Stihl 039 Chainsaw Repair Tips (5 Expert Fixes You Need)

Ever found yourself wrestling with a Stihl 039 chainsaw that just won’t cooperate? It’s a frustrating experience, especially when you’ve got a pile of logs waiting to be transformed into firewood. I’ve been there, countless times. Over the years, I’ve learned that a little knowledge and a few strategic fixes can often bring these workhorses back to life. In this article, I’ll share five expert fixes for your Stihl 039 chainsaw, gleaned from years of hands-on experience and a deep dive into the mechanics of these machines. Let’s get started and get that saw roaring again!

Stihl 039 Chainsaw Repair Tips (5 Expert Fixes You Need)

The Stihl 039 is a reliable saw, but like any piece of machinery, it can develop problems. These fixes are designed to address common issues that I’ve encountered, and hopefully, they’ll help you get your saw back in action.

1. Fuel System Troubleshooting: The Heart of the Matter

A chainsaw’s fuel system is its lifeline. If fuel isn’t flowing correctly, the saw simply won’t run. I remember one particularly cold winter when my 039 refused to start. After much head-scratching, I discovered a simple but crucial issue: a clogged fuel filter.

Common Fuel System Issues

• Clogged Fuel Filter: This is often the first culprit. The filter prevents debris from entering the carburetor. Over time, it can become blocked, restricting fuel flow.
• Stale Fuel: Modern gasoline can degrade quickly, especially when mixed with oil. Stale fuel can gum up the carburetor and fuel lines.
• Leaking Fuel Lines: Cracks or punctures in the fuel lines can cause air leaks, preventing the saw from drawing fuel properly.
• Carburetor Problems: The carburetor mixes fuel and air in the correct proportions. If it’s dirty or damaged, the engine won’t run smoothly.

The Fixes

1. Replace the Fuel Filter: This is a simple and inexpensive fix. I recommend replacing the fuel filter annually, or more often if you use your saw frequently.

   • Procedure: Drain the fuel tank. Locate the fuel filter inside the tank, attached to the fuel line. Use a small hook or wire to pull the filter out. Disconnect the old filter and attach the new one. Reinstall the filter and refill the fuel tank.

   • Use Fresh Fuel: Always use fresh, high-quality gasoline mixed with the correct ratio of two-stroke oil (typically 50:1 for the Stihl 039). I always add a fuel stabilizer to my gasoline to prevent it from degrading.

   • Data Point: Gasoline can start to degrade in as little as 30 days, especially if stored in a non-airtight container. Fuel stabilizer can extend the life of gasoline for up to 12 months.

   • Inspect and Replace Fuel Lines: Carefully inspect the fuel lines for cracks or leaks. If you find any damage, replace the lines.

   • Procedure: Disconnect the fuel lines from the fuel tank and carburetor. Remove the old lines and install the new ones, ensuring they are securely attached.

   • Clean or Rebuild the Carburetor: This is a more complex task, but it can often revive a struggling saw. You can purchase carburetor rebuild kits that include all the necessary parts and gaskets.

   • Procedure: Carefully disassemble the carburetor, noting the location of each part. Clean all the components with carburetor cleaner. Replace any worn or damaged parts with the new ones from the rebuild kit. Reassemble the carburetor and reinstall it on the saw.
   • Personal Story: I once spent an entire afternoon meticulously cleaning a carburetor on an old Stihl saw. It was a tedious process, but the satisfaction of hearing the engine roar back to life was well worth the effort.

   • Adjust Carburetor Settings: The Stihl 039 carburetor typically has three adjustment screws: L (low speed), H (high speed), and LA (idle speed). These screws control the fuel-air mixture at different engine speeds.

   • Procedure: Start the engine and let it warm up. Adjust the L screw until the engine idles smoothly without stalling. Then, carefully adjust the H screw while the engine is running at full throttle. The goal is to find the point where the engine runs smoothly without bogging down or sputtering. Finally, adjust the LA screw to set the desired idle speed.

   • Caution: Incorrect carburetor settings can damage the engine. If you’re not comfortable adjusting the carburetor yourself, it’s best to take the saw to a qualified technician.

2. Ignition System Diagnostics: Sparking the Power

The ignition system is responsible for creating the spark that ignites the fuel-air mixture in the engine. If the ignition system isn’t working correctly, the saw won’t start or run properly.

