Silverado Bubbling noise

My 02 silverado has started making a bubbling sound when I accelerate. The sound is coming from under the passenger side dash. Any info or suggestions would be greatly appreciated.

Check for air in the cooling system. There should be no air pockets anywhere.

mcparadise has the most probable answer. If your coolant level got low because of the chronic problem these trucks have with leaking head gaskets, and you didn’t fill the coolant reservour before air got into the system, this would have caused the problem. Did this happen to you?