Field Remedy: 1826

Remedy:

Most frequent failures

Failure mode:
- thermal overload at centre-, ground electrode, insulator foot
- broken centre-, ground electrode
- insulator foot broken
- thread damaged, wrenched

Fault causes:
- tightening torque too low
- tightening torque too high

 1. Thermal overload (Picture I)

Tightening torque too low (
< 15 Nm) - spark plug was not correct tightened thereby the heat transfer was   disturbed - centre-, ground electrode and insulator foot are melted 

 2. Broken centre electrodes (Picture II)

Tightening torque too low (
< 15 Nm) - outer sealing ring thickness >
 1,4 mm
- vibration marks at the terminal head

Through vibrations the spark plug loosened and the centre electrode broke.

 3. Broken centre- and ground electrode (Picture III)

Tightening torque too low (
< 15 Nm) - thickness of outer sealing ring >
 1,4 mm

The spark plugs loosened caused by vibrations. Hence it follows breaking of
ground- and centre electrode and break out of the insulator foot.

 4. Insulator foot fracture (Picture IV)

Tightening torque too high (>
 35 Nm)
- outer sealing ring thickness 
< 1,2 mm 

Compound housing/insulator loosened

Spark plug got untight

Through shaking of the plug the spark plug has been completely destructed.

 5. Thread wrenched

Tightening torque too high (>
 50 Nm)
- strong tracks of the spark plug -wrench at the hexagon
- forced rupture in the thread

Subsequent damage (e.g. engine, cylinder) caused by described failures must not be covered by warranty.