At a stationary Diesel engine a valve broke after 180 operating hours. The ordinary laboratory analyses in the scanning electron microscope and the optical microscope indicated on an increased bending load of the valve to be the cause for crack initiation.

It was likely that the increased bending load was caused by the fact that guidance and cylinder head seat don’t fit together. A proof for this presumption could be won by the application of the HandySCAN 3D. For this, the geometry of the cylinder head was measured.

With the scanned geometry it could be shown that the axis of the valve seat was inclined approx. 5° towards the axis of the guidance. This lead to one-sided sitting of the valve at the valve seat (see the segment marked in green on the photo at the bottom right).