SPARK PLUG DIAGNOSIS

Spark plug diagnosis
Normal Soot formation

Possible cause:

  • Wrong mixture
  • Air filter dirty
  • Cold-start device
  • Wrong spark plug heat range
Lead settlement on spark plug Oil settlement on spark plug

Possible cause:

  • Wrong fuel
  • High engine load

Possible cause:

  • Oil level too high
  • Worn-out piston ring(s)
  • Worn-out valve guide(s)
Ash settlement on spark plug Worn middle electrode

Possible cause:

  • Wrong engine oil

Possible cause:

  • Spark plug too old
  • Engine knocking
  • Settlement in combustion chamber
  • Fuel and / or oil additives
Electrode melt down Melted middle electrode

Possible cause:

  • Glow ignition
  • Wrong ignition timing
  • Settlement in combustion chamber
  • Damaged valves
  • Broken distributor
  • Wrong fuel

Possible cause:

  • Glow ignition
  • Wrong ignition timing
  • Settlement in combustion chamber
  • Damaged valves
  • Broken distributor
  The
photographs have been kindly made available by Robert Bosch GmbH