how do you replace valves & lifters on d16z6

Welcome to AF.

The simple answer is the cylinder head has to be removed and the valves extracted using a keeper removal tool. It is an involved process that is best done by an experienced mechanic. However, as do-it-yourself project a good service manual is required, along with an accurate torque wrench.

Often valve problems can be remedied by a cylinder head rebuild. Often, the valves do not need to be replaced; instead the valves and seats are machined. Then the existing valves are reinstalled or replaced as needed along with new valve guides.

Since a cylinder head rebuild requires expensive machine shop tools, I have removed cylinder heads myself then sent them to an engine rebuild shop to be rebuilt (and to check the head out for warps and cracks), then I reinstall the head.

Is your car doing anything bad which makes you think the valve gear needs replacing?

Its probably tapping... which could be as simple as a valve lash adjustment.