Locating the spark plug on an MTD lawn mower is a common maintenance task that helps ensure reliable starting and smooth operation. This guide covers typical locations, safety steps, model variations, and practical tips to identify and inspect the spark plug on most MTD walk behind and riding mowers used in American yards.
Location Overview
The spark plug on most MTD mowers sits on the engine cylinder head, usually close to the top or side of the engine. On many models, the spark plug is threaded into the cylinder head with the ignition wire boot connected to the top. The exact position can vary by engine type, such as Briggs & Stratton or Kohler Courage series, but the basic layout remains similar: a booted spark plug protruding from the head with a spark plug wire or coil lead attached.
Safety First
Before inspecting or removing the spark plug, ensure the mower is on a flat surface, the engine is cool, and the ignition switch is off. Disconnect the spark plug wire from the boot to prevent accidental starting. If the mower has a battery, disconnect the negative terminal to avoid any electrical shorts. Wear eye protection and gloves, and never lay tools on the blade area where they could cause injury.
Tools And Materials
- Spark plug socket or a deep-well socket matching the plug size (commonly 13/16 inch or 3/4 inch)
- Ratchet or socket wrench
- Torque wrench (optional but recommended for precise tightening)
- Gapping tool or feeler gauge
- Spark plug boot puller (optional but helpful)
- Clean lint-free rag
Identify Model Variations
MTD uses multiple engine brands across its mowers, so the spark plug position may vary slightly. Typical brands include Briggs & Stratton, Kohler, and Tecumseh variants used in MTD equipment. In most Briggs & Stratton engines, the spark plug is visible on the side of the cylinder head near the air filter housing. Kohler engines may place the plug toward the front or side with a short ignition lead. Regardless of model, look for a small metal cylinder with a porcelain center and a threaded base.
Steps To Locate And Inspect The Spark Plug
- Prepare the mower by ensuring it is cool and on a stable, flat surface. Remove any grass clippings or debris around the engine area.
- Identify the ignition wire boot, which is the black or gray rubber cap connected to the spark plug. Gently twist and pull the boot away from the plug. Do not yank the wire; twist to release.
- Inspect the plug’s location by tracing the boot to the base where it threads into the cylinder head. On most models, the plug sits at a slight angle or perpendicular to the plane of the engine block.
- Remove the spark plug using the correct spark plug socket and ratchet. If the plug is difficult to turn, apply a small amount of penetrating oil and wait a minute before turning.
- Once removed, inspect the plug for signs of wear, fouling, or damage. A healthy plug typically has a light tan or gray insulator with a small amount of carbon buildup; excessive wear may indicate maintenance needs.
- Check the spark gap with a feeler gauge as required by the engine’s manual. If gap specs are not met, adjust carefully or replace the plug.
- Reinstall the plug, tightening to the manufacturer’s torque specification. Reattach the ignition boot firmly, ensuring a snug seal.
Maintenance Tips
Regular spark plug checks can prevent hard starts and rough running. Consider replacing the spark plug every season or after 100 hours of use for high-mileage American lawns. Use only the recommended plug type and heat range for the specific MTD engine model. Keep the plug clean and dry, and avoid using excessive lubrication on the threads when reinstalling. If fuel issues persist after spark plug maintenance, inspect the air filter, carburetor, and fuel lines for clogs or leaks.
Common Troubleshooting Scenarios
- Hard starting or no start: Check the spark plug for fouling or wear, verify the ignition wire connection, and confirm fuel is reaching the carburetor.
- Intermittent misfire: Examine the spark plug gap, inspect the ignition coil, and inspect the kill wire for proper routing.
- Rough engine idle: Clean or replace a dirty air filter, inspect the carburetor for varnish buildup, and ensure the spark plug gap matches specifications.
Frequently Asked Questions
Q: How do I know the right spark plug for my MTD mower? A: Check the engine model number and consult the owner’s manual or the engine manufacturer’s chart for the recommended plug type, heat range, and gap. Q: Can I reuse a spark plug? A: If the plug is clean, free of damage, and within the specified gap, it may be reused once. If fouled or worn, replace it for optimal performance.
For model-specific locations and torque specs, always refer to the mower’s user manual. If the spark plug location is still unclear, consult an authorized service center or online parts database for your exact MTD mower model to avoid incorrect installation.