Special Tool(s)

Fig 1: Identifying Special Tool For Spark Plug Thread Repair

Courtesy of FORD MOTOR CO.

CAUTION: The cylinder head must be removed from the engine before installing a tapersert. If this procedure is done with the cylinder head on the engine, the cylinder walls can be damaged by metal chips produced by the thread cutting process.

CAUTION: Do not use power or air-driven tools for installing taperserts.

NOTE: This repair is permanent and will have no effect on cylinder head or spark plug life.

Clean the spark plug seat and threads.

Fig 2: Locating Spark Plug Seat And Threads
Courtesy of FORD MOTOR CO.
Start the tap into the spark plug hole, being careful to keep it correctly aligned. As the tap begins to cut new threads, apply aluminum cutting oil.

Fig 3: Cutting Threads On Spark Plug Hole
Courtesy of FORD MOTOR CO.
Continue cutting the threads and applying oil until the stop ring bottoms against the spark plug seat.
Remove the tap and metal chips.
Coat the threads of the mandrel with putting oil.

Fig 4: Locating Threads Of Mandrel
Courtesy of FORD MOTOR CO.
Thread the tapersert onto the mandrel until one thread of the mandrel extends beyond the tapersert.
Tighten the tapersert into the spark plug hole.
NOTE: A correctly installed tapersert will be either flush with or 1.0 mm (0.039 inch) below the spark plug gasket seat.

Fig 5: Tightening Tapersert Into Spark Plug Hole
Courtesy of FORD MOTOR CO.
Turn the mandrel body approximately one-Half turn counterclockwise and remove.

Fig 6: Turning And Removing Mandrel Body
Courtesy of FORD MOTOR CO.
Use the Feeler Gauge and a suitable straightedge to check for cylinder head flatness.

Fig 7: Checking Cylinder Head Flatness
Courtesy of FORD MOTOR CO.