Worn, damaged or stuck valve, carbon on the valve stem or valve seat.

1. Inspect the valves.
2. Inspect the valve guides.
3. Repair or replace damaged components as required.

Worn, damaged or dirty valve lifter.

1. Inspect the valve lifters.
2. Inspect the camshaft.
3. Repair or replace damaged components as required.

Worn or damaged camshaft lobe.

1. Inspect the camshaft.
2. Inspect the valve lifters.
3. Repair or replace damaged components as required.

Worn, damaged or loose timing belt and sprockets.

1. Inspect the timing belt and sprockets.
2. Repair or replace damaged components as required.