This is such a strange problem, there is a loud squealing sound coming from the thermostat/FPR area of my engine bay. It only makes the noise when the car is warm, and off throttle. I disconnected the serpentine belt and it still does it, and today I took apart the timing belt system and both the pulleys seem to be moving freely.

Is there anything else in that area of the engine that could make a sqealing sound? I would just try replacing the regulator, but on my car (97 850 AWD) its built into the fuel rail. Not even sure how I'm going to get a replacement.

 

Sorry, I should say fuel pressure pulse damper, there isn't a fuel pressure regulator on my car. Upon further inspection, iPd does sell this item for $50. I suppose I'll order one and hope that I'm right about the timing belt pulleys :$

 

Unless your idea of "squeal" is way different than mine I'd think it was something in the timing belt components or water pump.

 

It sounds like a bad power steering pump, except the pitch and volume don't change with engine speed.

The guy I was talking to at the wreckers today was saying water pump as well, but that's not really where the sound is coming from and I replaced the water pump with an OEM model a year ago when I did the timing belt.

 

 

Sounds like metal scraping. The video would not play, stopped every 1/2 second.

 

That is a new one on me. Very high frequency shrill whistle.

I don't think that pulsation dampener is going to be able to create that.
Doesn't sound like any water pump bearing noise I know of.
Like RSPI, it could be metal to metal but it just seems too high pitched, frequency for how fast anything is spinning at idle.

I'd take a squirt water bottle and spray around to see if you uncover a vacuum leak. Any intake connection or vacuum source could be suspect but especially head to intake.

Video played ok, stopped a time or two on me but I can hear the sound.
What does it do if you slowly accelerate and what if you blip it ??

 

"except the pitch and volume don't change with engine speed."
Sorry, didn't read close enough.

 

Yeah, don't think i've heard anything like that either. I would get the stethoscope out and pinpoint where it's coming from first..

Did you ck the fuel pressure at the rail? Might try pinching the fuel return line and see if that changes the noise.