Recently, my engine began knocking but only in drive and reverse- (or pretty much whenever it was under load).i found out the piston clearances were super bad and replaced it. i recently got a new engine in and the replacement is making the exact same noise but much quieter, ( only makes the noise in drive and reverse). I listened around and it was most audible from the very front of the oilpan near the harmonic balancer, i decided to replace the balancer and found that since it was a JDM engine, the fan mount was a different length from the usdm one and am going to replace that as well. am i missing something? i feel like a 60000 mile replacement JDM engine shouldnt be making noises like that regardless of how quiet they are. does anyone have any similar experience or ideas as to what it could possibly be? is it possible to hear harmonic balancer/ belt issues in the oilpan with a stethoscope? this is driving both me and my pockets absolutely insane.

 

how often do you change oil ?