Last night it got really cold (for here anyway), just under 0* F. I had prolly 35% coolant/antifreeze and 65% water in the system, and I checked the radiator before starting the car and there was a little slush just on the cap. So I warmed it up and as I was leaving I noticed a good sized coolant puddle under the car. Did I pop a freeze plug or what? I didn't have any leaks before. Wouldn't coolant be pouring out if I popped a plug?

 

if you popped a freeze plug it may not gush out. My best thought is see where the puddle is under the car, then look on the underside for drips. Could be waterpump, could be a bad hose clamp, could be a freeze plug. Either way, make sure you dont run out of coolant.