Expedition 4WD V8-4.6L SOHC VIN W (1999)
Spark Plug: Service and Repair
REMOVAL
1. Grasp the spark plug boot firmly and use a twisting, pulling motion to disconnect the spark plug wires from the spark plugs.
CAUTION: Spark plug wires must be connected to the correct ignition coil terminal and spark plug. Mark the spark plug wire locations.
2. Remove the spark plugs.
NOTE: Remove any foreign materials from the spark plug wells with compressed air before removing the spark plugs.
3. Inspect the spark plugs for a bridged gap.
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Check for deposit build-up closing the gap between the electrodes. Deposits are caused by oil or carbon fouling.
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Clean the spark plug.
4. Check for oil fouling.
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Check for wet, black deposits on the insulator shell bore electrodes, caused by excessive oil entering the combustion chamber through worn
rings and pistons, excessive valve-to-guide clearance or worn or loose bearings.
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Correct the oil leak concern.
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Install a new spark plug.