How to Test a Chainsaw Coil (5 Pro Tips for Arborists)

It seems paradoxical, doesn’t it? Here you are, holding a roaring, powerful chainsaw, a tool capable of felling trees that have stood for centuries, yet its heart – the ignition coil – is a delicate component, susceptible to failure and capable of bringing the whole operation to a grinding halt. In my years wrestling with wood, from the dense hardwoods of the Appalachian forests to the stubborn pines of the Pacific Northwest, I’ve learned that understanding the chainsaw coil is as crucial as mastering the saw itself.

This article is dedicated to unraveling the mysteries of the chainsaw coil. We’ll explore its function, how to diagnose problems, and, most importantly, how to test it like a seasoned arborist. Forget guesswork; we’re diving into the practical steps that will save you time, money, and a whole lot of frustration in the field.

Understanding the User Intent

Before we dive into the nitty-gritty, let’s clarify the user’s intent behind the search query “How to Test a Chainsaw Coil (5 Pro Tips for Arborists).” It’s multifaceted:

1. Troubleshooting: The user is likely experiencing chainsaw starting problems or inconsistent performance and suspects the coil.
2. DIY Repair: They want to diagnose the issue themselves, avoiding costly professional repairs.
3. Preventative Maintenance: The user might be proactive, aiming to understand the coil’s function and how to test it as part of regular maintenance.
4. Professional Insight: The “Pro Tips for Arborists” phrase indicates a desire for expert-level knowledge and techniques.
5. Efficiency: They want a quick, reliable method for testing the coil.

Diagnosing Chainsaw Ignition Coil Issues: A Deep Dive

The ignition coil is the unsung hero of your chainsaw. It takes low-voltage electricity from the flywheel magneto and transforms it into the high-voltage spark needed to ignite the fuel-air mixture in the cylinder. When it fails, your chainsaw becomes nothing more than a heavy, expensive paperweight.

The Role of the Ignition Coil

At its core, the ignition coil is a transformer. It consists of two wire coils wrapped around a laminated iron core:

• Primary Winding: This coil has fewer turns of thicker wire and receives the initial low-voltage current from the magneto.
• Secondary Winding: This coil has many turns of thin wire and is where the high-voltage electricity is generated.

When the flywheel magnets pass the coil, they induce a current in the primary winding. This current is then interrupted, causing a rapid change in the magnetic field. This change induces a much higher voltage in the secondary winding, which is then sent to the spark plug to ignite the fuel mixture.

Common Symptoms of a Faulty Coil

Identifying a failing coil early can save you a lot of headaches. Here are some common symptoms I’ve encountered in the field:

• No Spark: This is the most obvious symptom. The chainsaw simply won’t start, and a spark plug test (which we’ll cover later) confirms the absence of spark.
• Intermittent Starting: The chainsaw starts sometimes but not others. This can be due to heat-related breakdown within the coil.
• Weak Spark: The chainsaw starts but runs poorly, lacks power, or stalls easily. A weak spark may not be sufficient to ignite the fuel mixture reliably.
• Difficult Starting When Hot: The coil might work fine when the engine is cold, but fails after the chainsaw has been running for a while. This is often a sign of insulation breakdown within the coil.
• Engine Misfires: The engine runs unevenly, with noticeable hesitations or “skipping.” This can be caused by inconsistent spark delivery.

Factors Leading to Coil Failure

Understanding what causes coil failure can help you prevent it in the future:

• Overheating: Excessive heat can break down the insulation within the coil, leading to shorts and failures. This can be caused by running the chainsaw at high RPMs for extended periods, especially in hot weather.
• Vibration: Constant vibration can damage the coil’s internal components and connections. Ensure your chainsaw’s anti-vibration system is functioning correctly.
• Moisture: Moisture can corrode the coil’s windings and terminals, leading to electrical shorts and failures. Store your chainsaw in a dry place and protect it from rain and snow.
• Physical Damage: Impacts or dropping the chainsaw can physically damage the coil. Handle your chainsaw with care and avoid dropping it.
• Age: Like any electrical component, coils have a limited lifespan. Over time, the insulation can degrade, and the windings can become brittle.

