Diesel Data: Automotive Repair

Spark Plug: Testing and Inspection


SPARK PLUGS INSPECTION

NOTICE:
- Never use a wire brush for cleaning.
- Never attempt to adjust the electrode gap on used spark plug.
- Spark plug should be replaced every 100,000 km (60,000 miles).

1. REMOVE NO.3 TIMING BELT COVERS
2. DISCONNECT HIGH-TENSION CORDS FROM SPARK PLUGS





3. INSPECT ELECTRODE
Using a megger (insulation resistance meter), measure the insulation resistance.

Correct insulation resistance: 10 M Ohms or more

If the resistance is less than specified, proceed to step 4.

HINT: If a megger is not available, the following simple method of inspection provides fairly accurate results.





Simple Method:
(a) Quickly race the engine to 4,000 rpm 5 times.
(b) Remove the spark plug. (See step 4)
(c) Visually check the spark plug.
If the electrode is dry ... Okay
If the electrode is wet ... Proceed to step 5
(d) Reinstall the spark plug. (See step 8)





4. REMOVE SPARK PLUGS
Using a 16 mm plug wrench. remove the spark plugs.





5. VISUALLY INSPECT SPARK PLUGS
Check the spark plug for thread damage and insulator damage.
If abnormal, replace the spark plug.

Recommended spark plug:
ND: PK20R11
NGK: BKR6EP-11






6. INSPECT 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:
1.1 mm (0.043 in.)


NOTICE: If adjusting the gap of a new spark plug, bend only the base of the ground electrode. Do not touch the tip. Never attempt to adjust the gap on a used plug.





7. CLEAN SPARK PLUGS
If the electrode has traces of wet carbon, allow it to dry and then clean with a spark plug cleaner.

Air pressure:
Below: 588 kPa (6 kgf/sq.cm. 85 psi)
Duration:20 seconds or less


HINT: If there are traces of oil, remove it with gasoline before using the spark plug cleaner.

8. REINSTALL SPARK PLUGS
Using a 16 mm plug wrench, install the spark plug.

Torque: 17.5 N.m (180 kgf.cm, 13 ft.lbf)

9. RECONNECT HIGH-TENSION CORDS TO SPARK PLUGS
10. REINSTALL NO.3 TIMING BELT COVERS