Spark Plug: Testing and Inspection
SPARK PLUGNOTE:
- Never use a wire brush for cleaning.
- Never attempt to adjust the electrode gap on used spark plug.
- Spark plug should be replaced every 200,000 km (12,000 miles).
a. Check the electrode.
1. Using a ohmmeter, measure the insulation resistance.
Correct insulation resistance: 10 MOhm or more
If the resistance is less then specified, proceed to step (d).
HINT: If a ohmmeter is not available, the following simple method of 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 damage and insulator damage.
If abnormal, replace the spark plug.
d. Check the spark plug electrode gap.
Maximum electrode gap for used spark plug: 1.3 mm (0.051 in.)
If the gap is greater than maximum, replace the spark plug.
Correct electrode gap for new spark plug: 1.0 - 1.1 mm (0.039 - 0.043 in.)
e. Clean the spark plugs.
If the electrode has traces of wet carbon, allow it to dry and than 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 is with gasoline before using the spark plug cleaner.