Other information:
Inspection
NOTE:
Dropped spark plugs should always be discarded.
Unfired
An unfired spark plug should appear very clean
with a pure nickel finish to the threads and ground strap. The center
electrode ceramic insulator surface is often a matte or dull finish and
pure white in color...
WARNING:
Always allow the engine to cool before opening the cooling
system. Do not unscrew the coolant pressure relief cap when the engine
is operating or the cooling system is hot. The cooling system is under
pressure; steam and hot liquid can come out forcefully when the cap is
loosened slightly...