How long does the engine need to sit before the lifters start to clatter on startup? A good hydraulic lifter should stay pumped up for a week or so without having to refill itself on the first start. Every time the engine stops, at least a few of the valves will be open, with valve spring pressure exerted on the lifter. It will slowly leak down- - - -nothing wrong with that, because otherwise the lifter could top out and hold the valve open the next time the engine starts. The problems start when the collapsed lifter takes a few seconds to refill. Other than being annoying, the noise isn't serious- - - - -UNLESS it goes on for a minute or so. A few clicks on a cold start after sitting idle for a day or more don't cause a problem. If it's taking several minutes to quiet down, you've got problems with either the check valves in the lifters, or very low oil pressure.
Jerry
