so i noticed a small amount of smoke and the smell of burning coolant the other day when i popped the hood on my 06 gto. the smoke was coming from the rear drivers side of the engine. but here is the kicker, it only seems to leak when i run the heater. ive driven probably 100 miles and i cant seem to notice if it is leaking anymore because i have not been using the heater. any ideas on what this could be? i know that i could be a head or intake manifold, but then why would it only leak while the heater is on?:confused