19.1 Engine rocker arms that do not require valve clearance adjustment are as follows (indicated by arrows) - there are no adjustment screws
1. Valve clearances must be adjusted at regular intervals when the engine is warmed up to normal operating temperature. On some models, valve clearances cannot be adjusted. These models do not have adjustment screws on the valves (19.1).
2. Remove the air filter and valve cover.
3. Set the piston of cylinder N1 to the TDC position at the time of the compression stroke. In this position, the rocker arms of the first cylinder should move freely.
19.4 When the piston of cylinder N1 is at TDC, adjust the clearances of the valves marked A - when the piston of cylinder N4 is at TDC, adjust the clearances of the valves marked B
4. In this position, the valve marked with the letter A (and injection valves located near the intake valves) can be checked and adjusted. Always check and adjust injection valve clearances first (19.4).
5. The adjusting screws for the intake and injection valves are located on the rocker arms. Loosen the intake valve adjusting screw two full turns, then loosen the locknut on the injection valve adjusting screw.
19.6 When removing the feeler gauge from the gap between the valve and the adjusting screw, a slight resistance should be felt
6. Insert a feeler gauge between the injection valve stem and the adjusting screw and carefully tighten the screw until the feeler is lightly pressed against the valve by the screw (19.6).
7. Because the injection valve spring is relatively weak, be careful not to open the valve.
19.8 To keep the adjusting screw from turning while tightening the locknut, hold it with a wrench
8. Then check and adjust the intake valve clearances, and after them the exhaust valve clearances (19.8).
9. Set the piston of the N4 cylinder to the TDC position at the time of the compression stroke and adjust the valve clearances marked with the letter B (19.4).
10. After completing the adjustment, reinstall the valve cover and air filter.