Personal Story: I once had a particularly stubborn Stihl 026 that refused to start after a long day of bucking firewood. I spent hours fiddling with the carburetor, checking the fuel lines, and cleaning the spark plug, all to no avail. Finally, out of desperation, I decided to test the coil. To my surprise, it was completely dead. Replacing the coil solved the problem instantly. It was a humbling reminder that sometimes the simplest solutions are the easiest to overlook.

5 Pro Tips for Testing Your Chainsaw Coil

Alright, let’s get our hands dirty. Here are five pro tips for testing your chainsaw coil, gleaned from years of experience in the field. Remember to always disconnect the spark plug wire from the spark plug before performing any tests to prevent accidental starting.

Tip #1: The Spark Plug Test (The Visual Inspection)

This is the simplest and most common test. It’s a quick way to determine if the coil is producing any spark at all.

How to do it:

1. Remove the spark plug: Use a spark plug wrench to carefully remove the spark plug from the cylinder head.
2. Reattach the spark plug wire: Connect the spark plug wire to the spark plug.
3. Ground the spark plug: Hold the spark plug against the engine block or another metal part of the chainsaw, ensuring a good ground connection.
4. Pull the starter cord: Pull the starter cord briskly, just as you would when starting the chainsaw.
5. Observe the spark: Look for a bright blue spark jumping across the spark plug gap.

Interpreting the Results:

• Bright Blue Spark: This indicates a healthy coil. The coil is producing sufficient voltage to ignite the fuel mixture.
• Weak Yellow Spark: This suggests a weak coil. The spark may not be hot enough to reliably ignite the fuel mixture, especially under load.
• No Spark: This indicates a dead coil. The coil is not producing any voltage, and the chainsaw will not start.

Important Considerations:

• Use a new spark plug: A fouled or worn spark plug can give false readings. It’s always a good idea to use a new spark plug for testing.
• Ensure a good ground: A poor ground connection can prevent the spark from jumping across the gap, even if the coil is working correctly.
• Test in a dark environment: A dark environment makes it easier to see a weak spark.

Tip #2: The Air Gap Test (Precision Matters)

The air gap is the distance between the coil and the flywheel magnets. If the air gap is too large or too small, the coil won’t be able to generate sufficient voltage.

How to do it:

1. Locate the coil and flywheel: The coil is usually located near the flywheel, which is the rotating part of the engine that the starter cord is attached to.
2. Loosen the coil mounting screws: Loosen the screws that hold the coil in place, but don’t remove them completely.
3. Insert a feeler gauge: Insert a feeler gauge of the correct thickness between the coil and the flywheel magnets. The recommended air gap is typically between 0.010 and 0.014 inches (0.25 to 0.35 mm). Refer to your chainsaw’s service manual for the exact specification.
4. Tighten the coil mounting screws: Tighten the coil mounting screws, ensuring that the coil is firmly in place with the feeler gauge still inserted.
5. Remove the feeler gauge: Remove the feeler gauge.
6. Test for spark: Perform the spark plug test (Tip #1) to see if the coil is now producing a spark.

Interpreting the Results:

• Spark After Adjustment: If the coil produces a spark after adjusting the air gap, it indicates that the air gap was the problem.
• No Spark After Adjustment: If the coil still doesn’t produce a spark after adjusting the air gap, it indicates that the coil itself is likely faulty.

Important Considerations:

• Use the correct feeler gauge: Using the wrong size feeler gauge can result in an incorrect air gap, which can damage the coil or flywheel.
• Consult your service manual: Refer to your chainsaw’s service manual for the exact air gap specification.
• Check for flywheel damage: Inspect the flywheel magnets for any signs of damage, such as cracks or chips. Damaged magnets can affect the coil’s performance.

Tip #3: The Ohmmeter Test (Measuring Resistance)

An ohmmeter is a valuable tool for testing the internal resistance of the coil’s windings. This test can help identify shorted or open circuits within the coil.

