my header bolt is loose and my header leaks air, i'm planning on reffin my car this week. i need to fix this, it's just a little leak but it can still affect my emissions. any idea how to fix it, i already tried tapping it, i tap it with the m8,1.25mm(same as oem 12mm bolt) and it's still lose.

 

is this a stock 2 piece header or aftermarket and is it the bolt that holds the 2 peices together or the stud in the head

 

You could drill it out and put a helicoil in it, BUT, that's only if you can fit a drill inbetween the head and the radiator support.

 

it's the bolt that goes between the header and the head. it's true i tried drillin it but can't even get it straight so i just gave it cause didn't wanna messed up my head. any other suggestions.