Common Ignition System Issues

• Faulty Spark Plug: A worn or fouled spark plug can prevent the engine from starting.
• Weak Ignition Coil: The ignition coil generates the high-voltage electricity needed to create a spark. If the coil is weak, it may not produce a strong enough spark to ignite the fuel-air mixture.
• Damaged Flywheel: The flywheel contains magnets that trigger the ignition coil. If the flywheel is damaged or the magnets are weak, the ignition system won’t work correctly.
• Short Circuit: A short circuit in the wiring can prevent the ignition system from functioning properly.

The Fixes

1. Inspect and Replace the Spark Plug: Remove the spark plug and inspect it for damage or fouling. If the plug is worn, cracked, or covered in carbon deposits, replace it with a new one.

   • Procedure: Use a spark plug wrench to remove the old spark plug. Inspect the electrode for wear or damage. If the plug is fouled with carbon deposits, clean it with a wire brush or replace it. Install the new spark plug and tighten it to the correct torque specification.
   • Data Point: A spark plug should be replaced every 100 hours of use or annually, whichever comes first.

   • Test the Ignition Coil: Use a multimeter to test the ignition coil’s resistance. If the resistance is outside the specified range, the coil is faulty and needs to be replaced.

   • Procedure: Disconnect the spark plug wire from the spark plug. Set the multimeter to the resistance setting. Touch the multimeter probes to the ignition coil terminals. Compare the reading to the manufacturer’s specifications.

   • Check the Flywheel: Inspect the flywheel for damage or loose magnets. If the flywheel is damaged, it needs to be replaced.

   • Procedure: Remove the starter cover and inspect the flywheel for cracks or damage. Check the magnets to make sure they are securely attached.

   • Check for Short Circuits: Inspect the wiring for damage or loose connections. Repair any damaged wires or connections.

   • Procedure: Visually inspect the wiring for frayed wires or loose connections. Use a multimeter to check for continuity between the wires and the chassis.

   • Unique Insight: I once had a Stihl 039 that would randomly stall. After hours of troubleshooting, I discovered a tiny crack in the insulation of a wire near the ignition coil. The crack was causing a short circuit that would intermittently kill the engine.

3. Compression Testing: Ensuring Engine Health

Engine compression is crucial for proper combustion. Low compression can indicate worn piston rings, a damaged cylinder, or leaky valves.

Common Compression Issues

• Worn Piston Rings: The piston rings seal the combustion chamber and prevent gases from escaping. Over time, the rings can wear down, reducing compression.
• Damaged Cylinder: Scratches or damage to the cylinder wall can also reduce compression.
• Leaky Valves: The valves seal the intake and exhaust ports. If the valves are worn or damaged, they may not seal properly, causing compression loss.
• Blown Head Gasket: The head gasket seals the cylinder head to the engine block. If the gasket is blown, it can cause compression loss.

The Fixes

1. Perform a Compression Test: Use a compression tester to measure the engine’s compression. A healthy Stihl 039 should have a compression reading of at least 120 PSI.

   • Procedure: Remove the spark plug. Screw the compression tester into the spark plug hole. Pull the starter rope several times until the gauge reaches its maximum reading. Record the reading.
   • Data Point: A compression reading below 100 PSI indicates a serious problem that needs to be addressed.

   • Check for Leaks: If the compression reading is low, check for leaks around the cylinder head, valves, and piston rings.

   • Procedure: Pour a small amount of oil into the spark plug hole. Repeat the compression test. If the compression reading increases, it indicates that the piston rings are worn.

   • Repair or Replace Worn Components: Depending on the cause of the compression loss, you may need to replace the piston rings, cylinder, valves, or head gasket.

   • Procedure: This is a more complex repair that may require specialized tools and knowledge. If you’re not comfortable performing the repair yourself, it’s best to take the saw to a qualified technician.
   • Case Study: I once worked on a Stihl 039 that had extremely low compression. After disassembling the engine, I discovered that the piston rings were completely worn and the cylinder wall was scratched. I replaced the piston, rings, and cylinder, and the saw ran like new.

4. Chain and Bar Maintenance: Cutting Efficiency

A sharp chain and a well-maintained bar are essential for efficient and safe cutting. A dull chain can cause the saw to kick back, and a damaged bar can lead to uneven cuts.

Common Chain and Bar Issues

• Dull Chain: A dull chain requires more effort to cut and can increase the risk of kickback.
• Damaged Chain: Broken or missing teeth on the chain can make it difficult to cut and can also increase the risk of kickback.
• Worn Bar: A worn bar can cause the chain to wobble and can lead to uneven cuts.
• Insufficient Lubrication: Insufficient lubrication can cause the chain and bar to overheat, leading to premature wear and damage.

The Fixes

1. Sharpen the Chain: Use a chainsaw file to sharpen the chain regularly. Sharpening the chain will improve cutting efficiency and reduce the risk of kickback.

