🔍 Key Concepts

• Identify the path of valve stem blow-by in the illustration (gas leaking up along the valve stem, not past the valve face/seat). • Distinguish between problems that affect cylinder compression (piston rings, valve seating) and those that affect sealing around the valve stem/guide. • Focus on any sealing elements shown around the valve stem in the guide area, rather than at the valve seat or on the piston.

💭 Think About

• Looking at the cross‑section, through which area would combustion gas have to travel in order to be considered "valve stem blow‑by"—around the piston, past the valve seat, or up the valve guide? • Which listed component directly seals between the moving valve stem and the stationary cylinder head, and which components are related to other functions such as spring support or combustion chamber sealing? • Ask yourself: which option would specifically prevent gases from moving up the valve guide rather than out past the valve face or piston?

✅ Before You Answer

• Verify which parts in the diagram are in contact with the valve stem and guide, not the valve face or piston. • Confirm which answer choices mention a seal or ring located in the valve guide area, where stem blow‑by would occur. • Eliminate any options that primarily affect piston compression or valve seat-to-face sealing, since these are different leakage paths.