When the excavator repairs the valve adjustment, the machine should be parked on a level ground and the working device should be lowered to the ground.
Under the condition that the engine coolant temperature is normal, measure the valve clearance.
① Open the engine hood and remove the belt guard plate from the top of the air conditioner compressor.
② As shown in Figure 2-7, remove the cylinder head cover. Since the breather connector on the rear side of the cylinder head cover is connected to the flywheel housing through the O-ring, the breather connector and the cylinder head cover must be unplugged together.
③ As shown in Figure 2-8, remove the bolt from the top of the starter motor and insert the gear.
④ Use gear B1 to rotate the crankshaft forward, as shown in Figure 2-9, and fix the wide opening of the rotation sensor ring on the top of the protrusion of the front cover. When viewed from the side of the air conditioner compressor, the protruding yellow marks on the top and the wide mouth clamp them together. When setting the crankshaft according to the above steps, be sure to note that the pistons in cylinders 1 and 6 are not set at compression top dead center (TDC).
Figure 2-7 Remove the cylinder head
1 a bolt; 2-gear
Figure 2-8 Remove the bolt from the top of the starter motor
1—wide mouth; 2—top
Figure 2-9 Fix the wide opening of the rotating sensor ring on the top of the protrusion of the front cover
⑥ When adjusting the valve clearance, the engine should be placed at the top dead center position of cylinder 1 (during compression stroke), and 2, 3, 7, 8, 10, and 11 valves should be adjustable. After adjustment, rotate the crankshaft one turn to adjust the remaining 1, 4, 5, 6, 9, and 12 valves.
⑦ Adjust the valve clearance according to the following steps.
(a) As shown in Figure 2.10, when fixing the adjusting screw, loosen the lock nut first.
(b) Insert the thickness gauge into the gap between the rocker arm and the cross joint coupling, and adjust the valve gap with the adjusting screw. When the thickness gauge is inserted, turn the adjusting screw to the extent that the thickness gauge can be moved slightly.
1 a thickness gauge; 2 a rocker arm; 3-adjustment screw; 4 a lock nut; 5-cross joint coupling Figure 2-10 valve clearance adjustment
(c) Tighten the lock nut after fixing the adjusting screw. The tightening torque of the lock nut is (24±4) N·m. After tightening the lock nut, check the valve clearance again.
⑧ Rotate the crankshaft one turn forward, and follow step ④ to set the wide opening on the top of the protrusion to adjust the remaining valves.
⑨ After the adjustment is completed, remove the adjustment tool and reinstall the removed parts.
