Low oil pressure

Insufficient or poor oil supply to valve train.

1. Perform oil pressure test.
2. Repair or replace all damaged components.

Improper lubrication to the valve rocker arms

1. Inspect valve rocker arm, hydraulic tappet, oil pump and engine block oil galleries.
2. Repair or replace all damaged components.

Worn or damaged valve finger-follower

1. Inspect valve rocker arm, hydraulic tappet.
2. Repair or replace all damaged components.

Sticking valve

Carbon on the valve stem or valve seat may cause the valve to stick.

1. Inspect valves and valve guides.
2. Repair or replace all damaged components.

Worn or faulty camshaft lobes

1. Inspect camshaft lobes.
2. If damaged replace camshaft and all valve finger-followers.

Damaged or misaligned timing gears

1. Inspect timing gears.
2. Replace all damaged components.