I have a question, A few weeks ago I replaced the engine in my 1998 Chevrolet K2500 pickup. It has a vortec 350 and ever since the engine replacement and coolant flush there is a gurgling sound coming from the heater core when I accelerate from a stop. I am not losing any antifreeze. I have tried "burping" the system by letting it idle with radiator cap off and adding antifreeze. Even on a hill! My overflow can is full, and the radiator is full and still a gurgle when I accelerate!!! Any ideas anyone?!?! Thanks!! I am new here!

 

I had this problem with my 99 when it was still under warranty...there's an orifice or something like that, that attaches to the heater core at the heater hoses. Oddly enough, this orifice is supposed to eliminate the gurgling sound lol. The fix was to ream out the inside of the orifice IIRC. It eliminated my gurgling sound...maybe the 98's are the same way?

Sounds like you burped all the air from the system from the way you describe it...but the gurgling sound is usually related to an air pocket.