radiator coolant question

[moparmike98]

This may be a stupid question but I just want to make sure.
My duster has been in storage all winter and I noticed that when I took the radiator cap off there wasn't any coolant in the top, dry as can be. When I opened the petcock there was plenty in there. Did this happen because I haven't run it all winter? No leaks that I could see

 

[BillGrissom]

Should be a sealed system. The cap only opens if >13 psig or a vacuum, the later to suck fluid back from the overflow bottle (did that level change?). You probably have either a bad radiator cap or a very small leak. Could be in the heater core, which would drain thru the firewall. Probably small enough that it evaporates before it drips. Of course, if the volume of the system changed, you might not have lost anything. Perhaps that can happen with temperature (hoses swell, etc). You can find leaks by pressurizing with air (~10 psig, lock off, see if it holds).