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Engine Management – V6 – Service Operations Page 6C1-3–52
Oil Fouled (3) Wet, oily deposits with minor electrode wear possibly due to oil leaking past worn piston rings. Breaking in a new or recently overhauled engine before the rings are fully seated may also result in this condition. Deposit Fouling A (4) Red brown, yellow and white coloured coatings on the insulator tip which are by-products of combustion. They come Deposit Fouling B (5) Deposits similar to those identified in deposit fouling A (4). These are also by-products of combustion from fuel and Deposit Fouling C (6) Most powdery deposits identified in deposit fouling A (4) have no adverse effect on the operation of the spark plug as Under certain conditions of operation however, these deposits melt and form a shiny glaze coating on the insulator. Detonation (7) Commonly referred to as engine knock or pinging, detonation causes severe shocks inside the combustion chamber Pre-ignition (8) Burnt or blistered insulator tip and badly eroded electrodes probably due to the excessive heat. This is often caused by a cooling system blockage, sticking valves, improperly installed spark plugs or plugs that are the Sustained high speed with a heavy load can produce temperatures high enough to cause pre-ignition. Heat Shock Failure (9) A rapid increase in spark plug tip temperature under severe operating conditions can cause heat shock and result in Insufficient Installation Torque (10) Poor contact between the spark plug and the cylinder head seat. The lack of proper heat transfer that results from poor seat contact causes overheating of the spark plug. In many cases, Ensure the cylinder head and spark plug threads are free of deposits, burrs and scale before installation. |