Noise in the engine

[excalibur1491]

Hi,

Following my "noise in the clutch" post, you probably think my car is a music box, but still, there is yet another noise...
So I brought the car to Ford for a regular service on wednesday.
I bring it back on thursday because I started hearing a noise after i picked it up.
From the inside, you can hear it commes from the passanger side, s I open the bonnet/hood and approaching my head to the space between the battery and the engine, I hear there is like an intermittent whistle.

At first, they have no idea what it is, so the ask me to leave it with them. In the afternoon, before they close I call and ask if they figured it out. They tell me "its normal operation, we ocmpared to another WQ Fiesta"... Obvisouly, when I got thee, the other Fiesta wasn there so I couldn't compare myself.
Their explanation is that there is avalve that opens and closes to release pesure...

I am pretty sure I did not hear that sound before, and it bothers me a lot because I saw the car 4 times and test drove it 4 times before buying it last thursday and now, one week later, there is a something going on already...

I recorded the sound. Its in the "Engine.doc" file (just rename it to Engine.mp3). From the begining, you hear the whistle, then at second 6, its stops and starts again. Then I moved so it makes a weird noise, but then from 10 to 13 you can hear it perfectly comming and going.

Is this normal? Or should I bring it to another mechanic? Because I can't afford going to a mechanic for nothing...
If your guess is "the steering pump", that's not it. That also makes a sound, but you can hear it comes from the steering side, not from far away, from the battery side
The exact car model: Ford Fiesta Zetec Mk6, 1.6L, engine DuraTEC

Thanks!!

By the way, its absolutely not this noise: https://www.youtube.com/watch?v=jxPVnHQia1A