Originally Posted by 73f100shortbed
usually first thing is the thermostat, if that was replaced and done properly then unfortunately sometimes it could be a headgasket problem which can cause that.
Even if it doesn't look like a steam out the tail pipe? The coolant level is remaining up and its not missing.. The engine just got rebuilt with the heads checked out at the machine shop and new head gaskets.
Thermostat was replaced with a 195* reverse poppet stant thermostat with the spring side of it intalled INTO the intake manifold.