Sam Boutin (Burlington, Vermont)
An engine/revving in idle question. Car overheated, and he found antifreeze was low, with a chunk of ice in the coolant overflow container. Added antifreeze, now car revs loudly at idle, and has white smoke coming out the tailpipe. Guys say the engine froze because of lack of antifreeze. Now it's surging because engine can't get a reading from coolant temp sensor. The white smoke means he has a blown head gasket, a cracked head, a cracked block, or all three. Likely need a new (or junkyard) engine.