Problem: Carbon fouling
Causes: Glow Plug is incorrectly installed and as a result the cooling capacity has been altered; the duty cycle of the vehicle is too low
Solutions: Ensure that both the tube and seat are clean when installing the glow plug
Problem: Damaged or missing probe tip
Causes: Failure of ignition unit; direction or regularity of fuel jet incorrect; sealing fault causing spraying position error
Solutions: Check the ignition unit is correctly installed; check you are using the correct ignition unit for the vehicle model; check the Glow Plug installation point for carbon deposits
Problem: Missing probe
Causes: Ignition unit failure; direction or regularity of fuel jet incorrect; wrong spraying position caused by faulty sealing; function or timing fault in injection unit; thread damage to opening of cylinder head where Glow Plug is installed; Glow Plug insufficiently tightened causing plug to sit incorrectly
Solutions: Check you are using the correct ignition unit for the vehicle model; check the ignition unit is correctly installed; check the Glow Plug installation point for carbon deposits; check timing of injection pump; check the opening of cylinder head for thread damage/carbon fouling
Probem: Swollen ring on the probe tip
Causes: Oil in the combustion chamber, probably caused by engine wear
Solutions: Check piston clearance in engine cylinders; check oil consumption
Problem: Enlarged probe tip
Causes: Excessive voltage e.g. 12-V Glow Plug in a 24-V system or vice versa; failure of alternator and regulator; dampness during storage
Solutions: Check on-board and Glow Plug voltage; check charging system; check quality of storage conditions
Problem: Deformed probe (overheating)
Causes: Failure of ignition unit; direction or regularity of fuel jet incorrect; wrong spraying position by faulty sealing; excessive glowing/voltage e.g. 24-V Glow Plug in a 12-V system or vice versa; failure of alternator and regulator; function of timing fault in injection unit
Solutions: Check the ignition unit is correctly installed; check you are using the correct ignition unit for the vehicle model; check the Glow Plug installation point for carbon deposits; check contacts on Glow Plug regulator; check on-board and Glow Plug voltage; check charging system voltage; check fuel injection timing
Problem: Bent terminal
Causes: Impact within the combustion chamber; temperature too high in combustion chamber
Solutions: Correct installation and better care when installing the Glow Plug is vital
Problem: Probe touching body of Glow Plug
Causes: Over-tightened torque; wrong tool used; thread damage to opening of cylinder head
Solutions: Check the opening of cylinder head for thread damage/carbon fouling; check Glow Plug torque
Problem: Broken probe tip
Causes: Excessive glowing/voltage e.g. 24-V Glow Plug in a 12-V system or vice versa; failure of alternator and regulator
Solutions: Check contacts on Glow Plug regulator; check on-board and Glow Plug voltage; check charging system voltage
