The valve guide is a cylindrical part that grips the valve stem in the cylinder head. The valve guide is subjected to strong frictional and thermal loads during engine operation due to the rapid movement of the valve stems moving in them. In the actuators, the valve stems can move up to 7,000 up and down per minute. At the end of the valve guide on the control side is the valve stem oil seal, which serves to isolate the combustion chamber and the control from each other.