Cylinder Block

Cylinder Block Core Plug Replacement





Special Tool(s)





1. Use a slide hammer or tools suitable to remove the cylinder block core plug.
2. Inspect the cylinder block plug bore for any damage that would interfere with the correct sealing of the plug. If the cylinder block plug bore is damaged, bore for the next oversize plug.

3. NOTE: Oversize plugs are identified by the OS stamped in the flat located on the cup side of the plug.

Coat the cylinder block core plug and bore lightly with Threadlock 262 and install the cylinder block core plug.

Cup - Type





1. CAUTION: Use care during this procedure so as not to disturb or distort the cup sealing surface. When installed, the flanged edge must be below the chamfered edge of the bore to effectively seal the bore.

Use a tool suitable to seat the cup-type cylinder block core plug.

Expansion - Type





1. CAUTION: Do not contact the crown when installing an expansion-type cylinder block core plug. This could expand the plug before seating and result in leakage.

Use tool suitable to seat the expansion-type cylinder block core plug.

Spark Plug Hole Thread Repair
1. There is no authorized repair for spark plug hole threads. If the threads are damaged, install a new cylinder head.

Spark Plug - Inspection





1. Inspect the spark plug for a bridged gap.
^ Check for deposit build-up closing the gap between the electrodes. Deposits are caused by oil or carbon fouling.
^ Clean the spark plug.





2. Check for oil fouling.
^ 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.
^ Correct the oil leak concern.
^ Install a new spark plug.





3. Inspect for carbon fouling. Look for black, dry, fluffy carbon deposits on the insulator tips, exposed shell surfaces and electrodes, caused by a spark plug with an incorrect heat range, dirty air cleaner, too rich a fuel mixture or excessive idling.
^ Clean the spark plug.





4. Inspect for normal burning.
^ Check for light tan or gray deposits on the firing tip.





5. Inspect for pre-ignition, identified by melted electrodes and a possibly damaged insulator. Metallic deposits on the insulator indicate engine damage. This may be caused by incorrect ignition timing, wrong type of fuel or the unauthorized installation of a heli-coil insert in place of the spark plug threads.
^ Install a new spark plug.





6. Inspect for overheating, identified by a white or light gray spots and with bluish-burnt appearance of electrodes. This is caused by engine overheating, wrong type of fuel, loose spark plugs, spark plugs with an incorrect heat range, low fuel pump pressure or incorrect ignition timing.
^ Install a new spark plug.





7. Inspect for fused deposits, identified by melted or spotty deposits resembling bubbles or blisters. These are caused by sudden acceleration.
^ Clean the spark plug.