How to fix a chainsaw with a stuck chain brake

There’s nothing more annoying than when your chainsaw’s chain brake won’t budge. You’re itching to get back to trimming those overgrown branches or chopping up some firewood, but a stuck brake stops you in your tracks. Don’t worry, though, I’ve put together a handy guide that’ll walk you through how to safely take apart, clean, and swap out any worn bits in your chainsaw’s brake system so you can get back out there.

This guide might not perfectly match your chainsaw model. We do our best to dish out helpful tips for all sorts of DIY fixes, but different models can have their quirks, different steps, parts, and so on. For the most spot-on advice, it’s a good idea to check your chainsaw’s manual or just give us a shout if you’ve got questions.

Why a chainsaw’s chain brake gets stuck

The chain brake on your chainsaw is a super important safety feature, it stops the chain in a flash if there’s a kickback. It usually works with a band or spring-loaded parts that kick into gear when needed. But over time, sawdust, dirt, and caked-up grease can gunk up the brake system. The spring and band can also get worn out or warped from all the use. So, the brake might jam up and stay on, and then you can’t get the chain to move at all.

Sometimes, you might accidentally set off the brake when the chainsaw’s taken apart, which can make the brake band seize up. Other times, the parts inside the mechanism just lock up because of rust or not keeping up with maintenance. Knowing why this happens helps you figure out how to fix it.  

Precautions and safety tips

Before you start tinkering, just remember that chainsaws are powerful and can be risky if you’re not cautious. Safety should always be your main concern. Here’s some advice to consider:

• If working indoors, make sure there is adequate ventilation to prevent the buildup of exhaust fumes. Carbon monoxide poisoning can be a serious risk.
• Wear insulated work gloves to protect your hands from sharp metal parts, pinching hazards and debris.
• Never attempt to service or repair while it is running or when the engine is still warm. Wait for all moving parts to come to a complete stop.
• Exercise extreme caution when working near blades, augers, or any other moving parts. Keep your hands, fingers, and clothing clear of these areas at all times.
• If the appliance has recently been used, give it plenty of time for any hot parts to cool down before working on it. 
• Empty the gas tank before beginning any work. Refill using fresh fuel. 
• Clean up oil spills right away to prevent slipping or other damage. 
• When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.
• Take your time and don’t rush while working to prevent accidents and personal injuries.
• Work in a well-lit area so you can clearly see and access the interior parts.
• Clear your workspace of clutter and other obstacles. Keep children and pets away from the work area.
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause injury.
• Wear safety glasses when working with chemicals, dust or cleaning large debris to prevent injury. 
• When not in use, store the machine in a safe and dry location.

Tools and materials you need

You don’t need a ton of tools to tackle most chain brake issues. Here’s what you’ll usually need:

• Screwdrivers (flathead and Phillips)
• Socket wrenches or a wrench set
• Needle-nose pliers
• A stiff brush or even an old toothbrush
• Cleaning solution (mild solvent or degreaser)
• Rags or paper towels
• Replacement parts (brake spring or brake band) if necessary

Remove the clutch cover and brake assembly

Chainsaws differ a bit, but usually, the chain brake assembly is inside the clutch cover on the side. Here’s how to get to it:

1. If you can, make sure the chain brake is off. If it’s stuck, try gently pushing the brake lever to see if it budges. If not, proceed with caution.
2. Grab a socket wrench or screwdriver to take off the side cover. Usually, you loosen the nuts holding the bar and then remove the cover that holds the brake assembly.
3. Pay attention to how the brake lever, band, and springs are set up. Snapping a few pics with your phone can help you remember how it all goes back together.
4. Carefully slide the brake assembly off the saw. You’ll see a spring mechanism connecting the brake lever to the brake band inside. If you notice anything damaged or worn out, you’ll need to replace it.
5. Now that you’ve got the clutch cover off and can see the brake parts inside, you can spot any gunk or broken bits that might be causing the brake to stick.  

Clean the brake assembly

Usually, a stuck chain brake is just because of old grease or sawdust jamming things up. A good cleaning might fix it without you having to buy new parts. Here’s how to do it:

1. Get rid of loose debris: Grab a rag, paper towel, or soft brush to wipe away sawdust, grime, and old grease from all the surfaces. This gets rid of most of the big stuff.
2. Use a cleaning solution: A mild solvent or degreaser works great to break down hardened oil and resin. Spray or apply it to the brake assembly parts.
3. Scrub the inside surfaces: Use a stiff brush or that old toothbrush to remove stubborn buildup. Pay special attention to the brake band, spring, pivot points, and lever mechanisms. Don’t forget the grooves and corners.
4. Dry it off completely: Wipe away any residue with a clean rag. Since moisture can cause rust, make sure everything’s totally dry before you move on.
5. Once everything’s clean, you can see if any parts are cracked, rusted, or worn out. If the brake works after cleaning, you can start putting things back together. But it’s still smart to check for any serious damage that might mean you need new parts.

Replace worn or damaged parts

Eventually, parts like the brake band, springs, or pins might wear down. If you see any bending, cracks, or a spring that’s lost its tension, you’ll probably need to swap that part out. Swapping out worn parts is key for a long-lasting fix. It might take a little extra time, but replacing these bits makes sure your chainsaw’s brake system works properly down the line.

Here’s what to do:

1. Find the faulty part: The usual suspects are the brake band (a thin metal band around the clutch drum) and the brake spring (a tension spring that tightens the band). Look for discoloration, grooves, or weak tension.
2. Take out the old part: Carefully slide off the brake band or unhook the spring from its spots. Needle-nose pliers can help you grip small areas without messing up other parts.
3. Get the right new part: Parts can be a bit different across brands and models, so check your manual or manufacturer info. You can also hit up our repair help if you need more help finding the right part.
4. Put in the replacement: Lots of brake bands just snap around the clutch drum. You might need to compress springs a bit to get a snug fit. Make sure everything lines up with how it was originally, like in those photos you took.

Reassemble and test the chainsaw

After cleaning and replacing any bad parts, it’s time to reassemble everything. Putting it back together right is important for safety and performance. Here’s how:

1. Put the brake assembly back on: Position the brake band properly around the clutch drum or wherever it needs to go. Make sure the spring connects the external lever to the internal band like before.
2. Reattach the side cover: Line up the cover so the brake lever fits into its slot or pivot point. Tighten up the screws or nuts, not too tight, but snug enough that the cover’s secure.
3. Test the brake lever: Move the brake lever back and forth. When you engage the brake, the band should tighten around the clutch drum; when you disengage it, it should loosen.
4. Put the chain and bar back on (if you took them off): Loop the chain over the bar, making sure the drive links are in the bar groove. Slide the bar onto the saw, then adjust the chain tension as recommended.
5. Do a quick test run: Make sure the spark plug wire is connected or the battery’s back in. Carefully start the chainsaw and engage the brake. The chain should stop spinning right away. Disengage the brake and check that the chain moves freely.

Additional tips 

Thanks for reading! If you need replacement parts, grab your model number and head to AppliancePartsPros.com. We offer over two million parts and most orders arrive in two business days. If you need help finding the right part or placing an order, you can contact our team at 1 (877) 477-7278.

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