Spark Plug: Testing and Inspection
INSPECT SPARK PLUGNOTE:
- Never use a wire brush for cleaning.
- Never attempt to adjust the electrode gap on a used spark plug.
- The spark plug should be replaced every 200,000 km (120,000 miles).
a. Check the electrode.
1. Using an ohmmeter, measure the insulation resistance. Correct insulation resistance: 10 MOhm or more
If the resistance is below the specified range, proceed to step (d).
HINT: If an ohmmeter is not available, the following simple inspection provides fairly accurate results.
b. Simple Method:
1. Quickly race the engine to 4,000 rpm 5 times.
2. Remove the spark plug.
3. Visually check the spark plug.
4. If the electrode is dry...OK.
5. If the electrode is wet...Proceed to step (C).
6. Reinstall the spark plug.
c. Check the spark plug for thread or insulator damage.
If damaged, replace the spark plug.
d. Measure the spark plug electrode gap.
Maximum electrode gap for used spark plug: 1.3 mm (0.051 in.)
If the gap is greater than the maximum, replace the spark plug.
Correct electrode gap for new spark plug:
1.0 to 1.1 mm (0.039 to 0.043 in.)
e. Clean the spark plugs.
If the electrode has traces of wet carbon, allow it to dry and then clean with a spark plug cleaner.
Air pressure: Blow 588 kPa (6 kgf/sq.cm, 85 psi)
Duration: 20 seconds or less
HINT: If there are traces of oil, remove them with gasoline before using a spark plug cleaner.