SPRING 2813001 - Caterpillar

If the engine is running or the key is in the ON position, the ARD plug will continue to fire. Turn the key to the OFF position before servicing the ARD plug.
Illustration 1 g02234197
120M Series 2
(1) Wiring harness
(2) Spark plug
Illustration 2 g02152545
12M Series 2, 140M Series 2, and 160M Series 2
(1) Wiring harness
(2) Spark plug
Remove wire harness (1) from spark plug (2).
Use a deep well socket and a breaker bar to loosen the spark plug. If necessary, see your Cat dealer for the part number of the socket. After the spark plug has been loosened, use the socket to remove the spark plug by hand in order to detect problems with the threads.
Do not overtighten the spark plug. The shell can be cracked and the gasket can be deformed. The metal can deform and the gasket can be damaged. The shell can be stretched. This will loosen the seal that is between the shell and the insulator, allowing combustion pressure to blow past the seal. Serious damage to the engine can occur.Use the proper torque.
Install the spark plug by hand until the spark plug contacts the ARD. Torque the spark plug to the proper specification. Refer to Specifications, "Spark Plug" for the proper torque specification.
Connect the wiring harness.