Vacuum Leak Serenade, Anyone?

[AlanM]

Quick poll: Has anyone experienced loud, odd noise as a symptom of a vacuum leak?

Twice, I've had engines make very loud sounds that I've tracked to vacuum problems.

The first was a Ford 6-cyl with 3-sp manual trans. Once the engine warmed, it would whistle so loudly that friends told me they could hear it over cranked-up music when the car came up their street. It was nowhere near that bad inside the car. The whistle would rise in tone and volume when the car sat at idle, like at a red light, and then drop to nearly nothing when I accelerated away, rising during each shift, and dropping when I loaded the engine in the next gear. New gaskets and proper torquing of the intake manifold connections solved it.

This week I noticed other drivers staring at our '98 V-70 NA at traffic lights, and I later realized they were looking around, trying to find the source of an annoying noise. This one sounds like someone blowing a single note through a trumpet mouthpiece. Again, it's barely audible from inside the car. And again, it fades or ceases when I load the engine by accelerating or when the AC compressor cycles on. I found that the hose that runs from the front end of the intake manifold (by the power steering reservoir) to the throttle body is leaking at the TB end. If I pinch it lightly at that connection, the sound ceases. The noise seems to be reverberating in the hose, which amplifies it.

Has anyone else heard these or other unusual, loud noise from vacuum leaks?

Al (one-note) M