What would make the rocker arm break on a Durango. If all I was getting done was

4.7 engine --- exhaust valve.... rocker just popped off and won't stay on if put back in place??... Check compression on that cylinder!..... 5.7 engine--- and rocker just really loose for no apparent reason? ..Valve spring down lower that others beside it?.. What I'm getting at is both engines have their share of valve train problems!!.. The 3.7 is included btw..

NO , the problem was there prior , just poor luck/timing on the part of the person stuck doing the oil change! --Why was it getting an oil change?? I know that sounds 'simple' , but if it was being changed BECAUSE you heard a noise , and you thought the oil change would fix it , then you got the answer , albeit , not in the way you wanted it!... What inspection was done to properly determine the cause of the failure?