This document provides instructions for removing and installing inlet and exhaust valve seats in a Caterpillar 325L excavator engine. It outlines the required tools and gives a step-by-step process that includes using a valve seat extractor tool to remove the valve seat inserts from the cylinder head. New valve seat inserts are then installed using the appropriate tool and following the specified procedure. Safety notices are included to keep parts clean and contain fluids when working on the engine components.