How difficult is it to mechanically 'hurt' a hydraulic lifter? Would cranking it over with stuck valves from sitting up physically hurt a lifter- like collapse it or overstress it, or make it stick? I cranked my engine with a few sticky valves and came up with some extra valve lash- enough to make a bunch of tapping and racket and make me shut it down. I thought my cam was toast, but I can look through the drainback holes in the heads and fish the lifters out with a magnet and the cam lobes I can see and the bottom of the lifters look great. It's a Comp Cams 280AH hydraulic flat tappet with Comp Cams Pro Magnum CC-858 lifters. I used the K-Kit with all matched components and I have 7/16" pushrods, and Comp Pro Magnum 1.7 full roller rockers. After all this, I very carefully reset the lifter preload to zero + 1/8 turn per Comp's instructions and I am getting valvetrain noise like it never had before- so much I'm scared to run it. I did a leakdown and the worst cylinder was 8%- I have removed the springs and seals and used penetrating oil to work the valves loose and verified that the valves are not sticking any more. All the pushrods are still straight and my valvetrain geometry is pretty decent. Based on the leakdown, I don't think any valves are bent. I changed the oil when I started messing with a it a few months ago- I know I ought to pull it all down and go through it- just don't have the money right now. Any suggestions of stuff to check/do before pulling it down and replacing cam/lifters and properly checking guide clearance?