Spark Plug: Testing and Inspection

Spark Plug Inspection




1. Inspect the electrodes and ceramic insulator for:
2. Inspect the threads tip of the spark plugs for corrosion.
If you find any corrosion in that area, the spark plugs should be replaced. You should not clean the spark plugs with a wire brush and reuse them.

Burned or worn electrodes may be caused by:
- Advanced ignition timing
- Loose spark plug
- Plug heat range too low
- Insufficient cooling

Fouled plug may be caused by:
- Retarded ignition timing
- Oil in combustion chamber
- Incorrect spark plug gap
- Plug heat range too high
- Excessive idling/low speed running
- Clogged air cleaner element
- Deteriorated ignition coil or ignition wires




2. Do not adjust the gap of platinum tip plugs; replace the spark plug if the gap is out of specification or if the center electrode is rounded.




3. Replace the plug at the specified interval, or if the center electrode is rounded as shown above.
4. Apply a small quantity of anti-seize compound to the plug threads, and screw the plugs into the cylinder head finger-tight. Then torque them to 18 N.m (1.8 kgf.m,13 lbf.ft).