   • Procedure: Use a chainsaw file and a file guide to sharpen each tooth on the chain. Follow the manufacturer’s instructions for the correct filing angle and depth.
   • Tip: I always use a depth gauge tool to ensure that the depth gauges are properly set. The depth gauges control how much the chain bites into the wood.

   • Replace the Chain: If the chain is severely damaged or worn, replace it with a new one.

   • Procedure: Remove the old chain from the bar. Install the new chain, making sure that the cutting edges of the teeth are facing in the correct direction.

   • Maintain the Bar: Clean the bar regularly and check it for wear or damage. If the bar is worn or damaged, replace it.

   • Procedure: Clean the bar with a wire brush to remove dirt and debris. Check the bar rails for wear or damage. If the rails are worn, use a bar rail dressing tool to restore them.

   • Ensure Proper Lubrication: Check the oil level regularly and make sure that the chain is receiving adequate lubrication.

   • Procedure: Fill the oil reservoir with chainsaw bar oil. Check the oiler to make sure it is functioning properly. Adjust the oiler if necessary.

   • Data Point: A chainsaw chain should be lubricated every time you use the saw. Insufficient lubrication can cause the chain and bar to overheat and wear out quickly.

5. Starter Mechanism Repair: Getting the Engine Going

The starter mechanism is responsible for turning the engine over until it starts. A faulty starter can prevent the saw from starting.

Common Starter Issues

• Broken Starter Rope: The starter rope can break due to wear and tear.
• Damaged Starter Spring: The starter spring retracts the starter rope after it has been pulled. If the spring is damaged, the rope may not retract properly.
• Worn Starter Pawls: The starter pawls engage the flywheel and turn the engine over. If the pawls are worn, they may not engage properly.
• Dirty Starter Mechanism: Dirt and debris can prevent the starter mechanism from functioning properly.

The Fixes

1. Replace the Starter Rope: If the starter rope is broken, replace it with a new one.

   • Procedure: Remove the starter cover. Remove the old starter rope from the starter pulley. Install the new starter rope, making sure it is properly secured.

   • Replace the Starter Spring: If the starter spring is damaged, replace it with a new one.

   • Procedure: Remove the starter cover. Remove the old starter spring. Install the new starter spring, making sure it is properly tensioned.

   • Replace the Starter Pawls: If the starter pawls are worn, replace them with new ones.

   • Procedure: Remove the starter cover. Remove the old starter pawls. Install the new starter pawls, making sure they are properly aligned.

   • Clean the Starter Mechanism: Clean the starter mechanism with compressed air or a brush to remove dirt and debris.

   • Procedure: Remove the starter cover. Use compressed air or a brush to clean the starter pulley, pawls, and spring.

   • Personal Story: I once had a Stihl 039 that wouldn’t start because the starter pawls were gummed up with sawdust and grease. I cleaned the pawls with carburetor cleaner, and the saw started right up.

Wood Anatomy and Properties: Understanding Your Material

Understanding the wood you’re cutting is essential for efficient and safe chainsaw operation. Different wood species have different densities, moisture contents, and grain patterns, which can affect how the chainsaw performs.

Hardwood vs. Softwood

• Hardwoods: These come from deciduous trees (trees that lose their leaves in the fall), such as oak, maple, and birch. Hardwoods are generally denser and more difficult to cut than softwoods. They also tend to burn hotter and longer, making them ideal for firewood.
• Softwoods: These come from coniferous trees (trees with needles), such as pine, fir, and spruce. Softwoods are generally less dense and easier to cut than hardwoods. They also tend to dry faster, making them a good choice for construction lumber.

Moisture Content

The moisture content of wood can significantly affect its weight, strength, and burning properties.

• Green Wood: This is freshly cut wood with a high moisture content (often over 50%). Green wood is heavy and difficult to cut. It also shrinks and warps as it dries.
• Seasoned Wood: This is wood that has been allowed to dry for a period of time. Seasoned wood has a lower moisture content (typically below 20%) and is lighter and easier to cut. It also burns more efficiently and produces less smoke.

Grain Patterns

The grain pattern of wood can affect its strength and stability.

• Straight Grain: This is wood with a consistent grain pattern that runs parallel to the length of the board. Straight-grained wood is generally stronger and more stable than wood with other grain patterns.
• Spiral Grain: This is wood with a grain pattern that spirals around the length of the tree. Spiral-grained wood is more prone to warping and twisting.
• Interlocked Grain: This is wood with a grain pattern that alternates between left and right. Interlocked-grained wood is difficult to split and can be challenging to work with.

