Spark Plug: Testing and Inspection

INSPECTION

1. INSPECT SPARK PLUG

NOTE:
- Do not use a wire brush for cleaning.
- Do not attempt to adjust the electrode gap of a used spark plug.
- Spark plug should be replaced every 200,000 km (120,000 miles).

a. Check the electrode.




1. Using a mega Ohmmeter, measure the insulation resistance.

Correct insulation resistance: 10 MOhms or higher

If the resistance is less than the specified value, proceed to procedure "A.

HINT: If the mega ohmmeter is not available, do the following simple inspection instead.




b. Alternative inspection Method:
1. Quickly accelerate 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 procedure "B".
6. Reinstall the spark plug.




c. Check the spark plug for any damage on its thread and insulator (procedure "B").




If there is damage, replace the spark plug.




d. Check the spark plug electrode gap (procedure "A").

Maximum electrode gap for used spark plug: 1.3 mm (0.051 in.)

If the gap is grater than maximum, replace the spark plug.

Correct electrode gap for new spark plug: 1.1 to 11 mm (0.039 to 0.043 in.)




e. Clean the spark plugs.
If the electrode has traces of wet carbon, clean the electrode with a spark plug clean then dry it.

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 the spark plug cleaner.