I recently bought a 2007 infiniti g35s sedan with 140k miles on it about 3 weeks ago. 3 days ago i started hearing a knocking noise coming from the engine at idle and low rpms.The sound comes and goes, but doesnt seem to affect performance. The link is what it sounds like. Any suggestions?

 

Thats engine rod knock. Be prepared for some hefty repair costs. Before you do that take it to a mechanic first.

 

Turns out it was just a bad ac compressor clutch. Boy was i relieved when they informed me... easy $250 fix