Glenn,
The only hydraulic lifters I have adjusted were on a V-8. This was always done warm, with the engine running. I am not sure I would adjust a hydraulic in any other way.
Again, my limited experience has been that once a lifter is pumped up, it will stay that way for many moons...it will not collapse or leak down. Maybe a motor will slightly worn parts will leak down.
I think this is a moot point..a distraction. If you have replaced rocker arms and they are now functioning properly, the problem is solved. If you have time to spare, you can brainstorm why it happened, but sometimes the problem gets solved without knowing what caused it.
Stuart