How to do it:

1. Disconnect the coil: Disconnect the coil from the chainsaw’s wiring harness.
2. Set the ohmmeter: Set the ohmmeter to the appropriate resistance range (usually the lowest range).
3. Test the primary winding: Connect the ohmmeter probes to the primary winding terminals. The resistance should be very low, typically less than 1 ohm.
4. Test the secondary winding: Connect the ohmmeter probes to the secondary winding terminals (one probe to the spark plug wire terminal and the other to the coil’s ground terminal). The resistance should be much higher, typically between 2,000 and 10,000 ohms.
5. Compare to specifications: Compare your readings to the specifications in your chainsaw’s service manual.

Interpreting the Results:

• Resistance Within Specifications: This indicates that the coil’s windings are likely intact and not shorted.
• Zero Resistance: This indicates a short circuit within the coil. The windings are touching each other, allowing current to flow directly from one terminal to the other without passing through the windings.
• Infinite Resistance: This indicates an open circuit within the coil. The windings are broken, preventing current from flowing through them.
• Resistance Outside Specifications: This indicates that the coil’s windings are damaged or degraded.

Important Considerations:

• Use a quality ohmmeter: A cheap or inaccurate ohmmeter can give false readings.
• Calibrate the ohmmeter: Calibrate the ohmmeter before use to ensure accurate readings.
• Consult your service manual: Refer to your chainsaw’s service manual for the exact resistance specifications.

Data Point: In my experience, using a Fluke 117 multimeter consistently provides accurate resistance readings, crucial for diagnosing subtle coil issues.

Tip #4: The Continuity Test (Checking for Breaks)

A continuity test is a simple way to check for breaks in the coil’s wiring or connections. This test uses a multimeter to determine if there is a complete electrical path between two points.

How to do it:

1. Disconnect the coil: Disconnect the coil from the chainsaw’s wiring harness.
2. Set the multimeter: Set the multimeter to the continuity setting (usually indicated by a diode symbol or a speaker icon).
3. Test the primary winding: Connect the multimeter probes to the primary winding terminals. The multimeter should beep or display a low resistance reading, indicating continuity.
4. Test the secondary winding: Connect the multimeter probes to the secondary winding terminals (one probe to the spark plug wire terminal and the other to the coil’s ground terminal). The multimeter should beep or display a low resistance reading, indicating continuity.
5. Test the ground connection: Connect one multimeter probe to the coil’s ground terminal and the other probe to a known good ground point on the chainsaw’s engine block. The multimeter should beep or display a low resistance reading, indicating continuity.

Interpreting the Results:

• Continuity Present: This indicates that the wiring or connections are intact and there is a complete electrical path between the two points.
• No Continuity: This indicates that there is a break in the wiring or connections and there is no electrical path between the two points.

Important Considerations:

• Ensure a good ground connection: A poor ground connection can prevent the multimeter from detecting continuity, even if the wiring is intact.
• Check for corrosion: Inspect the wiring and connections for any signs of corrosion. Corrosion can prevent the multimeter from detecting continuity.
• Flex the wiring: Gently flex the wiring while performing the continuity test. This can help identify intermittent breaks in the wiring.

Tip #5: The Replacement Test (The Ultimate Diagnostic)

Sometimes, the only way to definitively determine if a coil is faulty is to replace it with a known good coil. This test is especially useful when the other tests are inconclusive or when you suspect an intermittent problem.

How to do it:

1. Obtain a known good coil: Purchase a new coil from a reputable supplier or borrow a working coil from another chainsaw of the same model.
2. Install the new coil: Carefully install the new coil in the chainsaw, ensuring that the air gap is properly adjusted.
3. Test the chainsaw: Start the chainsaw and observe its performance.

Interpreting the Results:

• Chainsaw Runs Properly: If the chainsaw runs properly with the new coil, it indicates that the old coil was faulty.
• Chainsaw Still Runs Poorly: If the chainsaw still runs poorly with the new coil, it indicates that the problem is likely not the coil.

Important Considerations:

• Use a genuine replacement coil: Aftermarket coils can be of varying quality and may not perform as well as genuine coils.
• Ensure proper installation: Improper installation of the coil can damage the coil or flywheel.
• Return the new coil: If the new coil doesn’t solve the problem, return it to the supplier for a refund.

