Troubleshooting - Glow Plugs

Destroyed/lacking probe tip

Destroyed/lacking probe tip

  • Cause
    • Ignition unit failure.
    • Incorrect/irregular fuel jet direction.
    • Incorrect number or size of sealing causing incorrect spraying position.
  • Remedy
    • Check the correspondence of ignition unit with the car type and proper installation of the ignition unit.
    • Check glow plug installation hole for carbon fouling.
    • Replace your plugs.
Dimples on the probe tip

Dimples on the probe tip

  • Cause
    • Ignition unit failure.
    • Incorrect/irregular fuel jet direction.
    • Incorrect number or size of sealing causing incorrect spraying position.
  • Remedy
    • Check the correspondence of ignition unit with the car type and proper installation of the ignition unit.
    • Check glow plug installation hole for carbon fouling.
    • Replace your plugs.
Broken probe tip

Broken probe tip

  • Cause
    • Glowing time too long or voltage too high (12-V glow plug used in the 24-V system or vice versa).
    • Alternator & regulator failure.
  • Remedy
    • Check glow plug regulator (contacts).
    • Check on-board voltage and glow plug voltage.
    • Check charging system voltage.
    • Replace your plugs.
Swollen probe tip

Swollen probe tip

  • Cause
    • Excessive voltage (12-V glow plug used in the 24-V system or vice versa)
    • Alternator & regulator failure.
    • Inappropriate storage (moisture).
  • Remedy
    • Check on-board voltage and glow plug operation voltage.
    • Check charging system.
    • Check storage conditions.
    • Replace your plugs.
Bulging ring on the probe tip

Bulging ring on the probe tip

  • Cause
    • Oil in the combustion chamber (probable cause: car engine wear).
  • Remedy
    • Check piston tightness in engine cylinders.
    • Check engine oil consumption.
    • Replace your plugs.
Probe deformation

Probe deformation

  • Cause
    • Ignition unit failure.
    • Incorrect/irregular fuel jet direction.
    • Incorrect number or size of sealing causing incorrect spraying position.
    • Glowing time too long or excessive voltage (12-V glow plug used in the 24-V system or vice versa).
    • Alternator & regulator failure.
    • Injection unit operation/timing failure.
  • Remedy
    • Check the correspondence of the ignition unit with the car type and proper installation of the ignition unit.
    • Check glow plug installation hole for carbon fouling. Check glow plug regulator (contacts).
    • Check on-board voltage and glow plug voltage.
    • Check charging system voltage.
    • Check fuel injection timing.
    • Replace your plugs.
Lacking probe

Lacking probe

  • Cause
    • Ignition unit failure.
    • Incorrect/irregular fuel jet direction.
    • Incorrect number or size of sealing causing incorrect spraying position.
    • Injection unit operation/timing failure.
    • Damaged glow plug installation hole thread in the cylinder head/not tightened glow plug causing incorrect plug seating.
  • Remedy
    • Check the correspondence of the ignition unit with the car type and proper installation of the ignition unit.
    • Check the glow plug installation hole thread in the cylinder head for damage/carbon fouling.
    • Check ignition pump timing.
    • Replace your plugs.
Probe perforation, fissures or melting close to the glow plug body

Probe perforation, fissures or melting close to the glow plug body

  • Cause
    • Ignition unit failure.
    • Incorrect/irregular fuel jet direction.
    • Incorrect number or size of sealing causing incorrect spraying position.
    • Injection unit operation/timing failure.
    • Damaged glow plug installation hole thread in the cylinder head/not tightened glow plug causing incorrect plug seating.
  • Remedy
    • Check the correspondence of the ignition unit with the car type and proper installation of the ignition unit.
    • Check the glow plug installation hole thread in the cylinder head for damage/carbon fouling.
    • Check ignition pump timing.
    • Replace your plugs.
Probe in contact with the glow plug body

Probe in contact with the glow plug body

  • Cause
    • Tightening torque too high.
    • Inappropriate tool used or damage of the cylinder head hole thread.
  • Remedy
    • Check the cylinder head hole thread for damage/carbon fouling.
    • Check correct glow plug tightening
    • Replace your plugs. 
Carbon fouling between the plug body and the probe glow

Carbon fouling between the plug body and the probe glow

  • Cause
    • Ignition unit failure.
    • Incorrect/irregular fuel jet direction.
    • Incorrect number or size of sealing causing incorrect spraying position.
    • Ignition pump operation/timing failure.
  • Remedy
    • Check the correspondence of the ignition unit with the car type and proper installation of the ignition unit.
    • Check the glow plug installation hole thread in the cylinder head for carbon fouling.
    • Check ignition pump and its timing.
    • Replace your plugs.
Carbon fouling in the glow plug seat

Carbon fouling in the glow plug seat

  • Cause
    • Incorrect glow plug seating.
  • Remedy
    • Check the glow plug installation hole thread in the cylinder head for damage/ carbon fouling.
    • Check correct tightening of the glow plug.
    • Replace your plugs.
Damaged glow plug hexagon/ thread

Damaged glow plug hexagon/ thread

  • Cause
    • Tightening torque too high.
    • Inappropriate tool used or damage of the cylinder head hole thread.
  • Remedy
    • Check the glow plug installation hole thread in the cylinder head for damage/ carbon fouling.
    • Check correct tightening of the glow plug.
    • Replace your plugs.
Power supply terminal bent

Power supply terminal bent

  • Cause
    • Tightening torque too high. Inappropriate tool used or damage of the cylinder head hole thread.
  • Remedy
    • Check the glow plug installation hole thread in the cylinder head for damage/ carbon fouling.
    • Check correct tightening of the glow plug.
    • Replace your plugs.
Power supply terminal broken off

Power supply terminal broken off

  • Cause
    • Tightening torque too high.
    • Inappropriate tool used or damage of the cylinder head hole thread.
  • Remedy
    • Check the glow plug installation hole thread in the cylinder head for damage/carbon fouling.
    • Check correct tightening of the glow plug.
    • Replace your plugs.

Other damage

  • Cause
    • Ignition unit failure, incorrect/irregular fuel jet direction.
    • Incorrect number or size of sealing causing incorrect spraying position.
    • Glowing time too long.
    • Ignition pump operation/timing failure.
  • Remedy
    • Check the correspondence of the ignition unit with the car type and proper installation of the ignition unit.
    • Check the glow plug installation hole thread in the cylinder head for carbon fouling.
    • Check glow plug regulator (contacts).
    • Check the ignition pump and its timing.
    • Replace your plugs.

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