The answer to 'pressure regulator making gurgling noise' is that a gurgling sound from a pressure regulator is often caused by a buildup of sediment or debris in the regulator. This can restrict water flow and cause the regulator to make a gurgling or vibrating noise.
Some common causes include mineral deposits, rust, or other debris that gets trapped in the regulator over time. This is a common issue, especially in areas with hard water. The gurgling sound is a sign that the regulator needs to be serviced or replaced to restore proper water pressure and flow.