BOLT 8S4740 - Caterpillar

All 3412 EnginesSeveral changes have been made to the fuel systems used on 3412 DIT and 3412 DITA Engines. The same fuel injection pump and governor group used on the DITA Engine is now also used on DIT Engines. Also, new fuel lines, fuel injection nozzles and new fuel injection nozzle adapters are used on both types of engines.
These changes are in effect with the engine serial numbers shown in the chart.
Fuel Injection Pump And Governor Group
The fuel injection pump and governor group used on 3412 DITA Engines is now also used on 3412 DIT Engines. This fuel injection pump group uses 10.0 mm fuel pumps and new nozzles, and an orifice reverse flow check valve that is compatible with the new fuel injection nozzles. The former DIT Engine used 10.5 mm fuel injection pumps with capsule-type nozzles. The DITA fuel pump has steel lifters with wider rollers to more evenly distribute the load on the fuel pump camshaft. This gives improved service life to the fuel pump camshaft and lifters.
Fuel Injection Nozzle
New fuel injection nozzles are used. The 4W7018, 4W7019 and 4W7020 Nozzle Assemblies are used in 3412 DIT and 3412 DITA Engines, and require the use of a new fuel injection nozzle adapter to hold the fuel injection nozzle in the cylinder head (see illustration). A new 7W4482 Copper Washer (gas seal) is used with the new fuel injection nozzles. The specified torque for the new adapter and retainer are shown in the chart that follows.
New 7000 Series Fuel Injection Nozzle with 40.45 mm (1.593") adapter bore.Fuel Lines Group
A new fuel lines group is used. The inside diameter of the new fuel lines is 1.83 mm (.072"). A new 5B1484 Nut goes through the valve cover.
The fuel line part numbers are shown in the chart.