Lash cap issue ???

Lash caps can be beat up if the end of the valve stem is worn so the lash cap moves side to side or rocks. It can get beat up if the valve geometry is wrong so the rocker tip stays on one side of the lash cap during the entire valve cycle or it can get beat up if the roller on the lifter is bad or it can get beat up if the spring pressure is too low so the valve is bouncing. If the lash cap is getting beat up then you stand a good chance the lock nut on the adjuster will vibrate loose and the pushrod come out or be damaged. If that happens to be an intake valve then you will get more boost on the remaining cylinders and can go into detonation. I have just been through all those problems on a motor