Is your trusty lawn mower refusing to kick into gear? That frustrating silence when you expect a powerful roar can be a real headache, especially when the grass is getting long. Often, the culprit behind a mower that won’t start is a faulty starter motor.
Don’t let a dead starter motor keep you from a perfectly manicured lawn! Testing it yourself is a surprisingly manageable task that can save you time and money on professional repairs.
In this guide, we’ll walk you through the process of how to test a lawn mower starter motor, breaking it down into simple, actionable steps. You’ll learn to identify the common signs of a bad starter and perform basic tests to confirm your suspicions.
Diagnosing a Problematic Lawn Mower Starter Motor
The starter motor is the unsung hero of your lawn mower’s ignition system. Its job is simple yet crucial: to engage the engine’s flywheel and provide the initial rotational force needed to get the engine running. When it fails, you’re left with a silent, stationary machine. Before diving into testing, let’s identify the common symptoms that point towards a starter motor issue.
Common Symptoms of a Failing Starter Motor
- Clicking Sound: This is perhaps the most common symptom. When you turn the key or push the start button, you hear a single, sharp click, but the engine doesn’t crank. This often indicates that the starter solenoid is engaging, but the starter motor itself isn’t spinning.
- Grinding Noise: A metallic grinding sound during attempted startup suggests that the starter gear might not be meshing properly with the flywheel, or that the starter motor is damaged internally.
- No Sound or Action: In some cases, a completely dead starter motor will produce no sound or any visible action when you try to start the mower. This could mean a lack of power to the motor, a blown fuse, or a completely failed motor.
- Slow Cranking: If the engine cranks very slowly, it might be a sign that the starter motor is weak or that the battery is low (though a weak battery is a separate issue to rule out).
- Smell of Burning: A distinct burning smell, particularly after attempting to start the mower, can indicate that the starter motor has overheated and is likely damaged.
Understanding the Starter System Components
To effectively test the starter motor, it’s helpful to understand its supporting cast. The starter system typically involves a few key components:
- Starter Motor: This is the electric motor that spins the engine’s flywheel.
- Starter Solenoid: This is an electromagnetic switch that acts as a relay. When you try to start the mower, it receives a low-current signal from the ignition switch and uses it to close a high-current circuit from the battery to the starter motor. It also often pushes the starter gear (Bendix drive) into engagement with the flywheel.
- Battery: The power source for the entire system. A weak or dead battery is a very common cause of starting problems and should always be checked first.
- Ignition Switch/Start Button: The control that initiates the starting sequence.
- Wiring and Connections: The cables and connectors that carry electrical current between these components. Loose, corroded, or damaged wiring can prevent the starter motor from receiving power.
Essential Tools for Testing Your Lawn Mower Starter Motor
Before you begin, gather the necessary tools. Having them ready will make the testing process smoother and more efficient. (See Also: How to Sharpen Blade on Lawn Mower: Sharpen Your Lawn…)
- Safety Glasses: Always wear safety glasses to protect your eyes from debris and potential electrical sparks.
- Work Gloves: To protect your hands.
- Multimeter: This is your most important diagnostic tool. It can measure voltage, resistance, and continuity, allowing you to check power flow and component integrity.
- Wrench Set or Socket Set: You’ll need these to remove and reattach the starter motor if necessary.
- Wire Brush and Battery Terminal Cleaner: For cleaning corroded battery terminals and electrical connections.
- Jumper Wires (Optional, with caution): Can be used for direct testing of the starter motor, but exercise extreme caution.
- Owner’s Manual: Your mower’s manual is invaluable for locating components and understanding specific wiring diagrams.
Step-by-Step Guide: How to Test a Lawn Mower Starter Motor
Now, let’s get down to business. We’ll approach this systematically, starting with the simplest checks and progressing to more involved tests.
Step 1: Safety First! Disconnect the Spark Plug
This is absolutely critical. Before you touch any electrical components or attempt to remove the starter, always disconnect the spark plug wire. This prevents the engine from accidentally starting while you’re working on it, which could lead to serious injury.
- Locate the spark plug on your lawn mower’s engine.
- Grasp the spark plug wire boot (the rubber or plastic cap covering the spark plug) and pull it firmly away from the spark plug.
- Ensure the wire is completely detached and won’t accidentally make contact with the spark plug.
Step 2: Check the Battery
A weak or dead battery is the most common reason for a mower not starting, and it can mimic symptoms of a bad starter motor.
- Visual Inspection: Examine the battery terminals for corrosion (a white or bluish powdery substance). Clean them thoroughly with a wire brush and battery terminal cleaner if any is present. Ensure the connections are tight.
- Voltage Test: Set your multimeter to the DC voltage setting (usually indicated by ‘V–‘ or ‘DCV’). Connect the red probe to the positive (+) battery terminal and the black probe to the negative (-) terminal. A fully charged 12-volt battery should read around 12.6 volts or higher. If it’s significantly lower, the battery may be the issue.
- Load Test (If Possible): Some auto parts stores can perform a load test on your battery, which is a more accurate indicator of its health under stress.
Step 3: Inspect Wiring and Connections
Loose, corroded, or damaged wiring can starve the starter motor of power.
- Trace the Wires: Follow the wires from the battery to the starter solenoid and then to the starter motor.
- Check for Damage: Look for any signs of fraying, cuts, or melting in the insulation.
- Inspect Connections: Ensure all terminals are clean and tightly secured. Pay close attention to the connections at the battery, solenoid, and starter motor. Clean any corroded terminals.
Step 4: Test the Starter Solenoid
The solenoid is often the first point of failure in the starting circuit. (See Also: Beat Lawn Fungus: Your Guide on How to Treat Lawn Fungus…)
- Locate the Solenoid: It’s usually a small, rectangular or cylindrical component with multiple electrical terminals, often mounted near the starter motor or battery.
