A bad head gasket seal: Did you tap all the threads for all the head bolt holes to ensure proper torque readings? Did you torque your headbolts/studs in stages? Did you remember to put sealant on the bottom row of head bolts on each head? (These go into water jackets).
did you change the oil after pulling the intake and stuff? its possible some coolant spilled down in there
ive been having this problem for a while not just after the intake swap.
Im looking for other possible problems other than the headgaskets to check.
would it be possible for me to drain the fluid, pull 1 lower head bolt, clean it, use some rtv and torque it back down? Do that for all of them one at a time, Just to see if that helps?
where would the timing chain cover be cracked to cause a big leak?