If you haven't already been told, your head gaskets are blown. We just experienced the same problem. The car would run hot. The coolant levels were fine and the next thing you know the coolant was gone. Ours got to the point where it busted the radiator and cracked the coolant overflow bottle. After taking it to the dealership a couple of times, we found a service tech with half a brain. Fortunately, we caught the issue 1 week before the powertrain warranty ran out. The journey has a 5 year powertrain warranty from the date of first sale. Don't be duped. Unfortunately, they are refusing to cover replacing the radiator or cracked coolant overflow bottle. They said it's not covered under the warranty even if it was caused by something that is. If you're having an issue with your journey overheating, take it to the dealership immediately. Don't let them fool you in to thinking it was a fluke. They know about this issue and are trying to avoid losing money. Now we have to pay almost $1,000 to replace the radiator and coolant overflow. It sucks but it made no sense to drive a vehicle with a cracked radiator to another shop to be fixed for less while the dealer is already replacing the heads.
