Saab Forums - Saab Enthusiast Forum - whistling sound from the engine bay??

Hi everyone,

Would anyone have an opinion on the following. I have a 2003 SAAB 2.3, 125,000 KM

I heard a high pitched whistling sound coming from the engine bay. Upon closer inspection is sounded like it was coming from the area of the serpentine belt. About 4,000 Km the serpentine belt and idler pulley were replaced as a planned maintenance. Auto transmission fluid replaced at 100,000 KM

There are no oil leaks, no grinding sounds from the transmission, no slipping of gears and no problems with changing of gears. Forwards and reverse driving is ok.

This is what I have noticed. These observations are with the air con turned OFF

when the car is started COLD, there is no noise. After about 5 to 10 minutes the noise comes then goes, then comes then goes but never goes away. The noise is not a metallic sound like a faulty metal bearing, to me it sounds like the sound of a squealing belt rather than metal grinding on metal
if you turn the steering wheel full left to full right the sound is still the same and there does not seem to be a relationship between turning the steering wheel and the noise
all oil levels are where they should be, ie engine, auto transmission, power steering and break. All levels have always been at full levels
If you increase the engine revs, the noise does not increase or change in pitch. The noise is always at the same pitch and volume
there is a slight increase in the vibration of the car engine area since the noise has started. Prior to the noise happening, the engine ran smoother, now it is running slightly rougher, but only slightly, only so slightly rougher

Today I noticed something different. After I drove home from the city, I noticed that the noise went away when the car was in neutral or park. The noise would come back when in drive (D) or in reverse (R) when the car was stationary. I was able to repeat that many times. The noise is not continuous and comes and goes. The noise is not getting worse, ie louder.

I have driven about 30 Km since I heard the noise.

Any opinions would be appreciated.

Regards John