ENGINE AR 1038795 - Caterpillar

Compression
Engine compression problems can result in a variation of exhaust port head temperatures between cylinders. The panel for the Engine Supervisory System can be used to determine exhaust port temperatures. By performing a compression check, the condition of the following components can be tested:valves, valve seats, pistons, piston rings, and cylinder liners. If the exhaust port temperature from an individual cylinder varies by more than 40°C (104°F) from the average exhaust port temperature, then a compression check on the cylinder should be performed. Refer to Special Instruction, GMG00694 for instructions for the test procedure.Ignition Group
Table 5
Tools Needed     Quantity    
4C-4601 Spark Plug Socket     1    
9U-7330 Multimeter     1    Spark Plugs
Voltage to cause the spark will change with the condition of the spark plug and the engine load. A new spark plug in an engine at low idle can require 3,000 to 6,000 volts to create an arc across the plug gap. At full load, this voltage will increase to 10,000 to 18,000 volts. As the spark plug wears, the gap will increase. Worn spark plugs can require over 30,000 volts to create an arc across the gap. Spark plugs will start to cause the engine to run rough (fire erratically) when the spark plug voltage requirements exceed 35,000 volts.Poor maintenance of the spark plug can add a substantial cost to an operation over the service life of the engine. The following are some ways to improve the service life and the operating efficiency of the spark plugs that are being used on G3600 Engines.
Use only the correct type of spark plugs.
The spark plugs that are used in G3600 Engines are a single strap design with an adjustable gap. The gap on spark plugs should be set at 0.29 0.04 mm (.011 .002 inch) .
Always replace the spark plug gasket when a spark plug is removed and reinstalled.
Spark plug resistance level measured between the center electrode and the extender connection point (top of spark plug) should be 6000 to 15000 ohms.
Tighten the spark plugs in the cylinder head to a torque of 68 4 N m (50 3 lb ft). DO NOT OVERTIGHTEN the spark plugs.
The correct type of spark plugs have a precious metal coating. DO NOT use a wire brush to clean the tip of the spark plug.
Do not use anti-seize compounds or allow oil or grease to remain on the threads of spark plugs during installation. Material that is placed or left on the spark plug threads and seat area will insulate the spark plug. This will prevent the transfer of heat to the cylinder head. If heat that is acquired by the spark plug cannot be transferred to the cylinder head, the spark plugs can be damaged by overheating.
The air gap between the center electrode and the strap of the spark plug provides a resistance to the flow of electricity. That resistance is necessary to ensure that the correct voltage is available before the