This document provides instructions for removing and installing inlet and exhaust valve seat inserts on a Caterpillar 325-A excavator. It outlines the required tools and gives a step-by-step process that includes using a valve seat extractor tool to remove the inserts from the cylinder head and replace them if needed. Precautions are listed to keep parts clean and refer to other documents for specifications on reusable components. The document is from a service repair manual for excavator and engine models.