Adjustment of CAT 374D Excavator Engine Fuel System Injector

Injector mechanism

(1) Rocker arm

(2) Adjusting screw

(3) Locknut

(4) 9U-7227 injector height gauge

To adjust the unit injectors on cylinders 3, 5 and 6, use the following steps:

1. Place the No. 1 piston at the top dead center of the compression stroke. Refer to the test and adjustment, "find the top dead center of No. 1 piston".
2. Use the injector height gauge (4) to obtain a size of 78.0 ± 0.2 mm (3.07 ± 0.01 inch). This dimension is the distance measured from the top of the unit injector to the flange of the injector body.
a. Place the injector height tool body on top of the injector tappet body. The lever of the height adjustment tool should be located on the machined flange of the injector body.
3. Turn the unit injector adjustment screw (2) clockwise until the correct height is obtained.
Note: There are two steps at the top of the injector height tool rod. The middle of the step should be flush with the height of the injector.
4. Fix the adjusting screw in this position and tighten the locknut (3) to a torque of 100 ± 10 N·m (74 ± 7 lb-ft).
5. To adjust the unit injectors on cylinders 1, 2, and 4, remove the timing bolts. Turn the flywheel 360 degrees in the direction of engine rotation. When looking at the engine from the flywheel end, the direction of engine rotation is counterclockwise. This will place the No. 1 piston at the top dead center of the exhaust stroke.
6. Repeat steps 3 to 4.
7. After the adjustment of all unit, injectors is completed, remove the timing belt from the flywheel. Reinstall the valve mechanism cover.

MEUI C injector adjustment

1. Set the engine to the top dead center (TDC) of the No. 1 piston. Refer to the test and adjustment, "find the top dead center of No. 1 piston".
2. Use the following steps to set up injectors 3, 5, and 6.
a. Turn the adjustment screw of the injector rocker mechanism clockwise until it touches the top of the injector.
b. Turn the adjustment screw 180 degrees clockwise.
c. Fix the adjusting screw and tighten the nut to a torque of 55 ± 10 N·m (41 ± 7 lb-ft).
3. To adjust the No. 1, 2, and 4 injectors, turn the engine 360 degrees and fix the flywheel with pins.
a. Turn the adjustment screw of the injector rocker mechanism clockwise until it touches the top of the injector.
b. Turn the adjustment screw 180 degrees clockwise.
c. Fix the adjusting screw and tighten the nut to a torque of 55 ± 10 N·m (41 ± 7 lb-ft).