During the exhaust valve inspection you check the guides with a go-no-go gauge and the pilot has noted there has been high oil consumption, what would be the most likely finding?

During the exhaust valve inspection you check the guides with a go-no-go gauge and the pilot has noted there has been high oil consumption, what would be the most likely finding?

• A. Worn valve guide
• B. Excessive valve lash
• C. Worn valve seat
• D. Damaged rocker arm

Answer: (A)

Oil entering the combustion chamber is most often caused by oil bypassing a worn valve guide. When you use a go-no-go gauge on the exhaust valve guides, you’re checking the clearance between the valve stem and its guide. If the guide is worn beyond spec, oil can seep past the stem into the combustion chamber as the valve operates, increasing oil consumption (and potentially causing blue smoke). The gauge helps confirm whether the guide clearance is excessive, pointing to a worn valve guide as the likely cause. Excessive valve lash would mainly affect valve timing and noise rather than oil consumption. A worn valve seat would leak combustion pressure and degrade sealing, but it’s the guide wear that directly allows oil to flow into the chamber. A damaged rocker arm disrupts valve actuation but doesn’t typically create the oil ingress responsible for high burning oil.

Oil entering the combustion chamber is most often caused by oil bypassing a worn valve guide. When you use a go-no-go gauge on the exhaust valve guides, you’re checking the clearance between the valve stem and its guide. If the guide is worn beyond spec, oil can seep past the stem into the combustion chamber as the valve operates, increasing oil consumption (and potentially causing blue smoke). The gauge helps confirm whether the guide clearance is excessive, pointing to a worn valve guide as the likely cause.

Excessive valve lash would mainly affect valve timing and noise rather than oil consumption. A worn valve seat would leak combustion pressure and degrade sealing, but it’s the guide wear that directly allows oil to flow into the chamber. A damaged rocker arm disrupts valve actuation but doesn’t typically create the oil ingress responsible for high burning oil.