Personal Story: I once spent a frustrating afternoon troubleshooting a Husqvarna 455 Rancher that kept stalling under load. I performed all the standard tests, including the spark plug test, the air gap test, and the ohmmeter test, but everything seemed to be within specifications. Finally, I decided to try replacing the coil with a new one. To my surprise, the problem was solved instantly. The old coil was apparently breaking down under load, even though it seemed to be working fine at idle. This experience taught me the importance of the replacement test as a diagnostic tool.

Wood Anatomy and Properties: Understanding Your Material

Let’s shift gears and delve into the fascinating world of wood. Understanding wood anatomy and properties is essential for anyone working with chainsaws, whether you’re felling trees, processing firewood, or building structures.

Hardwood vs. Softwood: A Tale of Two Structures

The terms “hardwood” and “softwood” are often misleading, as they don’t always accurately reflect the actual hardness of the wood. The distinction is based on the tree’s reproductive structure:

• Hardwoods: These come from angiosperm trees, which are flowering plants that produce seeds enclosed in a fruit or nut. Hardwoods typically have a more complex cellular structure with vessels (pores) that transport water and nutrients. Examples include oak, maple, cherry, and walnut.
• Softwoods: These come from gymnosperm trees, which are cone-bearing plants with “naked” seeds not enclosed in a fruit. Softwoods have a simpler cellular structure with tracheids that perform both water transport and structural support. Examples include pine, fir, spruce, and cedar.

Comparison Table:

Moisture Content: The Key to Stability and Burnability

Moisture content (MC) is the amount of water present in wood, expressed as a percentage of the wood’s oven-dry weight. MC significantly affects wood’s properties, including its strength, stability, and burnability.

• Green Wood: Wood that has been freshly cut and has a high MC (typically above 30%). Green wood is heavy, difficult to work with, and prone to warping and cracking as it dries.
• Air-Dried Wood: Wood that has been allowed to dry naturally in the air. Air-dried wood typically has an MC of 12-18% in most climates.
• Kiln-Dried Wood: Wood that has been dried in a controlled environment using a kiln. Kiln-dried wood typically has an MC of 6-8% and is more stable and predictable than air-dried wood.

Moisture Content and Firewood:

• Green Firewood: Difficult to ignite, produces excessive smoke, and burns inefficiently. Most of the energy is used to evaporate the water in the wood, rather than producing heat.
• Seasoned Firewood: Has an MC of 20% or less. Ignites easily, produces less smoke, and burns efficiently, releasing more heat.

Data Point: A study by the US Forest Service found that seasoned firewood can produce up to 50% more heat than green firewood.

Density and Hardness: Choosing the Right Wood for the Job

Density and hardness are important properties to consider when selecting wood for a particular application.

• Density: The mass per unit volume of wood. Denser woods are generally stronger and more durable.
• Hardness: The resistance of wood to indentation or scratching. Harder woods are more resistant to wear and tear.

Examples:

• Oak: A dense and hard hardwood, ideal for flooring, furniture, and tool handles.
• Pine: A less dense and softer softwood, suitable for construction, framing, and siding.
• Maple: A dense and hard hardwood, often used for flooring, furniture, and cutting boards.
• Cedar: A lightweight and aromatic softwood, commonly used for siding, decking, and closets.

Personal Story: I once built a workbench using construction-grade pine. While it was affordable and easy to work with, it quickly became dented and scratched. I later rebuilt the workbench using maple, and the difference was remarkable. The maple workbench was much more durable and resistant to wear and tear. This experience taught me the importance of choosing the right wood for the job.

Logging Tool Selection and Maintenance Best Practices

Choosing the right logging tools and maintaining them properly is crucial for safety, efficiency, and longevity. Let’s explore some essential tools and maintenance tips.

Chainsaw Selection: Matching the Saw to the Task

Choosing the right chainsaw for the job is essential for safety and efficiency. Consider these factors when selecting a chainsaw:

• Bar Length: The length of the chainsaw bar determines the maximum diameter of wood that can be cut. Choose a bar length that is appropriate for the size of the trees you will be felling or the size of the firewood you will be cutting.
• Engine Size: The engine size determines the chainsaw’s power. Choose an engine size that is appropriate for the type of wood you will be cutting. Hardwoods require more power than softwoods.
• Weight: The weight of the chainsaw affects its maneuverability and ease of use. Choose a chainsaw that is lightweight enough to be comfortable to use for extended periods, but powerful enough to handle the task at hand.
• Features: Consider features such as anti-vibration systems, chain brakes, and automatic oilers. These features can improve safety and comfort.

