With heavy duty industrial engines, the engine’s owner or repair shop is often faced with the critical decisions to reuse, rebuild or replace cylinder heads and cylinder head components. The individual components in the cylinder head are not to be overlooked. Beyond the machine work that may be required to bring the cylinder head casting back into reusable condition, several of the other components in the cylinder head may also be reusable. If you intend to reuse them, understanding the technical requirements of these components is necessary for qualifying them. Many of the OEMs publish “reusability guides” to help determine if these parts can be reused. However, “can be” and “should be” are two different arguments when discussing repairs. Some OEM guidelines are detailed explaining visible and dimensional things to look for, or check. Other guidelines are so vague that they leave many questions unanswered. Knowing the engine’s history, and what the future plans are for the engine are also factors in making these decisions. If you are planning to rebuild the engine and get a full second service life from it, then the cost savings of reusing the valvetrain components may not be so appealing.