PLATE 9V4568 - Caterpillar

Spark Plug and Transformer
Table 1
Tools Needed Qty
9U-6695 Spark Plug Firing Indicator Gp 1
13/16 in. Spark Plug Socket 1
Illustration 1 g00737427
(1) Transformer
(2) Wire assembly
(3) Rubber boot
(4) Seal
(5) Spark plug An externally mounted transformer (1) has a secondary high voltage wire (2) between the transformer and spark plug (5).For information on checking the transformer, refer to the engine's Specifications.To prevent dirt or other foreign material from entering the bore for the spark plug, rubber boot (3) and seal (4) must be installed on the valve cover.
Both the high voltage wire (2) and seal (4) must be installed on all cylinders when running the engine. Failure to do this may allow a spark from the exposed lead to ignite crankcase vapors. Engine damage could result.
The condition of the spark plug and the changes in engine load will vary the voltage that is needed to create a spark. A new spark plug in an engine at low idle requires approximately 3,000 to 6,000 volts. At full load, 8,000 to 10,000 volts are required. If the spark plug gap needs adjustment, more than 10,000 volts are required. If the spark plug gap is not adjusted, the requirement for voltage will increase. When the voltage for the spark plug is greater than 10,000 volts, the engine will run rough.The 9U-6695 Spark Plug Firing Indicator Gp is an aid for determining ignition problems. Refer to the instructions that are included with the tool.Maintain the spark plug according to the engine's Operation and Maintenance Manual.Spark Plug Adapter
Illustration 2 g00942791If you install adapter (1) into cylinder head (3), apply liquid soap to O-ring seal (2) and the bore for the seal in the cylinder head. Apply 5P-3931 Anti-Seize Compound on the threads of the adapter and on the threads in the cylinder head. Always install a new gasket (4). Tighten the adapter according to the engine's Specifications.