Hi y'all. About a 3 weeks back, I noticed that my 2001 jeep Wrangler was overheating at idle. Then I check the coolant level, the reservoir is empty when the engine is cold. But I couldn't see any leaking and I replaced the radiator couple months ago. And no sign of burning coolant either. Other than that, it runs great and smooch. I can't figure it out what is happening.