1. Check the valve plate (Figure 2.22). The contact surface of the valve seat should be in the middle of the valve plate and spread evenly over the entire surface.
Figure 2.22. Checking the valve plate
2. If the valve plate height is less than the permissible value, replace the valve.
Normal value: inlet valve - 1.0 mm, outlet valve - 1.5 mm.
Limit value: inlet valve - 0.5 mm, outlet valve - 1.0 mm.