replace plentum and intake gasket, also see if your transmission fluid is milky if so your hit and the coolant and trany fluid mixed in the radiator, although rare I've seen it, but if your intake is leaking it will cause coolant to enter the intake and hydro lock, but thats an easy fix pull the spark plugs after intake is complete and crank the engine a few times about 5 to 10 secs a time