How do hydraulic flat tappet lifters fail?

you may have a valve guide issue causing all this.
I hope not, but best believe I'll be inspecting all of the guides, bores, rockers.....EVERYTHING.
Its been said that you should watch the lifters to see if they rotate on engine break in.
Stupid question, but how do you watch the lifters during break in? I suppose I could leave the valve covers off, but at 2000-3000 RPM I would guess there'd be oil going everywhere. Or do you mean turning the engine over by hand and watching them before the initial start up? That technique was mentioned earlier and I like it, going to give that a shot.

There have been so many good tips in this thread, thanks everyone.:thumbsup: