i had a few posts last week on here about my cars temperature going up and down and up and down and how i put the etal head gasket in and never had the block milled but had it cleaned perfect before i put the metal head gasket on.. yes i had the head milled. I had my heater core by passed with a hose because i thought it was busted.. but i dont think it is.. i hooked it back up.. and that day it didnt over heat once . the whole day.. i take it out the next day the coolant light comes on that its low and it starts to over heat. and then drop right back down to normal after about 30-60 seconds. the coolant light came on again that it was low and the overfill tank was empty.. the thing is.. i dont know where the coolant went those times because i could smell it.. but didnt see any leak anywhere.. my oil looks perfect. i had to overfill hos epointed upward so i would see it spray on the bottom side of my hood but there was nothing.. after that happened about 2 times.. the car drove perfect the rest of the day with no temp fluctuation really.. im very very confused.. anyone have any ideas?