PUMP AS-FUEL PRIMING 4W0788 - Caterpillar

The use of spark plugs with precombustion chambers is restricted to generator set applications.Note: Condensation can form in spark plugs that have precombustion chambers. This can cause difficulty for cold start-ups. To avoid condensation, maintain the coolant in the cylinder block at a minimum temperature of 43 °C (110 °F) continuously.The service life of the spark plugs is affected by fouling due to deposits from the oil and by peak voltage. Maintenance of the ignition system is also affected by voltage. Higher voltage is required by higher inlet manifold air pressure, a higher compression ratio, or retardation of the timing. Higher voltage reduces the service life of components such as spark plugs, wires, and transformers.The service life of the spark plug is different for different applications. The service life of the spark plug is approximately 3000 service hours. The spark plug may be good for a considerable period beyond 3000 service hours. To help predict the spark plug's service life, use Caterpillar Electronic Technician (ET) to monitor the “Cylinder #X Transformer Secondary Output Voltage Percentage” parameter. The value of this parameter will increase as the spark plug gap wears over time. Experience at the particular site will help to determine the proper interval for replacement of the spark plugs.If a diagnostic code is generated for the ignition transformer's secondary circuit, the spark plug may need to be replaced. Misfire and a cold cylinder are other indications of a worn spark plug. Use Cat ET to monitor the exhaust port temperatures in order to locate a cold cylinder.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 g00760567
(1) Bolt
(2) Valve cover
(3) O-ring seal
Remove bolts (1). Remove valve cover (2). Inspect O-ring seal (3). If the seal appears to be worn or damaged, discard the seal and use a new seal for assembly.
Pulling on the wiring harness may break the wires. Do not pull on the wiring harness.
Illustration 2 g00760565
(4) Wiring harness
(5) Transformer
(6) Lip seal
(7) Spark plug
Disconnect wiring harness (4) from transformer (5). Be careful to completely depress the retainer clip away from the connector. Remove transformer (5).
Inspect lip seal (6). If the seal is worn or damaged, discard the seal and install a new seal.
Illustration 3 g00760568
(8) O-ring seal
Inspect O-ring seal (8). 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. If this condition is found, clean the surface of the seal groove. Replace seal (6).
Debris may have