I putting the head assby back on my 02 elantra and noticed that all of the lifters are the same except one. This one has a slightly recessed head and a round 1/2 " ( 12mm) detent in the center.

It's NOt from wear. It's way too symmetrical .

Anyone seen this before?

Thanks, Scott in Vermont

 

Can you post the pic of it? I can help you then.

 

It would seem that the "weird" lifter is actually the proper replacement for the original.

 

it is symmetrical, because it is wear. That's a bad lifter, and probably the cam lobe too. Replace the lifter and lash adjuster, adjusting the valve lash in the process. good luck.