RAM 1500 Van V6-239 3.9L Magnum (1995)
Normal Operation And Carbon Fouling
The few deposits present on the spark plug will probably be light tan or slightly gray in color. This is evident with most grades of commercial gasoline.
There will not be evidence of electrode burning. Gap growth will not average more than approximately 0.025 mm (.001 in) per 1600 km (1000 miles) of
operation. Spark plugs that have normal wear can usually be cleaned, have the electrodes filed, have the gap set and then be installed.
Some fuel refiners in several areas of the United States have introduced a manganese additive (MMT) for unleaded fuel. During combustion, fuel with
MMT causes the entire tip of the spark plug to be coated with a rust colored deposit. This rust color can be misdiagnosed as being caused by coolant in
the combustion chamber. Spark plug performance is not affected by MMT deposits.
Oil or Ash Encrusted
Oil Or Ash Encrusted
If one or more spark plugs are oil or oil ash encrusted, evaluate engine condition for the cause of oil entry into that particular combustion chamber.
Preignition Damage
Preignition Damage
Preignition damage is usually caused by excessive combustion chamber temperature. The center electrode dissolves first and the ground electrode
dissolves somewhat latter. Insulators appear relatively deposit free. Determine if the spark plug has the correct heat range rating for the engine.
Determine if ignition timing is over advanced, or if other operating conditions are causing engine overheating. (The heat range rating refers to the
