I have been driving my car this winter and when the heat if left on when i turn the car off the next morning when i wake up and start it, the engine or something starts making this loud noise then after like 10 to 20 seconds it stops, anyone know what it could be? and also it leaks antifreeze when the heat is used. It comes from the freeze plug and i have to change the freeze plug about 2 times a winter to get it to stop leaking, what could be wrong with that also?