[brcidd]

It is a sealed system- (has the radiator cap on the reservoir) these can be tricky to get them full of coolant- as you have found out- it is best toi filll cold. The sound that quit when you removed the cap is the system trying to suck in or expel air through a leak location- most likely- your cracked or leaking coolant sensor connection- this whole situation may be easily fixed by sealing that leak- or by replacing the reservoir- (salvage yard would be where I'd go) - If that doesn't work then you need to know if the radiator is not plugged, that the fan comes on etc- but start with making sure it always has enough coolant in it- by fixing that leak.