Mystery coolant leak

[Smilieboy]

So for about the past month when I go to drive the Boss and pull out of the garage there is a decent puddle of coolant sitting where the car was. Puddle is roughly in the middle of the car where I would estimate the crank damper would be (maybe slightly to the driver side). Coolant levels look fine and are within where they've always been. No smell of burning coolant while driving. Looking under the hood I can't find any indications of leaks from any of the normal suspect locations (thermostat housing, coolant hoses, etc). Only happens when I leave it sit in the garage for long periods after driving it. When leaving work I can't find any puddles in my parking spot which is why I am getting confused. Trying to get this car back on track after a year off later this month and this isn't making me comfortable since I can't narrow this down. Best idea my mechanic could identify is it does appear like the cap on the coolant reservoir is worn out and needs to be replaced. Already have that but still had a puddle this morning before I left for work. Any ideas where I need to check or what I should just replace just in case (water pump gasket, hoses, etc)?

 

[Grant 302]

The degas bottle/filler cap is the first thing I'd suspect. Mine failed on the GT/FakeR a few years ago and I keep spares now for track days.

The other thing I would check are the coolant lines to oil cooler, if you have one. They have been known to crack and leak from the aluminum hard lines coming out of the cooler stacked plate 'block'.