🔍 Key Concepts

• Valve lash (valve clearance) and what happens when it is too tight vs. too loose • How improper valve seating affects compression and combustion in a diesel engine • Which condition (too much or too little lash) is more likely to cause loss of compression or valve damage

💭 Think About

• For each option, ask yourself: does this describe what actually happens with too much lash or too little lash? Any options that reverse the effect can be eliminated. • Think about which outcome would be most damaging to a diesel: noisy operation, timing shift, poor seating of valves, or loss of compression. Which of these would be the most serious for engine operation and component safety? • Consider what happens if valves cannot fully close: how does that affect combustion pressure, temperature at the valve face, and the risk of burning or warping valves?

✅ Before You Answer

• Make sure you understand that too little lash means the pushrod/rocker is almost always pressing on the valve, reducing its ability to fully close and seat. • Confirm that proper valve seating is necessary to seal the combustion chamber and also to transfer heat from the valve to the seat for cooling. • Before choosing, ask: which condition is most likely to create a dangerous loss of compression or overheating/burning of valves, rather than just noise or minor wear?