- Identify Terminals: There will typically be a large terminal connected to the battery’s positive terminal, a large terminal connected to the starter motor, and one or two smaller terminals that receive the signal from the ignition switch.
- Test for Voltage at the Solenoid: With the battery connected and the spark plug wire still off, have a helper turn the ignition key or press the start button. Use your multimeter (set to DC voltage) to check for voltage at the small signal terminal(s) of the solenoid. You should see battery voltage when the start signal is applied. If you don’t get voltage here, the problem might be with the ignition switch or wiring to the solenoid.
- Test for Continuity (Solenoid Internal Switch): With the battery disconnected, set your multimeter to the continuity setting (often indicated by a speaker symbol or ‘Ω’). Place the probes on the two large terminals of the solenoid. You should *not* get continuity (no beep or reading close to zero ohms) when the solenoid is not energized. When voltage is applied to the small signal terminal(s), you *should* get continuity between the two large terminals. If the solenoid doesn’t actuate or fails this test, it likely needs replacement.
Step 5: Test the Starter Motor Directly
This test bypasses the solenoid and ignition switch to see if the starter motor itself is functional. This requires extreme caution and ideally a helper.
- Locate Starter Motor Terminals: The starter motor will have a large terminal for power from the battery (often directly connected via a heavy cable or through the solenoid) and a smaller terminal for the activation signal from the solenoid.
- Prepare for Direct Connection: You will need to momentarily connect battery power directly to the starter motor’s activation terminal. This is where jumper wires or a sturdy screwdriver can be used, but be extremely careful.
- Method 1: Using a Screwdriver (Use with extreme caution):
- Ensure the spark plug wire is disconnected.
- Locate the large battery terminal on the starter motor.
- Locate the small activation terminal on the starter motor (this is where the wire from the solenoid connects).
- With a helper ready to observe, carefully touch one end of a metal screwdriver to the large battery terminal on the starter.
- Then, carefully touch the other end of the screwdriver to the small activation terminal.
- If the starter motor spins, it is likely functional, and the problem lies elsewhere (solenoid, wiring, or ignition switch).
- If the starter motor does not spin, it is likely faulty and needs replacement.
- WARNING: This method can create sparks and is best avoided if you are not comfortable. Ensure you are making contact quickly and precisely.
- Method 2: Using Jumper Wires (Safer with proper tools):
- Connect one jumper wire from the battery’s positive terminal to the large battery terminal on the starter motor.
- Connect a second jumper wire from the battery’s positive terminal to the small activation terminal on the starter motor.
- If the starter motor spins, it’s likely working.
- If it doesn’t spin, the starter motor itself is probably bad.
- Note: Ensure your jumper wires are rated for the amperage.
Step 6: Check for Engine Issues (if Starter Spins but Engine Doesn’t Crank)
If your starter motor spins freely when tested directly, but the engine still won’t crank, the issue might be mechanical within the engine itself. This is less common for a starter motor test but worth noting.
- Seized Engine: The engine could be seized due to lack of oil, internal damage, or other mechanical failures. This is a more serious issue.
- Flywheel Damage: The teeth on the flywheel that the starter gear engages with might be damaged or missing, preventing the starter from getting a grip.
When to Replace the Starter Motor
Based on the tests above, you can make an informed decision about replacing your starter motor.
- Direct Test Failure: If the starter motor does not spin when power is directly applied to it, it’s almost certainly faulty and needs replacement.
- Grinding Noises: Persistent grinding sounds often indicate internal damage to the starter motor or its gear.
- Burning Smell: This is a clear sign of an overheated and likely damaged motor.
- No Response After All Other Checks: If you’ve confirmed a good battery, functional solenoid, and clean wiring, and the starter motor still shows no signs of life, it’s time for a new one.
Replacing a Lawn Mower Starter Motor
Replacing a starter motor is a moderately difficult DIY task. The exact procedure varies by mower model, but generally involves:
- Disconnecting the Battery: Always ensure the battery is disconnected.
- Accessing the Starter: This may involve removing engine shrouds, mower deck components, or other parts to get to the starter motor.
- Disconnecting Wires: Carefully disconnect the wires from the old starter motor. Note their positions.
- Removing Bolts: Unbolt the old starter motor from the engine.
- Installing the New Starter: Mount the new starter motor, reconnect the wires in the correct order, and reassemble any removed parts.
- Testing: Reconnect the battery and test the starter.
Consult your owner’s manual or search for specific video tutorials for your mower model for detailed replacement instructions. (See Also: How to Sharpen a Honda Lawn Mower Blade: Get a Perfect…)
Troubleshooting Common Issues After Replacement
Even after replacing the starter motor, you might encounter issues. Here are a few common ones:
- Still No Start: Double-check all connections. Ensure the new starter is compatible with your mower. Re-test the solenoid and battery.
- Intermittent Starting: This could point to a loose connection that’s only making contact sometimes, or a new but still faulty starter.
- Strange Noises: Ensure the starter gear is properly meshing with the flywheel. Check for obstructions.
If you’ve followed these steps and are still having trouble, it might be time to consult a professional small engine mechanic.
Verdict on Testing Your Lawn Mower Starter Motor
Testing a lawn mower starter motor doesn’t have to be an intimidating task. By systematically checking your battery, wiring, solenoid, and finally the starter motor itself, you can accurately diagnose whether this crucial component is the reason your mower won’t start.
Remember to prioritize safety by always disconnecting the spark plug wire and wearing protective gear. With a multimeter and a bit of patience, you can often pinpoint the problem and get your mower back to its roaring best, saving you time and money on unnecessary repairs.
Recommended Products
