96 Isuzu rodeo

hi i have a question and maybe somebody could help me i have a 96 isuzu rodeo ls and as everybody knows the tapping noise it was not loud but you can here it just a little bit i let my friend drive it and he told me when he was driving there was a loud pop and the noise stopped from there i would like to know if the valve lifter or rocker arm just failed on it i just hoping it wasnt the piston