Gurgling Sound, Gurgling Sound coming from under my hood. Options

[5150EVH]

I recently noticed that when I come to a stop, I hear a gurgling sound coming from behind my firewall. I only hear this sound hear and there. I noticed too that when I turn my heat on the sound goes away....however, I smell a whiff of antifreeze when I first turn on the heat. I have been in the automotive business for 4 years (manager at Autozone and with CarQuest) and know that usually when there is overheating or this type of symptom and you turn your heater on and the problem goes away...its usually the thermostat. I was just wondering if anyone else has had this problem or if anyone could please give me some advice. I would greatly appreciate it. Thank you.

[robdrummer]

this is weird, i started noticing that in my black celica a few months ago. The coolant is fine and i see no other problems. the only possibility is that the rain catch from the windshild is blocked there fore there is rain water stuck in the firewall?

thats my guess