B350 1 Ton Van V8-5.9L VIN Z (1992)
Spark Plug Inspection
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Preignition damage is caused by excessive combustion chamber temperature. First, the center electrode dissolves and the ground electrode
dissolves somewhat later. Insulators appear relatively deposit free.
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Determine if the spark plug has the correct heat range rating for the engine, or if ignition timing is over advanced. Also determine if other
operating conditions are causing engine overheating. The heat range rating refers to the operating temperature of a particular type spark plug.
Spark plugs are designed to operate within specific temperature ranges depending upon the thickness and length of the center electrode and
porcelain insulator.
Red, Brown, Yellow or White Deposits - Fuel Additives
DESCRIPTION:
Red, brown, yellow and white colored coatings on insulator. Engine misses intermittently under sever operating conditions.
POSSIBLE CAUSE
ACTION
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By-products Of Combustion
- Clean, regap, and reinstall. Replace if heavily coated.
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Shiny Yellow Glaze
DESCRIPTION:
Shiny yellow glaze coating on the insulator.
POSSIBLE CAUSE
ACTION
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Metal By-products Of Combustion
- Avoid sudden acceleration with wide open throttle after long periods of low speed driving.
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Spark Plug Inspection
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Remove the spark plugs and examine them for burned electrodes. Also check for fouled, cracked or broken porcelain insulators. Keep plugs
arranged in the order in which they were removed from the engine. An isolated plug displaying an abnormal condition indicates that a problem
exists in the corresponding cylinder. Replace spark plugs at the intervals recommended in the Maintenance Schedules.
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Spark plugs that have low mileage may be cleaned and reused if not otherwise defective -- SEE Spark Plug Condition. After cleaning, file the
center electrode flat with a small point file or jewelers file. Adjust the gap between the electrodes to the specified dimension. The spark plug gap is
0.89 mm (0.035 in).
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Always tighten spark plugs to the specified torque. Over tightening can cause distortion resulting in a change in the spark plug gap.
Wet Oily Deposits
DESCRIPTION:
Wet oily deposits with very little electrode wear.
POSSIBLE CAUSE
ACTION
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