain size. The chain pitch, gauge, and drive-link count must match the guide bar and drive sprocket.
A chain with drive links that are too thick may jam in the bar groove. A chain with the wrong pitch may sit badly on the sprocket. A loop with the wrong number of links may be impossible to tension correctly.
Read the numbers stamped on the guide bar. Compare them with the chain package. The replacement must match all marked measurements.
Also check chain direction. On the top of the bar, the sharp cutter edges should point toward the bar nose. A backward chain can still turn, but it will scrape the wood instead of cutting it.
10. A Cordless Chainsaw Has Entered Protection Mode
Battery chainsaws can stop the motor when the chain is pinched, the battery becomes hot, or electrical load rises too far. This shutdown guards the battery and motor against damage.
Release the trigger and remove the battery. Let both parts cool in a dry place away from direct sun. Clear trapped wood and chips, then check chain tension and bar oil.
Look at the battery charge display. A weak battery may spin the chain in open air but stop when the cutters touch a log. Cold batteries can also give reduced output until they warm within the approved temperature range.
Try another approved battery when one is available. A saw that stops repeatedly during light cuts may have a brake switch, trigger, controller, gearbox, wiring, or motor fault.
Do not open a lithium-ion battery case. Damaged cells can cause burns or fire. Take a cracked, swollen, leaking, or unusually hot battery out of service.
11. A Corded Chainsaw Has Low Voltage or Gear Damage
A corded saw may hum while the chain stays still. A long, thin extension cord can starve the motor of voltage. The cord and plug may also become hot.
Unplug the saw before checking the bar. Inspect the extension cord for cuts, melted areas, loose ends, and dark marks. Use an outdoor cord with the wire size stated in the manual.
A stripped drive gear can cause the motor to spin without turning the sprocket. Worn motor brushes, a faulty brake switch, and damaged wiring can cause similar trouble.
Motor housing work carries electric shock and fire risk. Dealer repair is the safer choice when the chain and bar move freely but the electric drive does not work.
What It Means When the Chain Moves at Idle
A gas chainsaw chain should stop when the engine settles at normal idle. Continued movement can come from idle speed set too high, a sticking throttle, a broken clutch spring, or worn clutch parts.
Turn the engine off and stop using the saw. A chain that crawls at idle can move across a boot or leg while the operator changes position.
Some manuals allow a small idle adjustment. Do not adjust the carburetor by guesswork. A dealer should inspect the saw when the chain continues moving after an approved idle adjustment.
Safe Check Order
Begin with the chain brake. Shut off the saw, disconnect its power, and pull the hand guard back. Try to move the chain by hand while wearing gloves.
Next, check tension. A snug chain should slide around the bar without hanging below the lower rail. Let a hot chain cool before changing its setting.
After that, remove packed chips and check the bar groove, oil holes, nose sprocket, drive links, and drive sprocket. Look for heat marks, bent metal, cracks, and heavy wear.
When the chain moves by hand but not under power, stop looking at tension alone. The fault may sit inside the clutch, gearbox, switch, or motor.
When to Take the Saw to a Dealer
Book service when the chain brake will not release, the clutch cover smokes, the sprocket wobbles, the bar has cracks, or the motor smells burned.
Dealer care is also the better choice after a hard drop, a chain break, a seized engine, a crushed battery, or contact with metal wire. Damage may remain hidden beneath the cover.
Never remove or bypass the chain brake, hand guard, chain catcher, throttle lock, or safety switch. A chainsaw that runs only after a safety part is defeated is not ready for work.
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Frequently Asked Questions
Why is my chainsaw engine running but the blade is not turning?
The chain brake may be on. Other common causes include a tight chain, packed chips, a pinched bar, low oil flow, a seized bar nose, a worn sprocket, or a slipping clutch.
How do I know whether the chain brake is on?
The front hand guard will usually sit forward when the brake is engaged. Turn the saw off, disconnect its power, and pull the guard back toward the front handle until it clicks.
Should a chainsaw chain turn by hand?
Yes, when the saw is fully disconnected from power and the brake is released. Wear gloves. The chain should pull around the bar with firm hand pressure while its drive links remain inside the groove.
Can a chainsaw chain be too tight to turn?
Yes. Excess tension creates friction and may lock the chain. It can also strain the clutch, sprocket, motor, bar, and bearings.
Why does the chain turn until it touches wood?
The chain may be dull or too tight. The battery may be weak, or the clutch and sprocket may slip under load. Stop forcing the cut and inspect the saw.
Can low chain oil stop the blade?
Yes. Poor oil flow creates heat and drag. The chain can tighten against the bar and stop. Shut the saw down when the bar smokes or the chain looks dry.
Why does my battery chainsaw click but not turn?
The chain may be jammed, the brake may be on, or the battery protection circuit may have stopped the motor. Remove the battery before checking the chain and bar.
Is it safe to rev a chainsaw with the brake on?
Do not hold high throttle against the brake. The clutch and brake parts can overheat quickly. Follow the starting steps in the manual and release the brake before cutting.
The Final Answer
When the blade is not turning on a chainsaw, check the chain brake before anything else. Shut the machine off, disconnect its power, release the brake, and test the chain by hand while wearing gloves.
When the chain remains locked, check tension, packed chips, the bar groove, oil flow, chain fit, and the nose sprocket. When the chain slides freely by hand but refuses to move under power, a worn clutch, drive sprocket, gearbox, switch, or motor may be at fault.
Do not force the throttle against a stuck chain. A small blockage can become a burned clutch or damaged motor within seconds. Stop once smoke, a hot smell, cracked metal, electrical damage, or a brake fault appears, and take the saw to a trained dealer.