Was wondering if anyone outh there had any ideas or theories on this. So my car overheated one day a few months ago due to a small leak at the coolant elbow but the gauge didn't show it I ended up blowing a headgasket. Towed the car home and when I started it up again there was a really loud knocking sound that wasn't there before it sounded horrible it was like that for a day or two then all of a sudden it just went away so now idk whether I should just change the headgaskets fix leak and be done with it but what if I end up doing that and something else is wrong?? Any help would be appreciated

 

Oh and also my mechanic checked the oil pressure and said it was fine although he didn't know the specs but he said it was fine also the car was throwing a misfire code