🔍 Key Concepts

• Valve lash (tappet clearance) and why it changes during warm-up • How different lash adjuster types keep a nearly constant clearance as parts expand • Which systems commonly use self-adjusting mechanisms to maintain zero or near-zero lash

💭 Think About

• Think about what physically happens to an exhaust valve stem as the engine warms up—does it get longer or shorter, and what does that do to lash? • Which type of adjuster is designed to automatically take up clearance changes without manual readjustment? • Of the four choices, which one is most commonly associated with automatic compensation for thermal expansion in engine valve trains?

✅ Before You Answer

• Be clear on the definition of mechanical (solid) lash adjustment versus an automatically adjusting type • Ask yourself which option is realistically used in engine valve trains—which of these are actually found on common diesel engines? • Confirm which system can continuously adjust clearance while the engine is running and warming up, not just during shutdown or maintenance