i have a 2000 honda civic ex and my engine ticks i brought it to a mechanic and he said to put new valve covers in and a new gastket and when i was tighting the last screw (i felt no resistence from the screw it wasent that tight) i turned it a little more and it littlery snapped the bottom piece where the bolt tightenns in is it bad to leave it like this and how would i fix it

 

The bolts you were tightening only requires like 20ft lbs of torque. It's not a lugnut. You will have to extract it out, the broken piece inside the threaded hole.