Diagnosing a no-spark condition in a Kohler engine often involves testing the ignition coil. Kohler engines, commonly found in lawnmowers, garden tractors, and other small engine applications, frequently utilize a flywheel magneto ignition system. This system generates the spark needed to ignite the air-fuel mixture, and a faulty coil is a common culprit when your engine fails to start or run properly. Testing the coil using an Ohm meter is a straightforward process that can help you pinpoint whether the coil is the source of your ignition problems. This guide will walk you through how to effectively test the coil on your Kohler engine to determine its condition.
Understanding Magneto Coil Testing
Before you begin, it’s helpful to understand what you’re testing. A magneto coil has two main windings:
- High Tension Winding (Secondary Winding): This winding is responsible for generating the high voltage needed to create a spark at the spark plug.
- Low Tension Winding (Primary Winding): This winding works in conjunction with the points (or electronic ignition module in newer engines) to induce a current in the high tension winding.
Testing both windings with an Ohm meter can reveal if there are breaks or shorts in the coil that are preventing it from functioning correctly.
Tools You Will Need
- Ohm Meter (Multimeter): Essential for measuring electrical resistance.
- Basic Hand Tools: May be needed to access the coil and points, such as screwdrivers or wrenches.
- Clean White Paper or Electrical Contact Cleaner (Optional): For cleaning points if necessary.
Testing the High Tension Winding
This test checks the secondary winding, which delivers the high voltage to the spark plug.
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Engine Ground Connection: Ensure your engine is grounded. The engine block itself serves as ground.
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Ohm Meter Setup: Set your Ohm meter to measure resistance (Ohms – Ω). You may need to select a range, typically in the thousands of Ohms (kΩ) or autoranging.
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Connect Meter Leads:
- Connect one lead of your Ohm meter to the engine block (a clean, unpainted metal surface is best).
- Connect the other Ohm meter lead to the spark plug wire (remove the spark plug boot first for a better connection).
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Read Resistance: Observe the reading on your Ohm meter. A healthy high tension winding should typically show a resistance reading within the range of 7,000 to 10,000 Ohms (7kΩ to 10kΩ). However, it’s always best to consult your Kohler engine’s service manual for the specific resistance range for your model.