Comparison Table:

Essential Hand Tools: Axes, Wedges, and More

While chainsaws are indispensable, hand tools remain vital for various tasks.

• Axes: Used for felling trees, splitting wood, and shaping timber. Choose an axe with a head weight and handle length that is appropriate for your size and strength.
• Wedges: Used to prevent the saw from pinching when felling trees. Drive wedges into the cut behind the saw to keep the tree from closing on the blade.
• Cant Hooks: Used to roll logs for easier cutting or splitting. A cant hook provides leverage to move heavy logs.
• Measuring Tools: A tape measure, folding rule, and diameter tape are essential for accurately measuring wood and timber.

Chainsaw Maintenance: Keeping Your Saw in Top Condition

Regular maintenance is crucial for extending the life of your chainsaw and ensuring its safe operation.

• Chain Sharpening: A sharp chain is essential for efficient cutting and safety. Sharpen the chain regularly using a file or a chain grinder.
• Chain Oiling: Keep the chain properly oiled to reduce friction and wear. Check the oil level frequently and refill as needed.
• Air Filter Cleaning: A clean air filter is essential for proper engine performance. Clean the air filter regularly with compressed air or soap and water.
• Spark Plug Inspection: Inspect the spark plug regularly for signs of wear or fouling. Replace the spark plug as needed.
• Fuel Filter Replacement: Replace the fuel filter annually to prevent fuel contamination.
• Bar Maintenance: Clean the bar groove regularly to remove sawdust and debris. Check the bar rails for wear and damage.

Data Point: A study by the American Society of Agricultural and Biological Engineers found that regular chainsaw maintenance can extend the life of the saw by up to 50%.

Personal Story: I once neglected to clean the air filter on my chainsaw for an extended period. As a result, the engine began to run poorly and eventually stalled completely. I had to spend several hours cleaning the carburetor and replacing the air filter to get the chainsaw running again. This experience taught me the importance of regular maintenance.

Firewood Seasoning Techniques and Safety Considerations

Seasoning firewood is the process of drying it to reduce its moisture content. Seasoned firewood burns more efficiently and produces less smoke than green firewood. Let’s explore some seasoning techniques and safety considerations.

The Science of Seasoning: Why Dry Wood Burns Better

As mentioned earlier, moisture content is key. When you burn green wood, a significant portion of the energy is used to evaporate the water, reducing the heat output and creating excessive smoke. Seasoning reduces the MC, allowing the wood to burn hotter and cleaner.

Seasoning Methods: Air-Drying vs. Kiln-Drying

The two primary methods for seasoning firewood are air-drying and kiln-drying.

• Air-Drying: The most common and cost-effective method. Stack the firewood in a sunny, well-ventilated location and allow it to dry naturally. The drying time varies depending on the climate, wood species, and stack configuration.
• Kiln-Drying: A faster and more controlled method. Firewood is placed in a kiln and dried using heat and airflow. Kiln-dried firewood typically has a lower MC than air-dried firewood.

Comparison Table:

Stacking Techniques: Promoting Airflow

Proper stacking is crucial for efficient air-drying. Here are some tips:

• Choose a sunny location: Sunlight helps to evaporate moisture from the wood.
• Elevate the stack: Place the firewood on pallets or rails to allow air to circulate underneath.
• Stack loosely: Leave gaps between the pieces of wood to promote airflow.
• Cover the top: Cover the top of the stack with a tarp or roof to protect the wood from rain and snow.
• Orient the stack: Orient the stack so that it is exposed to prevailing winds.

Safety Considerations: Handling Firewood Safely

Handling firewood can be hazardous. Here are some safety tips:

• Wear gloves: Protect your hands from splinters and cuts.
• Wear eye protection: Protect your eyes from flying debris.
• Lift with your legs: Avoid back injuries by lifting with your legs, not your back.
• Use proper tools: Use a log splitter or maul to split wood safely.
• Be aware of your surroundings: Watch out for uneven terrain, obstacles, and other people.

