Hi, I'm new to this forum and new to working on vehicles. I inherited a 96 ranger, 2.3L from my grandfather and I've slowly nursed it back to health. The latest issue is a gurgling sound coming from heater core when I turn the heat on. It blows hot air just fine and doesn't over heat or anything. I've flushed the radiator and done numerous other tune up related things. This just has me wondering what it could be and how serious? This forum has helped me many times so I ask for any help I can get! Everything seems fine other than the noise when I turn the heater on or off. Thanks for your time!!