Noises coming from under dashboard

Check you coolant level at the radiator, may be low, if it is conduct a coolant pressure test, there is a leak in the system. The gurggle sound may be coming from your heater core which uses coolant. This can be mostly heard at first start up, or after a long cool down period. Hope this will help.

I believe your over flow bottle has the cap on it, it may take a special adapter to connect the pressure test tool. You may want to take it to a repair facility and have a coolant diag done. Tell them your symptom your haveing it may cost one hour diag time. But it is very accurate and will save you the possibility of blowing a head gasket which lead to more money. A facility like pepboys can be very helpful. Or some place you feel comfortable with.

Have it check for an air pocket there is a port to allow coolant system to be bled at usually around hose housing on top of intake manifold. Your welcome.