GUARD AS-CENTER 1026348 - Caterpillar

Removing the Spark Plug
Ignition systems can cause electrical shocks. Avoid contacting the ignition system components and wiring.Do not attempt to remove the valve covers when the engine is operating. The transformers are grounded to the valve covers. Personal injury or death may result and the ignition system will be damaged if the valve covers are removed during engine operation. The engine will not operate without the valve covers.
Illustration 1 g00925913
(1) Cover
(2) Wiring harness
(3) Transformer
(4) Seal
(5) Spark plug
(6) Valve cover
Remove cover (1).
Remove wire harness (2) from transformer (3).
Remove the two remaining bolts that secure transformer (3). Remove transformer (3) from valve cover (6).
Inspect O-ring seal (4). If the seal is hard, cracked, or melted, install a new seal.
Pressurized air can cause personal injury. When pressurized air is used for cleaning, wear a protective face shield, protective clothing, and protective shoes.
Note: Excessive buildup of oil in the spark plug well is an indication of a damaged lip seal on the transformer.
Debris may have collected in the spark plug well. Thoroughly remove any debris. Use compressed air. The maximum air pressure for cleaning purposes must be below 207 kPa (30 psi). Ensure that the area around the spark plug is clean and free of dirt and debris.
Use a 216-1685 deep well socket, an extension, and a breaker bar to loosen spark plug (5). After the spark plug has been loosened, use the socket and extension to remove the spark plug by hand. Removing the spark plug by hand will help to detect problems with the threads. After the spark plug has been removed, discard the used spark plug gasket. If the spark plug resists removal by hand, apply penetrating oil to the threads. To help the oil penetrate the threads, turn the spark plug back and forth until the spark plug is loose.If the spark plug could not be removed by hand, clean the threads with a Spark Plug Seat Cleaner. This tool scrapes debris from the seat and from the threads in the cylinder head. Be sure to clean any debris from the cylinder.
Do not use a thread tap. A thread tap will remove metal unnecessarily. The threads could be stripped and the cylinder head could be damaged.
Inspecting the Spark Plug
Illustration 2 g00935078
(7) Terminal post
(8) Insulator
(9) Shell
(10) Gasket
(11) Hole in the precombustion chamber Inspect the spark plug closely for damage. The condition of the spark plug can indicate the operating condition of the engine.Terminal post (7) must not move. If the terminal post can be moved by hand, carefully tighten the post into the threads of the insulator. If the post cannot be tightened, discard the spark plug.Insulator (8) is covered with Teflon. If the cover is cracked or loose, discard the spark plug.Faint marks may extend from shell (9) onto the insulator. The marks may be a result of a corona that forms at the top of the shell. The conductor will develop a corona when a high voltage potential ionizes the air. This corona is a normal condition and