My explorer is pushing the coolant out of the radiator when it is warm and not pulling it back in, just curious what would cause that? Possibly a bad radiator cap? Thanks!

There might be a problem with a stuck thermostat. Check that first by removing thermostat. Running without it in winter though might be a problem... unless you live in So. Cali.

peace,

My guess is also the thermostat. If you are going to go through the trouble of checking yours, you might as well throw a new one on there while things are apart.

Also, check for a leak in the hose going to the overflow bottle (or a leak in the system). The coolent should be sucked back in by the lower pressure in the cooling system once everything has cooled back down. If you have a leak somewhere, the neg pressure (vacuum) will be lost before the coolent gets sucked back into the radiator.