Which valve is typically the one that must be replaced during overhaul?

Which valve is typically the one that must be replaced during overhaul?

• A. Both valves
• B. Only the exhaust valve is typically considered mandatory replacement at overhaul.
• C. Only the intake valve
• D. Neither valve

Answer: (B)

Exhaust valves take the brunt of the engine’s heat and wear. Hot exhaust gases leave the combustion chamber and strike the exhaust valve face and seat at very high temperatures, which accelerates valve seat recession, burning, and overall wear. That combination makes the exhaust valve the most likely to be out of tolerance after service, so replacing it during overhaul is the common, safety-focused practice to restore reliable sealing and heat transfer. Intake valves, by contrast, run cooler because they deal with the incoming charge and cooler ambient air, so they generally wear more slowly and can often be reused if they still meet tolerances after inspection. Replacing intake valves happens if inspection reveals damage or excessive wear, but it’s not typically the mandatory replacement the way the exhaust valve is. So, the standard approach is to replace the exhaust valve during overhaul, with intake valves only swapped if they’re found to be out of spec.

Exhaust valves take the brunt of the engine’s heat and wear. Hot exhaust gases leave the combustion chamber and strike the exhaust valve face and seat at very high temperatures, which accelerates valve seat recession, burning, and overall wear. That combination makes the exhaust valve the most likely to be out of tolerance after service, so replacing it during overhaul is the common, safety-focused practice to restore reliable sealing and heat transfer.

Intake valves, by contrast, run cooler because they deal with the incoming charge and cooler ambient air, so they generally wear more slowly and can often be reused if they still meet tolerances after inspection. Replacing intake valves happens if inspection reveals damage or excessive wear, but it’s not typically the mandatory replacement the way the exhaust valve is.

So, the standard approach is to replace the exhaust valve during overhaul, with intake valves only swapped if they’re found to be out of spec.