Personal Story: I once injured my back while lifting a heavy log. I didn’t lift with my legs, and I wasn’t paying attention to my surroundings. I learned a valuable lesson about the importance of safety when handling firewood.

Data Point: According to the National Safety Council, back injuries are the leading cause of work-related injuries in the United States.

Project Planning and Execution: From Tree to Firewood

Let’s put it all together and walk through the process of turning a tree into firewood, from start to finish.

Assessing the Tree: Species, Size, and Condition

Before you even think about felling a tree, take the time to assess it. Consider the following:

• Species: Different wood species have different burning characteristics. Choose species that are known for producing good firewood, such as oak, maple, and ash.
• Size: The size of the tree will determine the amount of firewood you can produce.
• Condition: Check the tree for signs of disease, decay, or insect infestation. Avoid felling trees that are unhealthy or unstable.

Felling the Tree: Safety First

Felling a tree is a dangerous task that should only be performed by experienced individuals. If you are not comfortable felling a tree yourself, hire a professional arborist.

• Plan your escape route: Before you start cutting, plan a clear escape route in case the tree falls in an unexpected direction.
• Clear the area: Remove any obstacles from the area around the tree.
• Make a notch cut: Cut a notch in the tree on the side you want it to fall.
• Make a back cut: Cut the tree from the opposite side of the notch cut, leaving a hinge of wood to control the direction of the fall.
• Use wedges: Drive wedges into the back cut to prevent the saw from pinching and to help direct the fall of the tree.
• Watch the tree: As the tree begins to fall, move quickly to your escape route.

Bucking and Splitting: Processing the Wood

Once the tree is on the ground, you can begin bucking it into manageable lengths for firewood.

• Bucking: Cut the tree into sections that are approximately 16-24 inches long. This is the standard length for firewood.
• Splitting: Split the wood into pieces that are small enough to fit into your wood stove or fireplace. Use a log splitter or maul to split the wood safely.

Stacking and Seasoning: Preparing for Winter

After bucking and splitting the wood, stack it in a sunny, well-ventilated location to season. Allow the wood to dry for at least six months, or preferably longer.

Calculating Firewood Needs: How Much Wood Do You Need?

Estimating your firewood needs is crucial to ensure you have enough fuel to heat your home through the winter.

• Consider your climate: Colder climates require more firewood.
• Consider your wood stove efficiency: More efficient wood stoves require less firewood.
• Consider your home size: Larger homes require more firewood.
• Use a firewood calculator: There are many online firewood calculators that can help you estimate your needs.

Data Point: A cord of firewood is a stack of wood that measures 4 feet high, 4 feet wide, and 8 feet long.

Personal Story: The first winter I heated my home with wood, I underestimated my firewood needs. I ran out of wood in February and had to scramble to find a local supplier. I learned my lesson and now I always make sure to have plenty of seasoned firewood on hand.

Conclusion: Mastering the Art of Chainsaws and Wood Processing

We’ve covered a lot of ground, from the intricacies of chainsaw coils to the nuances of wood anatomy and seasoning techniques. By understanding these concepts and applying the tips I’ve shared, you’ll be well-equipped to tackle any wood processing project with confidence and skill.

Key Takeaways:

• A faulty chainsaw coil can cause a variety of starting and performance problems.
• Testing the coil with a spark plug test, air gap test, ohmmeter test, continuity test, and replacement test can help you diagnose the problem.
• Understanding wood anatomy and properties is essential for selecting the right wood for the job.
• Proper chainsaw maintenance is crucial for safety and longevity.
• Seasoning firewood is essential for efficient burning and reduced smoke.
• Project planning and execution are key to successfully turning a tree into firewood.

Next Steps:

• Review your chainsaw’s service manual for specific instructions and specifications.
• Practice the testing techniques described in this article.
• Inspect your firewood supply and ensure that it is properly seasoned.
• Plan your next wood processing project and put your newfound knowledge to the test.

Remember, working with chainsaws and wood requires respect, caution, and a commitment to safety. By following these guidelines and continuously learning, you can enjoy the satisfaction of working with wood for years to come. Now, go forth and conquer those logs!

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