[Caddy_lackin2982]

i have a 2004 caddilac cts with the 3.6L engine, i picked it up for a good price down south in texas and drove it up to mid wisconsin during the winter and it sat in my driveway for one night and the next day when i went to drive it, it overheated for a little while then the temp leveled to normal so i didnt think much further than that. then when i went to add coolant it pours the coolant right out the back side of the motor and its overheating. i was thinking either freeze plug or head gasket but not sure. what do yall think?

 

[RyanY]

Could be those, or the thermostat seal (behind the intake manifold). Only one way to find out...gotta tear it apart until you find it.

Edit: or put a leak tracer in the system and watch for the leaks.