Logging Tool Selection and Maintenance Best Practices

Choosing the right logging tools and maintaining them properly is essential for safety and efficiency.

Chainsaw Selection

• Size and Power: Choose a chainsaw that is appropriate for the size of the trees you will be cutting. A larger, more powerful chainsaw is needed for felling large trees, while a smaller, less powerful chainsaw is sufficient for limbing and bucking.
• Bar Length: Choose a bar length that is slightly longer than the diameter of the trees you will be cutting.
• Safety Features: Look for a chainsaw with safety features such as a chain brake, a throttle lock, and an anti-vibration system.

Other Essential Logging Tools

• Axes: Axes are used for felling small trees, splitting wood, and removing branches.
• Saws: Bow saws and crosscut saws are used for cutting logs to length.
• Wedges: Wedges are used to prevent the saw from pinching during felling.
• Cant Hooks: Cant hooks are used to roll logs.
• Measuring Tools: Measuring tapes and calipers are used to measure logs and lumber.
• Personal Protective Equipment (PPE): Always wear PPE when operating a chainsaw or other logging tools. PPE should include a helmet, safety glasses, hearing protection, gloves, chainsaw chaps, and steel-toed boots.

Tool Maintenance Best Practices

• Clean Tools Regularly: Clean your tools after each use to remove dirt, sawdust, and sap.
• Sharpen Cutting Edges: Keep the cutting edges of your tools sharp to improve efficiency and reduce the risk of injury.
• Lubricate Moving Parts: Lubricate the moving parts of your tools regularly to prevent wear and tear.
• Store Tools Properly: Store your tools in a dry, secure place to protect them from the elements.

Firewood Seasoning Techniques and Safety Considerations

Seasoning firewood is essential for efficient burning and reducing smoke.

Seasoning Techniques

• Stacking: Stack the firewood in a single row with air gaps between the pieces. This will allow air to circulate and dry the wood more quickly.
• Location: Stack the firewood in a sunny, windy location. This will help to evaporate moisture from the wood.
• Covering: Cover the top of the firewood pile with a tarp or roof to protect it from rain and snow.
• Time: Allow the firewood to season for at least six months, or preferably a year or more.

Safety Considerations

• Stacking Stability: Stack the firewood in a stable pile to prevent it from collapsing.
• Pest Control: Inspect the firewood for insects and other pests before bringing it indoors.
• Carbon Monoxide Safety: Never burn firewood in an enclosed space without proper ventilation. Carbon monoxide is a colorless, odorless gas that can be deadly.
• Fire Safety: Keep a fire extinguisher nearby when burning firewood.

Project Planning and Execution: A Step-by-Step Guide

Proper planning is crucial for any wood processing or firewood preparation project.

Step 1: Define Your Objectives

• What are you trying to achieve? Are you felling trees for lumber, preparing firewood for the winter, or clearing land for construction?
• What are your resource constraints? How much time, money, and labor do you have available?

Step 2: Assess the Site

• Identify potential hazards: Look for obstacles such as power lines, fences, and steep slopes.
• Determine the type and size of the trees: This will help you choose the right tools and techniques.
• Assess the soil conditions: This will affect how easily you can move logs and equipment.

Step 3: Develop a Plan

• Outline the steps involved in the project: This will help you stay organized and on track.
• Choose the right tools and equipment: Make sure you have the necessary tools and equipment for each step of the project.
• Develop a safety plan: Identify potential hazards and develop strategies to mitigate them.

Step 4: Execute the Plan

• Follow your plan carefully: Stick to the plan as closely as possible to minimize risks and maximize efficiency.
• Work safely: Always wear PPE and follow safe operating procedures.
• Monitor your progress: Track your progress and make adjustments to the plan as needed.

Step 5: Evaluate the Results

• Did you achieve your objectives? Were you able to complete the project safely and efficiently?
• What did you learn? What could you have done differently to improve the outcome?
• Document your findings: This will help you plan future projects more effectively.

Conclusion: Mastering Your Stihl 039 and the Art of Wood Processing

Repairing a Stihl 039 chainsaw, while sometimes challenging, can be a rewarding experience. By understanding the common issues and applying these expert fixes, you can keep your saw running smoothly for years to come. Remember to prioritize safety, maintain your tools properly, and always plan your projects carefully. With a little knowledge and effort, you can master the art of wood processing and enjoy the satisfaction of transforming raw logs into valuable products. Don’t be afraid to get your hands dirty, learn from your mistakes, and always strive to improve your skills. Happy sawing!

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