---
Understanding the Lawn Mower Coil
What Is a Lawn Mower Coil?
A lawn mower coil, often called an ignition coil, is an electromagnetic device that converts the low voltage from the battery or magneto into a high-voltage spark needed to ignite the engine's fuel mixture. It acts as the bridge between the ignition system and the spark plug. When functioning correctly, the coil produces a high-voltage pulse that travels through the spark plug wire to create a spark at the spark plug tip.
The Role of the Coil in the Ignition System
The coil's primary purpose is to generate the high-voltage electrical pulse required for spark plug operation. This process involves:
- Receiving a low-voltage current from the magneto or battery.
- Inducing a magnetic field around the coil's windings.
- Rapidly collapsing this magnetic field to induce a high-voltage current.
- Sending this high-voltage current to the spark plug via the ignition wire.
This process occurs repeatedly as the engine runs, creating the consistent spark needed for combustion.
---
Types of Lawn Mower Coils
1. Standard Ignition Coil
Most lawn mowers use a standard ignition coil designed specifically for small engines. These coils are typically mounted on the engine block and are simple in construction, consisting of primary and secondary windings wrapped around a core.
2. Solid-State Ignition Coil
Modern lawn mowers may incorporate solid-state ignition coils that use electronic components instead of traditional points and condensers. These offer improved reliability, longer lifespan, and more consistent spark generation.
3. Magneto Coils
Some lawn mowers, especially push mowers, use magneto-based ignition systems, which generate the electrical current through the movement of magnets past a coil without requiring a battery. The coil in these systems is designed to work with the magnetic field produced by the magneto.
4. Electronic Ignition Coils
More advanced models may feature electronic ignition modules integrated with coils, providing precise control of spark timing and better engine performance.
---
Signs of a Faulty Lawn Mower Coil
Identifying coil problems early can save time and prevent further engine damage. Common signs include:
- Engine Won't Start: The most obvious indicator is the engine failing to start despite proper fuel and oil levels.
- Intermittent Spark: The engine starts but stalls or misfires during operation.
- Weak or No Spark: Using a spark tester reveals weak or absent spark at the spark plug.
- Engine Sputtering or Surging: Irregular engine performance may indicate coil issues.
- Engine Fails to Run Under Load: The mower struggles or stalls when under load, such as mowing thick grass.
Common Problems and Causes
Understanding typical coil issues can help diagnose and address them efficiently.
1. Overheating
Prolonged use, high ambient temperatures, or inadequate cooling can cause the coil to overheat, leading to insulation breakdown and failure.
2. Physical Damage
Cracks, corrosion, or broken wiring can impair coil performance. Physical impacts or exposure to moisture often cause damage.
3. Wear and Age
Like all components, coils degrade over time due to heat cycles, vibration, and electrical stress, eventually leading to failure.
4. Electrical Short or Open Circuit
Wiring faults, such as shorts or breaks, disrupt current flow, preventing the coil from generating the necessary spark.
5. Incorrect Coil Installation
Using an incompatible coil or improper installation can lead to poor performance or damage to the coil.
---
Replacing and Testing a Lawn Mower Coil
Tools Needed
- Spark tester
- Screwdriver or socket set
- Multimeter
- Replacement coil
Steps to Test the Coil
1. Ensure Safety: Disconnect the spark plug wire and remove the spark plug.
2. Inspect Visually: Check for cracks, corrosion, or damage.
3. Test Spark: Reconnect the spark plug wire to a spark tester and crank the engine. A strong, blue spark indicates a functioning coil.
4. Measure Resistance: Use a multimeter to check primary and secondary resistance against manufacturer specifications. Deviations suggest coil failure.
Steps to Replace the Coil
1. Disconnect Wires: Remove the spark plug wire and any electrical connectors.
2. Remove Mounting Bolts: Unscrew the coil from its mounting position.
3. Install New Coil: Position the new coil, secure it with bolts, and reconnect wires.
4. Test the Setup: Reattach the spark plug and wire, then test for spark again before attempting to start the engine.
---
Maintenance Tips for Lawn Mower Coils
Proper maintenance can extend the life of your lawn mower coil and ensure reliable engine performance.
- Regular Inspection: Check for signs of wear, cracks, or corrosion periodically.
- Keep the Engine Cool: Avoid overheating by cleaning cooling fins and ensuring proper ventilation.
- Replace Worn or Damaged Wires: Faulty wiring can cause coil malfunction.
- Use Correct Replacement Parts: Always use coils specified for your mower's model.
- Store Properly During Off-Season: Keep the mower in a dry, sheltered place to prevent moisture damage.
- Avoid Excessive Vibration: Secure the mower properly to minimize vibration-induced damage.
---
Choosing the Right Replacement Coil
When replacing a lawn mower coil, consider the following:
- Compatibility: Verify the coil matches your mower's make and model.
- Specifications: Check primary and secondary resistance values.
- Quality: Opt for OEM (Original Equipment Manufacturer) parts or reputable aftermarket brands.
- Warranty: Select products with a warranty for added peace of mind.
---
Conclusion
The lawn mower coil plays a vital role in the ignition system, directly impacting engine performance and reliability. Recognizing the signs of coil failure, understanding its types, and knowing how to test and replace it can save you time and money. Regular maintenance and using proper replacement parts are essential for keeping your lawn mower running smoothly. Whether you’re troubleshooting a no-start condition or performing routine upkeep, a good grasp of the coil’s function and issues will help ensure your mower remains in top condition, ready to tackle your yard work efficiently and effectively.
Frequently Asked Questions
What is a lawn mower coil and what does it do?
A lawn mower coil, also known as the ignition coil, converts the battery's low voltage into the high-voltage spark needed to ignite the fuel in the engine's combustion chamber, enabling the mower to start and run smoothly.
How can I tell if my lawn mower coil is faulty?
Signs of a faulty coil include difficulty starting the mower, engine misfires, weak or no spark at the spark plug, or the engine stalling unexpectedly. Conducting a spark test or using a multimeter can help diagnose coil issues.
How do I replace a lawn mower coil?
To replace a lawn mower coil, disconnect the spark plug, remove the engine cover, disconnect the old coil, and install the new one in the same position. Reassemble the cover and test the mower for proper operation.
Can a faulty lawn mower coil cause the engine to not start?
Yes, a malfunctioning or broken coil can prevent the spark plug from firing, resulting in the engine not starting or running poorly.
How often should I replace the lawn mower coil?
Typically, lawn mower coils last several years, but if you notice symptoms like difficulty starting or engine misfires, it may be time to replace the coil. Regular maintenance checks can help determine when replacement is needed.
What are common causes of coil failure in lawn mowers?
Common causes include overheating, exposure to moisture or dirt, electrical surges, or general wear and tear over time.
Can I test my lawn mower coil at home?
Yes, using a multimeter to check the coil's resistance can help determine if it’s functioning properly. However, for a thorough diagnosis, consulting a professional or following the mower's service manual is recommended.
Are aftermarket lawn mower coils reliable replacements?
Many aftermarket coils are reliable and budget-friendly options, but it's important to choose high-quality parts compatible with your mower model to ensure proper performance.
What safety precautions should I take when replacing a lawn mower coil?
Always disconnect the spark plug wire before working on the mower, work in a well-ventilated area, and wear gloves and safety glasses to prevent injury from electrical shocks or debris.
Why is my lawn mower coil overheating?
Overheating can be caused by poor ventilation, a short circuit, or a malfunctioning coil. Regular maintenance and ensuring the coil is properly installed can help prevent overheating issues.
